WORLD HEALTH ORGANIZATION ORGANISATION MONDIALE DE LA SAUTE

REGIONAL OFFICE BUREAU REGIONAL

FOR T H E EASTERN MEDITERRANEAN POUR LA MEDITERRANEE ORIENTALE

SEMINAR ON IiEAm HAZARDS OF PESPICIDES

Cairo, 17-21 July 1972

EM/SEM. HLTH.HAZ. PE3T/14

ENGLISH ONLY

PREVENTION AND CONI'FOL OF ENVIRONMENTAL

Dr V.B. ~ o u k + WHO Headquarters

* Environmental Pollution, Division of Environmental Health, WH0,Geneva

i,?a0/?2/938

Chemistry

Amlvtical methods

Transport processes in the environment

Levels i n environmental samples :

Organochlorine insecticides

Organophosphorous insecticides

Herbicides

I4ercux-y

Disposal of pesticides and control of

environment a1 pollution

References

Xnviromental pollution by pesticides, may resu l t from t h e i r production,

transportation, use, disposal or accidental release. Occasional outbreaks

of mass poisonings, the wid.e-spread presence of pesticides in the environ-

tncntal, and the uncertainty a s t o the ecological consequences of such pollu-

t ion has led t o dras t ic leg is la t ive action in some countries, including the

prohibition of production hnd use of cer tain classes of pesticides (FJHO,

1970). Because of the i r world-dde use a d the f a c t t h a t p r s i s t e n t pesti-

cides can be t r w p c r t e d over large distances by atmospheric transport and

other ncchanisms, environmental pollution by pesticides i s considered a s a

prdcllsm of global scope. (Study of Cr i t ica l . h v i r o m n t a l Broblems, 1970).

Cherilis t r y

mere is a la rge -variety c6 compourrls used a s insecticides, fungicides,

herbicides, fumigants and rodenticides, They include inorganic compouTds

such'as copper sulphate, sodium chlorate, calcium and lead arsenates,

mercuric and mercurous chloride; c h l o r h t e d hydrocarbons l i k e DD?, aldrin,

dieldr in and heptachlorj organophosphorous cornpounds such a s parathion,

diazinon azr 'malathion; carba.nates; chlorimted p h e n q a c e t i c acids; organic

mercury compounds and others, Jm;~enclature and structure of some of these

c o m p o ~ s is sham fn the Annex.

The chenkcal, ph<pical arid toxLc properties af these conpounds can d i f f e r

widely, a& so can t h e b po tmt ia l as environv~ntal pollutants; t.he inportant

physico-chemical properties include the volat i l i ty , the solubi l i ty i n water

and organic solvents, and the resistance t o chemical and biocherdcal degra-

dation.

Chlorirated h-idrocarbons and organic mrcuqy compounds a re predenay the

two rnost important classes of pesticides in relat ion t o e n v i r o m n t a l pollu-

tion. &though there i s insuff icient information avai1a.de to &terntine the

actual production and use af these compounds, it has been estimated that the

yearly production of DDl. i s of the order of 105 metric tons (study of

Cr i t ica l ~lnviromentd":~roblems, 1970); a s repcrted by S m r t (1968) the

pes t ic ida l use of :mrcury compods in the world was not l e s s tban 2 x ld metric tons.

The various t:rpes of arganociiiorine coiiourds are i l lus t ra tsd i n Eg.l.They

,- ' CI

HHON. U ective component in aldrin) (sdi-~e component tn dieldci?)

' pc:,chlsrin:?cd 'bi3enylt rh!orinarcd rwphrha:fne: c".l=r;r.x;cd dikerzsi;s.c:-e: 1 . . (trace impurisi~s ix 2.4.5-T

and wn>e chlorophencis) ,

incl.irde insecticideis uliicit ?oay !re ~ l . ? h 5 ' i : ' j ? r ! S.n,to sxal .h~: ies .:~icl cl~J.rt~..ine;~c! . .

cycloal kanas; chlor%nated ?hennxyateti.c acids, used as heibicibes, and fu:*g~c~~!ce

such as hexachlorobenzene md yerttechiaropllen~l. Chlori~atcd ermatics ~ i l i ~ h

polyclttorinated biphenyh are used induc~rially. Generally, chlorination of a

hydrocarbon increases the resistance of the compound to both chemical end biochemical-

degradation, Iacn a molecule such as p,pLDDT also includes cl~loriaated aromatic

gkoups, its half-life time in the environment increases from inonths to years. :tho

term ,has ohen been +ised for chlorinated hydrocarbons, but it is more

appropriate to say that some of thexi are very resistant t o biodegrsdation. Rates cif

biochenicd degradation vary f o r diffetett compounds: the time ~equirild for a 50

per cent change (the half-16f e t ir.e) is of .fhe-urded-& 0.05 l o about 2 years.

l t ~ t e c of degradation ig the abiotic eofmponente-6f && cpvirawuini: (soil, water, tiil.)

may be much slower. In'cold zones, i n water pbtjF;fanutrieats, p,pLWT is stale

fox a long time; in soil, i t s residenr,e,,,haIf-li-fa nay he up to 10 years. The 3

metabolism of p,p9-CDT takes place la the aliphatic part of the molecule and

usually proceed& by either uZ tile foiiowing two g~bwayus

r , W-G.C- H 4 . 0 H-C- COO13 0, Gl dc: 1

Other metabolites of acrme organic chlorine compounds are ,shown in Fig. 2.

It is fntereeting to note tbat:.ths known metabolites o f some orgaoo-chlorine

compounds o-ften contain as ararty chloro-sutistituents as the parent compound. This

is probebly a consequence of the relative s tabi l i ty of the C-C1 band as compared

to C-R. Further, once the polar metabolites are formed, the C-G1 bond becmes

e v h more .stable than in +,ha parent compound. For exampie, DDE is more s t a b l e than

p,pt'-llbT (Rcbinsoa, 1911).

htelabclitcs o f some organucf;/orinc ooarpounds. (Robinson, 1971)

Parcnt conlpou~td Mctzboli bcs

A- >CliCt-ICI, @p'- TOE)

or> C = CC12 @p'- DUE) p,dCHCC13

. or>C=O CI .-... \i ci-

- . L-=/ 'or> CH$O&I @p'- DDA) ppe- DDT

iildrin, a s an alycyclic chlorinated hydrocarbon, i s l e s s resis tant t o

oxidation than ppv-DD, and is readily converted t o the epoxLde - dieldrin.

Further de~radat ion takes place i n the epoxide riq. to the &-alcohol, but t he

molecule m:r be altered a t other s i t e s as well. Fndrin i s a steroisamfler of

dielddn. Lindane i s a fu l ly chlorimted conqourd and may be metabolized i n

several ways, the dominant t r an s fomt ion yielding trichlorobonzene. .The

b e t a i s m r of lindane i s considerably more stable than other isomrs.

the solubil i ty i n watcr and the vapour pressure are important charactcriafics

of organo-chl.orine conpourrls (Table 1) .

TA.:LE 1

Som Praperties of Lertain Organochlorine insecticidest

Compound Solubility in

Tapour *esL3lrrc gater parts (rmn Hg) Per ~ i l l i r n

hldrin (EDN) 2.3 x lo-5, 20% 0.20

Gamma-BHC 9.4 r loA, 20°C 7 pp 1 -DDT 1.9 x 20°C 0.04 Dieldrin (KiCB)) 1.8 x 2S°C 0.25

Endrin 2 x 25'C 0.23

Iieptachlor 3 x lo4, 25'C 0.1

pp f -2DL 1 x lo4, 25.C 0.1

Camphechlor (toxaphenc ) 0.2-0.4, 2S0C 3

Generally, the solubil i ty of chlorinated hdrocarbons i n water i s low

compared t o the solubil i ty i n organic solvents including fats . They tend,

therefore, to concentrate in the a m t i c and other animls, partlcufarly j#w

f a t t y tissue. 1 % ~ al iphatic chlorinated hydrocarbons are m o r e ua- soXuEW

than the aromatic ones such a s ppf-DD$ and the concentration factors in

organisms over water are therelore lower: of tho order af 200 as compared t o

20 000 fo r DEW. It :ws also been sq;gesCed that Z I T my be concen- trjtcd i n mrgacc o i l L 2 : x loud i n nt;tur:.l r-~l.om, and thnt the

3 Source: ip,ricultural .*search Council 1970

mL*mt=/u zciicentsrition *there may

WE%. mm rcsch leve l s s ~ f f l c i m t t o c a s e aeilta toxi.city t c tilf

pkyto;:lzn!:to::. Anothcr can::cquencc of t he i r l o x s o l u b i l i t y i.n wntcr is t k z t tI:::::

~.,n_.easily abs~rbed by the parti.cirlatc matter suspended i n nn tu ra i waters acd by

t h e bottom sedihe.nts, Or: the other h a d , some metnbolires of ch10rir)ztcct hydro-

?*rbons may tend tc accunurate i n the hydrosphere as a resulr .of the i r increased

hydrophi l ic i ty and s t a b i l i t y t o chcmi.~ril nr S i u c ~ ~ ~ r a i c a l dcgradar:on.

The organc~hospt~arous insec t ic ides (see Aqnex I) can be classified i n to a l i p h a t i c

'- .?ytivtrs -(such as malathion o r mevinpI~os) and aromatic der iva t ives (such as

dlazinon;cr gpritthion). Thcy ere a l l atructtrrslly related nac! tindergo s imilar

react ions w c h as oxidation, hydro1ysi.s and denethylation.

-0 - . CQp

C H O 2 5

Parathion Uie thy1 p-Nitrophenol Thiophosphate

311 orgsnophq~phorous.insecticides are inhihij;rrrs-of the enzyme cholinesterase.,

Some 6f- t b w are e f f ec t i ve p_er-s@, others -undergo oxLdative conversion i n plants

and animals (eg. parathion-paraoxone) . ~ x ~ d a t k o n s ~ usual ly increases the water

s o l u t i l i t y and may improve the anticholiaes'terase a c t i v i t i es. Orga~ophosghorous

cmtpounds'~differ largely wi&'respect to ' t he i r v o l a t i l i t y and s o l u b i l i t y i n water.

For example, the s o l u b i l i t y bfparathj.on i n water . is about 24 ppm, of malathion . .

145 ppm and dimethoate 7000 ppm. Some of t h e water so1uli:n. compounds a r e very

unstable. Soil. microorganisms metabo1,ise the organophosphqrous compounds f a i r l y

hiso rile LigEicr thr pti, t h e faster i s ti-tn r a t e o f hydroiysis. '~'hil:: itndc.r :?iel.<i

conditi.uns it: i .s rc l l i i ce iy that uiost of these compounds will. remain for any great

length of tirue in soil o r water , but there are of course variai:ions. ParatI~ion has

be211 found i t 1 t r a c e s i n ground water, for exmiple. Most of t h e o r g a n o p h o ~ ~ p h o r o u ~

c.ampounds a r e t o x i c t o f i s h , bur do not accumulate i n animal. t issue.s.

The carbamates, l i k e organophospharous compounds, arc cho l ines te rase i n h i b i t o r s .

Generally, they zre unstable, a r e metabolised rap id ly in animals, and sl~or? little

tendency t o accumulate in animal i i ssueu. Carbaryl has R h a l f - l i f e i n soil. o f

about e igh t days, Some dithiocar:>arcatcs, such as sodiun d ine thy l ditliiocarLan.fi~e

arid disodiun~ ethylex~bbisdithiacarba~nate (Nabam) hwe-.outstanding £ungicidal properties

they are water so lub le and unstable; t h e i r nets! -cmp.lexes such as forbam, cmneh,

zi~2n, zineb and thiram are water inso lub le and,_staW.- .. . -Under acid conditi.ons they

brcak down i n t o dimcthylamine and carbon disalfi.de. AH the pii increases , t h o

s t a b i l i t y i n c r e n s e s w u b s t ~ ~ t i a l l y . Their metal ions c a ~ i he dj.sp1.aced hy cnpper

giving h igh ly sy&?e cclpper cc;;p:rizes, vhicB couie--regain ip the wivirs:aiie:;t'far e

long time.

".a A. Fungicidca i;iil:it2n ti xdo~ber o: inorganic etip.+rga~iic mercuxy cotiqjcjsilrsdo. Typi - .-'

examples are e t h y l mercuric chlor ide , Pa, pancgen and eeresan~P1.

- Ceresan M

Together with chlor inated hydrocarbons of DDT t y p e , they a r e t h e most potent

environmental poi'irrtancs.. Large q u a n t i t i e s of orgi.;:lo cici-curials arc uscd for .s'ccd

treatment. This usage enables mercury to enter a variety'of craps, meats and eggs

through. food chains i n the erivironment. Because o f its high t o x i c i t y t o man.

r;anop,eil byas banned in S.,i.eden in 1966 and i.n 1970 i t s export from Sweder vcs' ;:$?so

. In & d i . t i ~ . % tt, y ~ c 3 f ; r ~ a t m : ~ t , n3.kylmerCtli)'- ~ c ~ : ~ c v . r : ~ s 3x9 + t - n G . ..> -:.;!.-*.- c + i l

s i v e b On potato, tomato a d apple crops. T h e r e is cv5dence that: "cl,c traos1occ;tion

of mercury may occur causing accumulation in harvested crops frcm pretreated seeds

and plants.

It has recently been discovered that anaerobes in sludge from aquaries can

methylate inorganic mcrcuq~. This reaction can happcc i2 one of twu ways (Sensen

- . ' \ . and Jernel;v, 1966; Wood. 1971.:

&2+ --.-- + a? - (CN rig - ' / -.-----+ CB ~g + x CH

2Lc - CH 3 2 .. 3 . 3 3 X

'i T!xc f c m a t i ~ r , of n%mom,othylmcrcur;. f m ~ m diecthyXncrcury dc>cndz o:: t ! ~ ;\!? cf. EEC

medium; under mild acidic reaction tEe fallowing rcacticn . . occurs:

The follosing gei~eral scheme for the synthesis of methylmercury compounds irr the

enviro~~ent has been proposed (Wood, 1911).

I Chemical transfer of .cli3@

The significance of these reactions- is tha t both inorgan% and organic

mercury compounds can be transformed Ln the environment into highly toxic mdhyl

mercury. ,Since methylmercury is a non-polar compound, mcnlbtane transport can occur

easi ly and the campound is readily assimilated and concentrated in a variety of

animals including man. Alkylmercury compounds are uniformly distributed throughout

the body; significant amounts pass through the brain membranes and accu~ulite causin

disintegration of brain cells. Passage or ore~nancrctrrials across ? t a c ~ n t a and

concentration o f them kn the foetus causes a sp~ecial prabl.en! (fetotoxicity).

The chlorophenow herbicides, such as 2,4-D and 2,4,5-T, are used i n large

quantities and directly applied t o lakes, r ivers and other surface waters for weed

control. 2,4-D may persis t for several months i n lake water; its esters are

usually broken down i n a few days ( A l y and Fairst , 1964). However, the bacterial

degradation of these compounds i s generally sufficiently rapid so tha t phenoxy herbi-

cides are not l ikely t o present a major water pollution problem. !he only.herbicides

tha t may remain active in the environment fo r several seasons are those belonging t o

tb propionic acid group such as dalapon.

Analytical methods .-.-- Approximate l i m i t s of detection of pesticides by various analytical teckmiques

are shown i n Table 2 (Zweig, 1970).

Approximate . .-- - - . L i m i t . .- ---.- - of ..-. Detection ..--- - - - - -. of ." --- Pesticides -... - .. --

Method of analysis Examples of Pesticide

Colorimetry DM!, parathion lo-5 Fluommetry Guthion Infrared spectrophotometry Thiodan

Oscillography DDT

Parathion

Paper chromatrogrkphy DM'

Thin-1wer chromatography

Gas-liquid chromatography

Detector:

Kathmmeter

Electron-capture

Microcoulometry

Themionic

F3me *otal6try-P

Flame photometry-S

Chlorinated and phosphate lo-7 - 10 -5

Thiodan

:DM'

.Dm

Parathion:

Dimthoate

Gmite

EM/SEM.HLTH.HAZ.PEST/~~ page 10

I n general the quantity of pesticides found in the environment is a t most a t -6 -8

the part per million level (10 ) and very often a t the part per hundred (10 ) or thousand million level (lo-'). There are three stages i n the analysis:

1) The extraction of, the . wsLdue from the sample.

2) The clean-up of the extract from intercering substances.

3) The end-method of ident if icat ion of the residue i n the clearied-up

extract.

Extraction methods t o be used depends on the type of pesticide and the sample

being analysed. For vegetable products one can start f o r examp1e.b~ macerating the

chopped vegetable material with acetone and parti t ioning the acetone extract wigh

5% N a SO solut3.w and- n-hexane solution (Goodwin e t al., 1961). The n-hexane 2 4

solution w i l l contain over 80 per cent of the pesticide normally i n a clean enough

form t o allow paper t h i n - l a s r an5 gas-liquid chromatography t o be used directly.

A similar procedure m a y be ef f ic ient f o r organophosphorous compounds i n fresh

vegetable material. I f vegetable products are not fresh, a 3:2 mixture of ethyl

methyl ketone and hexane is used instead of acetone (Egan e t al., 1964). For gas

chromatography this extraction procehre is t o be followed up by the alumina column

clean-up.

The most important pesticides i n a n i m a l products are the chlorinated hydrocarbons.

The extraction with hexane followed by a solvent part i t ion between hexane and methyl

cyanide has been suggested as a good procedure (Jones and Riddick, 1952). For gas

chromatography it may be advantageous t o use a dimethyl fonamide part i t ion pro-

cedure i n the extraction phase o f ' t h e analysis. Detailed procedures have been worked

out for different types of samples, such as mutton f a t , human fa t , milk, butter,

eggs, muscle t issue, l iver , kidney, brain (Thomson and Abbot, 1967).

Special problems are presented i n the analysis of water samples fo r pesticide

residues (US Department of Inter ior , 1969). Water normally contains l iving organ-

isms, suspended solids, dissolved minerals and organic matter, and these materials

affect drast ical ly the s t a t e i n which pesticides e x i s t i n water. A possible method

is t o extract 'water samples with an organic solvent which can l a t e r be evaporated.

The efficiency of this procedure is rather low. A be t t e r method of removing and

concentrating pesticides f o r analysis is t o adsorb them on charooal, but this again

removes only a part of the residues from water; moreover, there is as yet no

method f o r completely desarbing the pesticide from charcoal. Another problem

i n the pesticide analysis i n water i s . the interfer ing substances which mw cause

analytical methods t o yield resul t s which are too high.

Clean-up procedures are required t o make the f i n d extract suff icient ly

purified In order t o minimize possib2e interferences i n the last analytical step.

There are three main types of clean-up: c o l m chromatograph;r, solvent par t i t ion

and th in layer chromatography (Thornson and Abbot, 1967). Chromatographic techniques

using F l o r i s i l adsorbent (15% MgO; 84% si02) have proved very successful i n the

analysis of chlorinated hydrocarbons. An attempt was made t o devise a general clesn-

up method by u t i l i z ing a gas chromatography appmatus without detector (Zweig, 1961).

Another new approach t o a general clean-up has bean tke sweep co-dist i l la t ion

technique fo r pesticides i n o i ly crops (Storherr e t al., 1967). A s a general

approach it has been recommended, particularly for crude plant extracts, t o attempt

flrst an acetorli tri le part i t ion, followed by F l o r i s i l chromatography and ges chmma-

tography. Each of these techniques has been used successfully i n the analysis of

different pesticides i n various environmental samples (see e.g. Zweig, 1970, f o r

a review).

The method of choice is, however, the gas chromatography which w i l l be

described here i n some more de ta i l . The great majority of pesticide residue analyses

today are performed by gas-liquid chmmotography using detectors with the highest

sens i t iv i ty o r select ivi ty. Pyrex glass columns have largely replaced the older

columns made of s ta in less s tee l , copper o r aluminium. An acid-base washed sil icon-

ized support, Anakrom ABS, is recommended fo r general use i n pesticide analysis

(Burke, 1965). The preferred stationary phases are Dow-Corning-200 o i l (1M by

weight) or a mixture of DC-200 and 92-1, a fluorosilicone grease (Zweig, 1970).

The choice of the stationary phase w i l l depend on the compound to be analysed.

Some examples are given i n Table 4.

For pract ical reasons the choice of car r ie r gas is limited t o helium,

a s o n , carbon dioxide and air. The detectors used include electron capture, flame

ionization fo r phosphorous, microcoulometry, flame photometry anddectrolyt ic

conductivity. The approximate working sens i t iv i ty of selective detectors is shown

i n Table 5.

STATIONAFiY PHASES FOR GAS CHROMATOGRAPH!! OF PESTICIDES*

(SOLID SUPPORT: JWAKROM ABS)

_ _ _ . _ _ - - - - - - - . _ - _ . I . _ .. . _ _ _ _ _ _ _ -.-" . . . - .-_. - , . . . - Pesticides Stationarf phase

_ _ _ _ _ . _ _ . _ _ _ - . _ ..- .__. .___. . ..-- _ _ _. . - ..__.._. . " ..-- I-

Phosphates 1 - % SE 30 (0.2% Versamid)

l*DC 200

Chlorinated pest ic ides 10% DC 200

Triazine herbicides 57 Carbowax 20 M

Pyrethrins 5% SE 3 3 plus 5 % &F-1

Carbarnates 8E200

Phenoxyalkyl e s t e r herbicides 20% DC grease

TABLE: Li

APPROXIMATE WORKING SElJSITMTi OF SEIECTIVE DETECTORS*

- -- ..- . .---- . .-, -- . . . . -- - - . - - - - - - ... .- -. - - -

Detector Detected Range

Microcoulorneter C1, Br, I, S, P 0.1 - 1 g

Electron capture Chlorinated 0.1 - lng

Sodium themionic P 1 . 0 - long

Flame photometer p,s In@;

Elec t ro ly t ic conductivity Chlorinated o r sulfur, 10 - 100 ng

* Source: Zweig (1970)

Probably the greates t s ingle s t e p i n increasing the de tec tab i l i ty of

chlorinated hydrocarbon insect ic ides was the development of electron capture de-

t ec to r (Lovelock and Lipsky, 1960), based on tk following principle: A mdio-

act ive ,&emitting source ionizes the inolecules of the ca r r i e r gas (nitrogen) t o

produce slow electrons which migrate t o the anode under fixed potent ia l producing

a steady current. I f the compound t o be detected and measured i s an electron

absorber, t he current is reduced proportionately t o the amount aqd the electron

a f f i n i t y of the substance present. The radioactive source may be tritium (eg.

titanium t r i t i d e ) o r ~i-63. The electron a f f i n i t y of d i f fe ren t compounds var ies

great ly as shovm i n Table 6. (Zweig, 1970)

Compound

Hexane

Lead te t rae thy l

2, 4D

Malathion

DDT (P,P')

Aldrin

Carbont e t rachloride

Quantitive determination of pesticides based on re tent ion curves a r e

re la ted t o standards put through the gas chromatograph. The only absolute method

is based on microcoulometry. Fig. 3 shows a typical separation of chlor3nated

hydrocarbons using gas -l iquid chromatography. . (Thornson and Abbot, 1967)

-- * W = Deflection uni t of t h e instrument

The electron c ~ p t u r e detector is uoC .- particularly suitable for

orga~iophosphoroue cumpounds. Kuch brtter results are obtained with ~liermionic

detection systems which are based on the fact that differeni a l k a l i metals in

the hydrogen flame ionization detector enhadce the response from halqgen and

especially phosphorous compounds (Karmen, 1964,Giu-ffrida , 19643. The effective-

ness of this type of detector is illustrated in Pig, 4. (Zveig, 1970)

------.-- .--. *--., -....- --.----

I I. BFIC 25 ne i

Z Hcpochlor 25 nc 2 . . .

3..~cf&;ia 2.5 rig '

4. liepmchlor cpXIdc 1.5 ng

5. bduulfan k 25 ng

4 Dieldrin 2.5 ng

F~c. k .>~~.@!?sis OF 1 pg GA*:I* of liit~l.s~~c, piir.tt!~i&~. and r~cch,! ~ ~ c : ; w i i w I, , t.4) h y

7. E & I ~ k5 ng

5 8. TDE 6'5 ng

UW! " 3 14 t2 10 8 6 4 2 Mi*-

L . . 1 Fig. 3 - Separation of cigiit organa-&i*xine :comp~uhds

Flame -photometric deteetbr' (Brody and Chaney, 1966) i s specific fo r

organophosphat- oe.: organosulfur, comp~unds . When S- and PT containing substances

are-.burritCin a hydrogen rich'flame, a characteristic flame emission occurs which

can be. ;separat@d eas'i.1~ by. .na.rr~w-band. interference f i l t e r s .

EIec~1- ic~condu~t iv i ty a f e c t o r may. be used fo r nitrogen containing compounds.

The effluents f romthe gas chromritography column are passed through a pyroliser

i n a hydrdgen atmosphere with Ni-wi?e catalystconvertingorganic hilt-rogen t o

ammoriia, wfiich is detected by measuring changes i n conductivkty between two platinum

electuodes. .Small quanti t ies (20-40 n g ) are well resolved with such systems.

I n microcoulometric gas chromatography (Coulson e t al., 1960) the gas chromato-

graphy column is c o ~ e c t e d ' t o a combustion tube under oxidizing (for halogens) o r

reducing conditions ( for phosphorous). The gases are then passed in to a coulometric +

system where ~1-, ~ r - and 50 are t i t r a t e d with Ag electr ical ly. gemrated. The 2

t i t r a t i n g agent i s kept at a fixed concentration during the t i t r a t ion . The area under

the t i t r a t i o n curve is proportionate t o the amount of s i lve r ions generated atxl

can be related theoret ical ly t o the absolute amount of pesticitles tha t passed through

the chromatographic column.

The analysis of environmental samples f o r mercury is a complex problem. The + sensitivity,needed i s at l e a s t 0.1 ppm with accuracy, Tf possible, t o wlthin ' 1w. Good methods have been developed i n Sweden, Denmark, Finland, USA and Japan f o r

the analysis of f ish, other foods and body t issues f o r t o t a l mercury by:activation

analysis and atomic absofption, and for methylmercury and other organic memury

compounds by gas chromatography. Less developed are methods f o r mercury determination

i n air and water.

W-thisone method is relat ively ins&siti:ve requiring large samples; i n addition

it has t o be handled by very experienced chemists. Suitable procedures f o r t o t a l

mercury have been developed -if i Sweden (Borg e t a.. , 1969), Japan (Xrukayama e t al.,

1%1; Tsinghaki e t .al., 1967) and USA (AOAC Methods of Analysis .. 1965). Di-thizone

nethod has been used fo r water analysis.

Neutron activation methods are now widely used fo r t o t a l mercury determination. 12

n/cm 2

After neutron i rradiat ion (2 - 3.@s at a thermal reaction f lux of 10

second) the sample is decomposed hy boiling with n i t r i c and su l fur ic acids,

and mercury d i s t i l l e d off a f t e r addition of perchloric acid and glycine, as a

vo la t i l e compqmd. The mercury i n the d i s t i l l a t e i s then deposited on gold f o i l

and the Hg-197 determined by gamma spectoscopy (SJijstrand, 1964). This method +

has a precision of - 2%. Other neutron activation procedures have been proposed

i n Finland (Hishen, 1970) and Yugoslavia (Kosta and Byrne, 1969).

Atomic absorption a l so measures t o t a l mercury, Itjs comparatively simple, rapid

and cheap. A l l the mercury i s converted in to elemental mercury vapour and the

amount present determined by measuring the absorption of radiation from a mercury

lamp ( a t 2537 A). Sens i t iv i ty is good ( 0 . 0 1 ~ ) but the precision and accuracy

a re moderate (Brandenbergex- and Bader, 1967, Lidurns and Ulfvarson, 1968, Linstedt

1970 1. Gas chromatographic methods are available (West88 , 1966) f o r determination

of methylmercury i n a:wide var ie ty of samples a t a sens i t iv i ty of about 0.0001 ppm

i n f a v ~ u r a b l e cases. The method can d i f fe ren t ia te methylmercury, ethylmercury and

metoxy-ethylmercury, phenylmercury, aml dimethylmercury. Homogenized samples of

f i sh , f o r exeunple, are extracted withbnzene a f t e r addition of concentrated

hydrochloric acid. Separation frcm i n t e r f e ~ e n c e s is achieved by complexing with

aqueous systein acetate and re-extracting strongly acid solution with small volumes

of benzene. Columns of Carbowax 20 M o r Chromosorb W operated a t 180' are used

f o r chromatographic separation (Study Group on Mercury Hazards, 1971).

Other techniques applicable t o current problems of mercury pollution are

X-ray fluorescence and polarography of organomercuric compounds.

Transport processes i n the environment +

An attempt t o sumukize the cycling of pers is tent pesticides i n the environ-

ment has been made i n Fig. 5 (~dwards, 1970).

The form i n which the pesticides are being transported i s not always clear ,

but very often it is a s a sorbate on col loidal par t ic les or a s aerosol droplets.

The source of pesticides t h a t are thus transported by wlnd ax% water has t o be

identified. They W i l l often a r i s e from t rea ted areas. Wind ard water erosion of

s o i l exposed t o chemicals can r e su l t i n cataminat ion of air ard water bodies

through suspension andimwement of col loidal par t ic les .

* This section is based on: Freed, V.H. (1970)

Pig. 5

It i s probable tha t th is is a usual way by which sources of water supplies are

contaminated. It is less l i ke ly tha t the coc tz~ ina t ion ar i ses through leacti-g ir.t

gxound weter since many pesticides have a very low water so lubi l i ty and high a f f i c i .

for colloids.

Another means by which a pesricide applied t o o r confined within a given area

might become a contaminant, par t icular ly of air, would be through vapourixation.

Though many of the pesticides commonly used have low vapour pressure, when m

extensive surface of these chemicals is exposed, appreciable amounLtr of vapour get

i n to the a i r . These vapours i n turn can condense OII col loidal par t ic les suspended

i n air or c'oallesce in to aerosol droplets, and thus em be transportedever consider

distances. Pf during the course of t h i s transport the chemical reaches an inter-

face with a living system, partioning in to the l iving system w i l l occur. The

quantitative relationships i n mass t r awpor t of chemi-cals i n a i r or sizable bodies

of water is only poorly understood.

Whenever pesticide6 are released or expelled into the environment, they

encounter a variety of sorbing surfaces, ranging from the surface of an orgatism

through the variety of e r ~ a n i c and inorganic colloids siztting i n the enviranacxt.

behaviour of chemicals i n the environment and as a mechanism of reducing biological

avai labi l i ty . The extent and strength with which a chemical is sorbed depends on

the properties of both the chemical and sorbing surface. A very good approx-

imation of the strength of sorption and the subsequent mobility of t he chemical

from the sorbed s t a t e can be d e d u c e d f m t h e enthalpy of solution. A more precise

evaluation i s given i f t he enthalpy of sorption i t s e l f i s measured. The extent

and energy of sorption thus determines the ease and amount of leaching, biological

ava i lab i l i ty , vapourization, and t o some extent ra tes of degradation. This holds

t r u e whether t he sorbed chemical is I n so i l , water o r air.

Of r e a l concern with pesticides i n the environment is whether o r not they

ex i s t at concentrations suf f ic ien t t o have biglogical effects . This e f fec t may be

e i the r d i rec t ly on the organism as a primarji toxicant o r it may be a subt le i n t e r -

action with another s t ressor o r s e t of s t ressors o r the e f fec t may be even more

indirect,, I n the l a t t e r case, one ismncerned with whether a chemical, by a l te r ing . ~

any component of t h e environment, par t icular ly the biota, may r e su l t i n an environ-

ment more hos t i l e t o the health and welfare of man. Because there is an in te r -

relationship between concentration and time of exposure, the persistence of chemical

i n the envimnment becomes a fac tor of ance rn . Two types of processes are involved

i n reducing biological concentration of a pesticide i n a given volume of the environ-

ment. The first type of process is t h a t of adsorption and physical transport. The

second type of process i s that which r e su l t s In a l te ra t ion of the chemical, hopefully

t o an innocuous form. The l a t t e r type of processes involve photolysis, chemical

degradation a x l biologic degradation. Pract ical ly a l l organic chemicals are subj,ect

t o one o r more types of degradation processes.

The r a t e a t which a pesticide undergoes a l te ra t ion varies markedly with

conditions and the nature of th? chemical. However, extensive studies have indicated

that these degradation processes follow known r a t e laws. Thus cer ta in parameters

may be determined f o r the degradation of classes of compounds and thus used t o

estimate.,the probable persistence of a pesticide under a given s e t of conditions. ..: .

It was indicated tha t there is a dynamic transport of pesticides across in te r -

faces of components of the cosystem. The amount of chemical parti t ioned i n any

instance is determinded by tk volume or extent of the components invalved, concentra-

t i on gradients, and a variety of other factors. For example, there is indication

t h a t t he higher t h e l i p i d and so l id content of the biologi'cal system, the greater . , ~ . . ..

w i l l be the accumulation of the chemical by parti t ioning. Thus w i t h organochlorine

;ubntnncc..~,- ci 'mot drop lox i n o i 1.s 3; 1.1 ~ rnir?ly, f.f e-;oi:, a:.c~~ni.~il.ii", c o a ? ~ i i ? ~ r ' . t ~oT..':>

greater than one t o five times that of the environment, whereas s% orgari:;sm having

a low water coatent and a. higher 1 . ip id c.nntr?llt may concentretc the cltcn~icej by

a thoueand fold cfirectly from i ts environncnt..

O ~ a n o c h l o r i n c insecticides - -..- -+-------------

The l e v e l s of di f ferent organochlorine i n c e c t k i d e s in the cnviroilment varg -6 within wide limits. For DDT for exaaplo they mayr-ange.from 10 ppm ( b e & water

or air) up to 10 ppm (some predatory birds) . Q~~cal-cbncentrstion of DDT in

di f ferent anlironmenta'f. smples are slrown i n Figure G-(Edwards, 1970).

m fstirnato based on very t r w lampl?s ? -1nsulliciint data svailable

Data on levels in air are. very scarce. Concentrati.ons~ found a t some distance

from the point of applicrbtion are-usuelly very low. The majtazity of e~mples ~nslysr

i n the United States by Tabor (1966) showed DDT levels i n the range from 0.1 - 400 ng/m3 . Abbot e t a l . (1966) fbund DDT and i t s metabolites i n London a i r i n

3 concentrations of about 10 ng/m . Some of the available data have been summarized

by Galley (1971) and are shown i n Table 6 ,

TABLE 6 DM' AND RELATED COMPOUNDS I N A I R

4

5 Agricultural with formulating plant

Before spraying

After spraying

Non-urban (lake s ide)

Large urban with Pest Control Programme

-- Type of Environne n t

Agricultural

Pesticides may enter air when applied by spraying or by vaporisation of residues,

stock materials o r wastes. Other sources are aerosols produced i n manufacturing

processes, burning of "empty" cofitainers or f i r e s i n warehouses. Winds,will a lso

disperse pesticide residues tha t are absorbed on dust part ic les . The dis tr ibut ion

of airborne pesticides depends heavily on meteorological a n d i t i o n s and on par t ic le

s ize. Airborne pesticides are l ike ly t o decompose rapidly under the influence of

light and ul t raviolet radiation. The residues found i n a i r do not seem t o present

any significant health hazard f m m inhalation. Tabor (1966) has calcualted tha t

t h e average intake of pesticides by inhalation of ambient a i r i n th United States

would not exceed 2-32 +day. On the other hand, it has been suggested tha t about 4 2.4 x 10 tons of DM' are transported yearly t o the oceans by ra infa l l , and t ha t

"a t leas t half of the t o t a l amount of DDT ut i l ized enters the sea through the

atmosphere'' (wAMP, 1971). Thls suggestion has not been generally accepted.

ng/m3

0.1-7.6

0.1-1.3

Galley (1971) condiudes, f o r example, tha t "although it has been shown without

reasonable doubt t h a t insecticides, including 'Dm, are present i n the air i n some

parts of the world and can be carried by the great moving air masses over long

distances, as are some small insects, the amounts which reach the earth from this

source, ei ther by fal lout or i n rain, are extremely small and i n those quantities

without any hazard t o man, his domestic animals, h i s .food o r t o wild l i fe".

Surface and ground water may be coeaminated by pesticides from aer ia l

applicatilsn,, run-off from. treated areas, percolation through s o i l t o ground water,

waste discharge by pesticide producers, misuse o r through accidents. The available

da%a indicate, that pesticide levels in different water bodies are i n the r q e from

O , O O 1 ~ l t o I r / " g / l l Pesticide iesidues i n some water surveys i n tk United . ,

States and i n - the United Kingdom are summarized i n Table 7 (Edwards, 1970, Galley,

1971

7 PESTICIIE . . RESIDUES . : I N WATER SURVEYS

h United States Department of Agriculture.

DDT and II! 4 1 tB#E; "Om-

Max. I Mean

United States of Americs, -

Reference

.

I I United Kingdom I

No. of Type of water s i t e s I

f

.Breidenbach e t a1. (1967)

USRA~' (1966)

Green e t al. (1966)

Wanlick e t a1. (1966)

Keith & Hunt (1966)

Weaver e t al. (1965)

Brown & Nishioka (1967)

L?: Dm, DIE, DDD

I

Holden & Marsden '(1966)

Lowen et al. (19'i'l) 11

I t .

99

10

109

4 8 82

97 11

- 21

9 7

130.0

800.0

!X@.o 15.0.

Sewage ef f luents

Sewage effluents'

Yorkshire r ivers

Bri t ish r ivers

112.0

Major r iver basins

Mississippi r iver deltr.

Major r ivers

36.0

130.9

64.6

1.6

149.0

720.0

127.0

Water areas (Utah)

Water areas (California

Major r iver basins

Western streams ---- -- - - --

32.4 22.0

, 0.62

102.0

145.0 10.3 - - -

It is important t o note, however, tha t there is a considerable difference i n

concentration found i n the water phase, i n suspended paI-ticles and i n th bottom

sediments, as i l lu s t r a t ed i n Table 8 (Edwards, 1970).

DISTRIBUTION OF PESTICIDES I N A LAKE

I -

I I ---

I Average residues ( G g e s i n p a r e n t h e s e s ) I

Very 'pew analyses fo r organo-chlorine pesticides have been carried out on sea

Phases

water, ard the levels found were generally very low (~0.000001 ppm) except i n the

coastal areas near the mouth of rivers. For example, it has been es t imatea tha t the

San Joaquin r iver contributes lgOO kg/year of insecticides in to San Francisco Bay.

A similar calculation suggests tha t the Mississippi carr ies 10,000 kg/year of inixed

insecticides in to the Gulf of Mexico (Risebrough, 1968).

A s pointed out i n the International Standards fo r Drinking Water (1971) "exper-

No. of samples

ience up t o now supports the.genera1 opinion tha t the residues of pesticides tha t

may occur i n community water supplies, mostly of the order of a few inicrograms per

l i t r e , make only a minimal contribution t o the t o t a l daily intake of pesticides f o r

the population served".

C -. -

Water 82

1 par t ic les (ppm)** 33

Acute pollution of r iver and other water bodies by insectibides can occur

accidentally, as was the case i n tk River hind i n 1969. By the w d of June it was

noticed, f i r s t i n Germany and then i n Holland, tha t fish were dying i n large amounts

DM' & related compounds

0.62 (0 - 22.0) 14.74

I 1 Bottom Sediment (ppm)**

i n the river. Apparently, f ive days before the Dutch authori t ies were warned about

the toxic substances i n the Rhine r iver water, the German authorit ies observed near

39

the town of -Bingen dead fish; ducks and rats . Investigations camied out both i n

Holland and Germany could not establish the exact source of the pollution, but it

BHC

0.01 (0 - 0.15;

0 (1.8 - 78.0) j

4.44 (0.01 - 94.0)

i i

0.03 (0 - 0.30

Toxaphene

0.02 (0 -/0.32I

0

4 I

Dieldrin

- Heptachlo

-

i s probable tha t a quantity of about 150 kg of endosulphan was dumped in to the

r ive r water. Another possible source was the waste from a plant producing t h i s insect-

ic ide but this was l a t e r dismissed as unlikely. This incident was important because

the Rhine is used as a source of drinking water. However, a t no t i m e during the

accident was it necessary t o stop the operation of the waterworks; f i sh t e s t s and

other analyses showed that there was no danger t o the public health. Agricultural

users were also concerned about the ef fec ts on crops, particularly i n Holland where

water from the W n e is used t o prevent the intrusion of sea water in to low-lying

areas.

Analyses of th? t issues of a number of specimemof marine and freshwater organisms

indicate the presence of organochlorine pesticides a t levels exceeding the concentratton

i n water up t o 10,000 times. It appears that prolonged exposure t o water containing 10 DDT or dieldrin i n concentrations exceeding one part in 10 - (O.l,ug/l).c~t-istitutes

a significant hazard t o eeshwater and marine f ish. ( k r i c u l t u r a l Research ~ o u n h i l ,

1970 ) . The presence of organochlorine residues i n the cultivated s o i l i s direct ly

related t o the amounts applied. The question i s how deeply they penetrate and how

long they persis t . A study i n the United Kingdom showed that when applied t o the

surface BHC had a ha l f - l i fe of about five weeks, clieldrin about nine weeks and DDrT

about 18 weeks, but when they were worked in to the s o i l , the ha l f - l i fe increased t o

about 15-20 weeks fo r BHC, 4-7 years fo r dieldrin, and an estimated 5-8 years f o r

DDT; it would take about ten years on the average fo r 95% of DDT t o disappear, the

r a t e of degradation being higher a t higher temperatures (Agricultural Research

Council, 1970).

Organochlorine insecticedes have beenfcund i n untreated s o i l as w e l l ; -the levels

found i n England were of the order of 0.05-0.3 m&; an average of 1.6 mg& of

DDT and related compounds were found i n untreated deselrt andpra i r i e so i l s i n Texas,

Similar or s l ight ly higher values (0.02tu7 &kg) were registered i n s o i l s of

Central Asia (Zahidov ard Atabaev, 1965). The source of pesticides i n untreated soil

i s probably r a in fa l l o r dry fal lout .

Soi l residues do not ooncentrate i n plant t issues but do so i n th bodies of

invertebrates tha t l i ve i n the so i l , and can be transported in to bodies of higher

organisms. Pesticides appear t o influence the number of inve r t eb~a tes i n soil.; many

insects and larvae are k i l led but the number of some animals of the microfauna may

increase because t h e i r principal predators are killed. The concentration factor i n

ear th worms i s usually about 2-6 fo r DDT and related compounds, but it may go up t o

70 (Galley, 1971).

Since &-ghochlorine residues disappear so slowly from s a i l , they do not

contribute much t o gaound water levels of pesticides. Even in. .areas used fo r orchards,

the ' insec t ic ides of tha t type could not be detected i n ground water ( ~ ~ r i c u l t u r a l

Research Counail, 1970).

The leve ls of organochLorineinsecticides were found t o be par t icular ly high i n

cer ta in ipecies of birds. The concentrations may be suf f ic ien t ly high i n predatory

b i rd populations t o dis turb cer ta in metabolic funtions, causing par t icular ly a delay

i n the onset of sexual maturity and thinning of eggshells. DDT i n the environment

must be therefore regarded a s a s ignif icant hazard t o predabry bird populations

(Agricultural Research Council, 1970).

Organophosphomus insect ic ides

A survey of s i x English r ivers i n 1968 showed the presence of an organophosphorous 9

compound (~a rbo~hen th ion ) at a concentration of 8 par ts i n 10 ; other organophosphorous 11

compaulds were detected at much lower concentrations of about 7 par ts i n 10 . Although such compounds are not pers is tent i n water, two ser io ts accidents have been

recorded i n England with mecarbam; i n one case fish were eliminated along l2 'miles of

r i v e r and damaged i n over s i x fur ther miles (Agricultural Research Council, 1970).

Organophosphorous compounds are sometimes d i rec t ly applied t o the s o i l t o control

s o i l inhabiting pests. Some of them are rapidly degraded by hydrolysis. Ot~lers are

oxidizad, forming a se r i e s of compounds which a re much more act ive inhibi tors of

cholinesterase, but i n generalnom of the organophosphorous compounds w i l l pers i s t

i n s o i l longer than about 6-8 weeks.

Herbiaides

Herbicides are deliberately applied t o surface,water t o control aquatic weeds; i f

used excessively, weed k i l l e r s may reduce the oxygen i n t h e water so far as t o

endanger animal l i f e . Some herbicides, f o r example MCPA, 2,4, -D and 2,4,5, -T may

be found i n ground water because they are readily leached out of so i l s .

Organic Mercury

It is d i f f i cu l t , except under specified circumstances, t o r e l a t e mercury leve ls

i n environmental samples t o the use of organomercury f'ungicides. Mercury occurs

naturally i n the human environment; the annual erosion and weathering i s estimated t o

contribute some 5000 tons t o the sea. Another 4-5OKI tons of mined mercury (about

half the annual world production of 9000 tons) are l o s t t o sea, s o i l and the

atmosphere (Goldberg, 1970). Man-made sources of mercury include mining and re-

fining processes, chlorine-alkali plants, pulp ' a d paper, plast ics and electronics

industries, hcspitals, agricultural practice and drugs. Burning of foss i l fuels

appears t o add.large quantities of mercury t o the environment; coal may average

between 0.5-3.3 ppm mercury (Grant, 1971). Mercury. is discharged in to the environ-

ment as metallic, mercury (chloralk+i plants, foss i l fuel combustion, incineration

processes, mercury containing i n s t m e n t s ) , as inorganic mercury compounds (chlor-

a lka l i plants, bat ter ies , . catalysts) op. as alJsyl-, alkay-, or other organic

mercury compounds (methyl-ethyl mercury - ,agriculture, various chemicals, paints;

methow-ethyl mercury - agriculture; phenylmercury - paints, pulp and paper industry). . .

Once i n the environment, mercury compounds are capable of a .variety of transform-

ations.

Concentrations of mercury i n a i r are low; i n large industr ial c i t i e s 24-hour

averages may appraoch l / u g / m 3 (US Environmental Protection Agency, 1971). Typical

values of mercury concentrations i n surface sea water are 0.13-0.15 /dl (FAO, 1971),

i n rain water about 0.5&l (Study Group on Mercury Hazards, 1971), and i n surface

waters generally well below l&l (WHO 1971). Infomationis inadequate t o ascertain

what proportion of mercury i n water o r other environmental media i s i n the form of

methylmercury. Analysis of cultivated a d u ~ u l t i v a t e d aoil In Sweden proved that

the seed treatment played only a minor role i n the mercury levels i n soi l , although

about 80 tons of this mercury compound was distributed i n Sweden between 1940 and

1966. Studies on biodegradation of mercury fhg tc ides showed increased levels of

mercury i n the top s o i l a f t e r the use of alkyl mercury compounds. I n mntrast,

phenyl mercurykpenetratee easily in to the deep layers. Residues of mercurial

fungicides are firmly bound i n the s o i l and only a small portion is leached into

surface waters. Moreover, they can be decanposed and volatiZized by microbial

aotion.

I n water, ionized forms of mercury are bound rapiUly t o suspended organic

matter and sediment. The ad-sorption of alkyl and arylmercury is mfavourably in-

fluenced by very high or very low pH. Ihe inajor part of a l l forms of mercury

accumulates f inal ly i n the bottom.seiiiment.

Zeve-ls - of .mercury found i n fish In a ntb ina ted areas (several milligrains

p e r m ) exceetled considerably the levels i n water from 'Which f i sh samples Wre

obtained. Concentration differences of several orders and magnitudes are established

between mercury levels i n water and mercury content of f i s h (Johnels and- Westermark,

1969). Pract ical ly. all mercury i n f i sh is i n the form of mwthylmercury (c. f . WestZld,

1966). Japanese -studies. showed .that fish may contain high levels of ethylmercury

as w e l l , probably due t o the extensive use of t h i s fonn of alkyl mercury f o r seed

dressing (Ueda, Aoki and Nishimura, 1-971). Marine f i sh accumulate methylmercury

appmxlmately t o the same extent as fresh water f ish.

High levels of mercury were found i n t issues and feathers of predatory birds

l iving predominantly on f i sh . Significant levels of mercury were also found i n f i b -

eating aquatic animals l i k e ot ter , mink and seals. I n several countries increased

levels of mercury were also found i n seed-eating species of birds, such as pheasants,

i n birds of prey, l i k e owls and falcons, i n s m a l l seed-eating rodents and other

terreskrial mamals (c. f . Vostal, 1971). The extensive use of alkylmercury fo r

seed dressing presents obvious hazards t o wildlife. Among the ef fec ts observed are

increased mortality, reduced hatchability i n birds and a high frequency of malfom-

ations. The levels of-mercury i n birds and t h e i r predator8 decreased considerably

when the use of alkylmercury compounds was res t r ic ted i n Sweden.

Important translocation of mercury has been observed only i n f o l i a r merc iq

treatment, f o r instance when used against blast i n Japanese r ice, i n tomatoes,

pears and apples (c . f . Study Group on Mercury Hazards, 1971).

Disposal of pest i cidebd c o n t ~ l of en~>-~~~aJpo~lutuo~ -- Environmental pollution may ar i se as a consequence of the application of pest-

icides, from uncontrolled disposal of pesticides o r wastes containing pesticides,

-3 through accidents. The problem of minimizing pollution ar is ing from the applica-

tion of pesticides can be approached i n several ways ( c . f . American Chemical

Society, 1969) :

a) Use of minimum amount of pesticide. The amount of pesticide used can be

decreased by reducing the number of scheduled treatments, by applying only the amount

needed f o r effective control, or by treating, when possible, only areas heavily infested

by pests. For example, cotton is often sprayed every five, seven o r ten days. By careful

monitoring of insect population, it i s possible t o reduce scheduled treatments t o the

minimum necessary. The number of applications can also be reduced by determining the

period which i s c r i t i c a l f o r treatment. Sometimes it may notbe necessary t o aim a t a 100

per cent insect control; 75 or 80 per cent may suff icient t o prevent a decrease i n the

y ie ld or quality of a crop. An example f o r the th i rd approach, i .e . t o t r e a t only

areas that are heavily infested, is the experience w i t h spruce budworm in the Salmon

National Forest, USA. A study showed that the target insects could be effectively

controlled by treating less than 10 per cent of the entire area (Casebeen, ~964) .

b) Modifi~ati~on of application eauipment. Improvement 15: desirable in aerial

applications, and particularly in the application of dust f emulations . In meny

cases, clw separates from the pesticides during applioation, resulting in non-

uniform deposits. The consequence is that larger quantities or repeated applications

are needed to achieve the same result. Several proposals hake been made recently

on how to improve dusting equipment, Good results have been obtained with electro-

static equipment W c h produces charged particles (Harrel et al., 1965). Another

promising innovation is the uae in aerial applications of low volumes of highly

concentrated insecticide formulations. The low volume technique has been ws4,for

example, to treat the boll weevil with malathion (brges, 1965). It is obvious

that the development of better application equipment requires a close collaboration

between entomologists, agricultural engineers, ohemists and applicators.

c) Modification ------ of formulation. -- -- The use of various additives (resins, cellulose

ether polymers, etc. ) for liquid fomulations may heap to reduce vaporisation and

losses of pesticides by washing off by rain, Additives may also improve the perfom-

ance of speoific insectictdes. For example, quaternary ammonium salts added to

Zectron formulation increwed the uptake of the insecticide by cotton plants, t.h~3

reducing the dose and increasing the effectiveness of the treatmeat (Matheson and

Taft, 1964). Other modifications of formulations that have groved effective In re-

duaing the dosage of some insecticides include the use of granules instead of fine

powders, and the application of liquid gas aerosols. Aerosol particles seem t u stick

tenaciously to p u t surfaces gnd are not removed by rain. (Ditman et al., 1946). dl m e u s e a o ~ e ,effecti~Q&3ticide~. Great effort is be- made in

countries to improve the specificity and effectiveness of pesticides, by introducing

entirely new chemicals, or by applying them jointly with varisus synergists.

e) Ilhe use-of - alternative non-ehem%cal ---- methods .*f pes_t control. This is of

course the most efficient method for preventing plXution.

Methods c ) arvd d) are discussed in more detail in otber lecfures of the Seminar.

Two recommgndatiqts of a subcommittee of the American Chemicals Society (19@)

are part,icula~ly pertinent to the problem of minimizing the pollution arising f m ~ ~

EM/SEM. HLTH. HAZ . PEST/14 page 28

the application of pesticides, and are quoted here:

1 ) "An extensive educational programme at all government levels is

required t o teach a l l pesticide users the optimum methods of

pest control".

2) "persistent 'pesticides should only be used i n minimal amounts and

under conditions where' they have s h o k not t o cause widespread con-

tamination of the environment. Where possible, highly persistent

materials should be replaced".

The other important source of 'environmental pollution by pesticides is the

unconti-olled disposal bf unused pesticide formulations o r containers, and of l iquid

o r so1id"wastes from agriculture or industries using o r producing pesticides.

The choice of an appropriate disposal method depends t o a large extent on

the chemical characteristics of pesticides contained i n the wastes. For example,

disposal o r treatment processes tha t are applicable to'wastes containing organophos-

phorous compounds may not give satisfactory resul t s i f the wastes contain organic

mercu'iy compounds, br orga&chlorine insecticides. A l l pesticides ao ntaining

waste should be considered as toxic wastes and handled accordingly.

A frequently encountered problem is the disposal of small quantit ies of wastes

containing pesticides. For example, farmers may be l e f t with containers which still

contain residues of pesticides, gardeners with half-used t i n s o r packets of pest-

ic ides and so on. Often such wastes do not present any problems, but occasionally

they may give r i s e t o Bjff icul t ies . Where there exis t s i n the vicini ty a t i p fo r

indus t r ia l wastes, including toxFc wastes, small quantit ies of pesticides containing

sol id wastes may be safely disposed of at the t i p , particularly i f it is covered.

The owner of the waste should, of course, notify the local authority or the contractor

about the natureandquantity of waste i n question. Surplus small amounts of pest-

icides can be, i n some cases, tipped with domestic refuse, provided the t i p is large

enough, properly located, properly operated and receives a fair amount of waste.

13umpi& of pesticide containers *or surplus amounts in to water aourses may cause

serious pollution and should not be practised. The same applies t o flushing of

pestlcldes down sanitary sewers. Other means of disposing of pesticides include

chemical destrmction (e . g. of organophosphorous compounds by alkaline solutions),

and disposal through waste systems equipped t o treat such wastes. Burial of con-

ta iners is also practised but it i s not a very satisfactory method. Special pre-

cautions might be necessary i n the case of surplus amounts of pesticides from farms

& large gardens (Technical Committee on the Disposal of Toxic Solid Wastes, 1970).

Well organized systems of collecting, recycling and salvaging.unused pesticide

have been in i t ia ted , fo r example, i n Sweden. (Study Group on Mercury Hazards, 1971).

Wastes and remnants are brought t o a comimity collection centre and then transported

t o the salvage centre. Paper sacks f o r pesticides have been designed so tha t the

openbng is destructive, and they cannot be re-used.

Incineration i s also used for disposing of bags, f ib re board dnuns, p l a t i c

containers and larger amounts of surplus pesticides. This should be.done in:'fYaSte

incinerators, i f they exist , o r by burning i n an isolated area. Cex3xxi.n precautions

are required, however, i n incineration. Weedkiller containers should not be burned.

Pesticides, l i ke 2,4-D, c m vo la t i l i ze before they are burnt, and the incineration may

then become an important source of environmental contamination. Moreover, pesticides

and defoliants may contain chlorates and may explpde when heated. .Generally,

tncineration as practised today 1s unsa t i s fac toq because the temperature i s ' t o o low

f o r pyrolysis (US Department of Health, Education. and Welfare, 1m). A special

problem is presentqdbymetal o r glass containers. They should be asposed of as

soon as possible t o prevent t h e i r use as containers f o r drinking water. The disposal . !

o r rinse water gives r i s e t o additional d i f f icu l t ies , and it i s perhaps best t o ship

unrinsed containers back t o the manufac-turers for disposal. Another method f o r

disposal of containers is ground burial , but t h i s is not satisfactory ei ther . More

de ta i l s on the disposal of pesticide containers m a y be found i n a publication issued

by the American Public Health Association (1967). The wastes of the pesticide manufacturing and formulating industries shou1.d not

be direct ly intmduced i n the receiving waters. The treatment required t o reduce the

toxicitjr of wastes varies with the composition of them. . Some compaunds may be re-

moved by conventional waste water treatment processes, others are more. resis tent . . .

Sett l ing basins are often used t o allow time fo r waste decomposition.and fo r controlled

release during the periods of higher flow. One of the most- twublesome types of waste

a r i ses from the production of 2,4 dichlom-phenoxy acetic acid. (2,4-D). The

chemical actually discharged i n waste is dichlorophenol. This waste was originally

treated by passing the waste water through a f i l t e r bed of activated carbon, at a

very high cost (Mills, 1959). Ws process was abandoned and replaced by the cheaper

alkaline chlorination process which produces an effluent containing about 25 ppsn of

dichlorophenol. In DM' production, %he crude DDT is purified by washing wlth large

quantit ies of water o r by neutralization d t h sodium carbonate. The resulting wastes

are highly acid, have a high content of organic matter, and are toxic t o f i s h and

bacteria. Treatment i n municipal biological treatmen& plants is possible but d i f f i c u l t

because of the hi& toxici ty of the wastes. The ot"ler method available is the con-

t r o l l ed discharge in to the streams or the sea. Biological treatment methods based

on activated sludge process have been developed f o r the treatment of wastes from the

production of organophosphorous compounds (Lue-Hing and Brady, 1968). Presently

available methods f o r t r ea t ing wastes from pest ic ide production o r use a re i n general

not sat isfactory, and it is very l i ke ly t h a t i n the ~ X t u r e advanced waste treatment

methods such a s t he adsorption on act ivated carbon o r chemical oxidation w i l l have

t o be applied t o supplement the conventional treatment. Sol id and concentrated

l iqu id wastes m a y be incinerated, but adequate i i lcinerator operation i s essent ia l .

In some instances, deep well disposal is a prac t ica l method, provided the geological

charac te r i s t ics of the area a re w e l l kr1ow;l and a re Tound t o be su i tab le f o r such.

The effectiveness of the removal of pest ic ides by standard treatment of water

f o r community supply depends on the type of pest ic ide and its concentration. The

most e f f i c i en t method fo r removingiraces of pest ic ides from drinking water seems t o

be the adsorption on activated carbon. Other possible methods, such as t he use of

other adsorptive media, ion exchange and se lec t ive membranes, require fur ther study

and evaluation (US Department of Health, Welfare and Education, 1969).

The transport of pesticides from the point of manufacture t o t he point of

application i s a source of accidental pollution. Specially designed equipment (cans,

trucks aad containers) is needed f o r transportation of large quant i t ies of pest-

ic ides , t o prevent t ha t mishandling which may r e s u l t i n accidental pollution. A

par t icu la r danger is the contarnination of food; simuHaneous shipment of pest ic ides

and foodstuffs should, therefore, be avoided. The packaging of pest ic ide products

deserves particv-lar at tention. . (c . f . US Department of Healih, Educati on and Welfare,

1969). The current pract ice of handling pesticide wastes is unsatisfactory even i n

countries which have a t r ad i t i on i11 waste managenlent. Moreover, the necassary

technology is not always available, and i f it is, it..may not be economical. This

is clear ly ref lected i n a recent Br i t i sh report (Agricultural Research Council, 1970)

which recommends that ."research bg done t o f ind economical ways of extracting o r

destroying pest ic ides i n wastes from indus t r i a l eff luents and from any other media

i n which they may occur i n higher concentration before being released in to the

environmenti'. The same report .further recormnends thatl'ways be s o w t of disposing

safely., and conveniently of pest ic ides t ha t are l e f t over i n containers". The Regort

on Pesticides and the i r Relationship t o Environmental Health (US Department of

Health Education and Welfare, 1969) also stresses the unsatisfactory situation

with respect t o the available methods for the control of environmental pollution

by pesticides, and recornends intensified research and development i n t h i s f ield,

i n particular as regards improvement of aer ia l and other methods of application,

treatment processes fo r the elimination of pesticides P r o m domestic water supplies

and from waste waters, and more suitable materials f o r pesticide packaging and

containers t o f a c i l i t a t e safe transfer, handling, use and disposal.

EM/SEM.HLTH.IIQZ.PEST& Annex 1 Page i

Abbot, D.C., e t al. (1966 Nature j '211. 259

Agricultural Research Council (1978) Third report of the Research Comnlttee on Toxic ChemicalsL London, HE30

Alg, D.PI, and Fairst , S.D. (1964) J. Bgr. Food Qem., 12, 541

iimerican C h d c a l Society (1969) Cleaning our envtronment, the chemical bqsis fo r actiw, Washineon D.C., ACS

American Public Health Association (1967) Safe Use of Pesticides, itew York

B ~ ~ , K,, H-tbzp, H,, Eme, K., e t a1..:..(1969) Viltm'JY, 5 301

Brady, S.S. and Chaney, J.E. (1966) J. Gas Chromatog., 42

Brandenberger, H. &d Bader, H. (1967) Helu.Ghim.Acta, 2, lbO? Breidenbach, A.W. e t - al. (1967) Chlorinated hydrocarbon pesticides i n major river basins, 1957 - ,1965, US Public Health Dept., 82, 139

Brown, E. and Nishioka, Y.A. (1967) Pest.ITon.3, L (2), 38

Burges, E.D. (1965) J. Econ. Entomol, 2, blh Burke, J.A. (1965) J. kssocr~ffic.Anal.~hemists, L8 ( 5 1,1037

Casebeer, R.L. (1964) 2ionttoring the 1969 Spruce Budworn Aerial Spray Prole* US Dept. Bgr. Forest Serv.

Coulaon, D.H., Cavanagh?. L.A., D e prier, J.E. and ~fal ther , 8. (1960)' . . J. A@. Food Chein. 8, 399

L.P., Goodhue, L.D., Smith, F.P. and i3urkharapi G. (1946) - J.Econ, &tomol., 39, 199

Edwards, C.A. (1970) CRC Tersastent pesticides in the' ehvironment, London, Butterworth

Egan, H., Hammond, E l J . and Thomson, J ., (1964) Analyst, 89, 480

F$f/SEM, HLTH.H!iZ, PEST/& Annex I Page ii

Federal !.rater Pollution Control Administration (1969) PTCA ?'Iethod for Chlorinated edrocarbon Pesticfdes i n ifater and %Taste Xater, April 1969, US Departanent of Interior, Cincinrdki, Ohio

Food and Agriculture Organization (FAO) (1971) Report of the Seminar on Liethods of Detection, Eeasure~cent' and f;oni.torin,z of Pollutants i n the Yarine Environment, Fk0, Fisheries Reports, $0. 99 Suppl. 1, R w

Freed, V.H. (1970) Chemodynamics-Trans,?ort and Behaviour of Chemicals in the Environmen~ Sub, task force on Food and 'Jater , Toxicology, Fd-3, Background document for the Report of the TaskVFoece on Research h h n i n g in Environmental ElrsaLth Sciences IJIE:kS, DHE:J, Research Triangle Park, 1J.C.

Oalley, R.A.E. (1971) The contribution of pesticides used in public-health programpes t o .the pollution of the environment I. General and DDT, '$Ho/U3~/71 329;~-Genev&

Gilfi.idda, . . L. (1964 ) J. Assoc .Offic.Anal.Chemists hJ 293

Goldberg,, E.D, ($970) i n Global effects of environmental pollution (S.F. Singer Ed.) Dordrecht, Holland, D. Reidel Publ.Co.

Oood~..rin, E.S., r~oulden, R.. and ~eynolds, J.G.. (i961) Analyst, 86; 697

Grant, N. (1971).~nvtrornlit;t i 3 (11) 2

Green, R.S. Gunrier,spn, G.L. and Lichtehberg, J.J. (1966)' ik A'griculture and the Quality of our' Environment, '?lashin,@n D . C. 8Cd~S I.

Harrel, E.A., ~ o q m n , 1.-.c.', bare, W.Y. (1965)' 3. 6con. Entomol, 71

Holden, V.A. and tkrsden, X. (19'66) J: Proc. Sew. hrif. & 295

K,, ~on8.0, T., Kai, P.et a l , (196 i )~umhoto Ped-J* % 157

Jensen, S. and Jernel'dv, A. (1968) -iiordforkk, 3&3

Jqhnels, BOG; and .5festermarck, T. (1969). i n Chemical Fallout (1,Uler. j.1.d. "Snd Berg, G.G., Eds. ), Sprin:@i&ld, '111. dd. Tho-ms

,Join$ Group of ,Exprts in Scientif ic +spec+ of, shrine Follution . (Wii1fP) (1971) Report of the Third Session, FAO, ~ o m e 1971, GESASP 111/l9

,LIP. and ,Riddick, .J.A.. (1952) f2nalYt- Chem...a, 589

Karmen, -4. (1965) Anal. Chem. 36, IU.6

Keith, J.O. and Hmrt;; E;%. (1966); Trans. 31st h e r . ".lildlife Rris.Conf ., 150

WJSE%!.~LTH~H~Z ,&T/& Annex I Page iii

Kosta, I,. and Qrlpe, i.R. (1969) Falanta, l.6, 1297

Lid-, V.V, and Ulfvarson, U. (1968) :lcta chem. Scand.. Zj 2150

Lovelock, J.E., and Lipsky, S.R. (lp60) J. ih.Chem.Soc., 82, 431

Inwden, 'G.F., Saunders, C.L., and Edwards, R.>J. (1971) Mater Reat.&m., 3 275

L-Hing, C: and .Brady, S .D. (1968) Proc. 23rd Industr. i4aste Conference, Purdue Univ., p. 1156

1"9theson,- b.8. dnd Taf t, H.M. (1964) J. ~con.~ntomol. 2, 325

Ueda, K., Baki, H. and Nishimura, H. (1971) Proc. 16th Int. Congress Occup. Health, Tokyo, p. 557

IElls, R.E. (1959) Proc. UW1 Lndustr. \Jaste Conference, Purdue ~ n i v . , p.340

Risebrough, 8.J. et a l . (1969) Science, e, 1233--

Robinson, '.J. (197l) Chemistry i n Britain, 7, 472-475

Smart, ii.A. (1968) aesidue Rev. 23, 1-36

Storherr, R9., l?urray, E.J., Klein, Land 9osenberz, L.A. (1967), ~.kssoc. Off lc . Anal. Chemists, 50 - ( 3 ) 605

Study of Cri t ical Environmental Problems (1970) ITanfs impact on the glohal environment, Boston, iTassaci~ussets Ins t i tu te of TC?chno1osq*

Study Group cm Eiercury Hazards (1971) Environmental Research, 4.1 - Tabor, B.C. (1966) Trans B.Y. Acad. Sci. Ser. 2, ~ ( 5 1 , 569

Technical Committee on the :)i.sposal of Toxic Solid ?.Tastes (1970) Disposal of Solfd Toxic 'dastes, London, 3.30 .

Thomson, J. and Abbot, D .C. (1967) Pesticide Residues, Royal Ins t i tu te of Chemistry Lecture Series, >To. 3, London R I C

~~/S@I.HLTH. w'z .w~/lh &Inex I. Page iv

US Department of A.piculture (1966), Monitnring agrLcultural pesticide residues, USDA Public, MS, Bl-U, :,Jashington D.C.

US Department of Health, Education and Yslfare (1969) 2 - Secretaryfs Conmission on Pesticides and the i r Relations i p to Environ- mental Kealth,Part I and 11, dashington 3.C., iiS Government i'rinting Office

US Environmental' Trotectibn Agency (1971) Proposed Xationd M s s i o n Standzlds for Hazardous Air Pollutants - Asbestos, Bervllium,24ercury, Offdce of.&* Prolpanes; Research T r b g l e park, 1q.C.

Postal J. (1971) in Tiercury i n the Environment (:?riberg, L. and J o s b l , 8. ~ d s . ) Environmentel Protectton Ayency. Resoar ch Triangle Park, X.C.

'rJamfick, S.L., rmt i re , R.F. and,%;aufin, B.R. (1956) J . Amer.?~Jater Xorks A 2 . ,B, 601

Veam+, L. e t a 1 (1965), US. h b l i c Health 3ept. -:?ash, 80, h81

~,~eswd, G. (1966) Acta Chem.. Scand. 2 0 , ,2131 - See dl60 ibid.21, 179% 22,2277

Wood, J.H. (1971) ifdvances i n Environmental Science and .Technols~, 2, 39-56 , . .

Uorld Health Organization (1971) International, Stan3.ards for Drink inq Uater, 3rd.ed., Geneva; (1973) Coiltrol bf 'esticides, A suxvey of Legislation, Geneva

30 (10) 26 Zahidov, L.Z. and ntabaev, 3.G. (1965) i i g . San., - Zweig, G. (1970) in assays i n Toxicology, 1, 156, $rank. R. Blood, ed.. hcad.fess

Zweig, G. and Breide~lbach, R. .. (1961), Abstr. &Oth ileeting ~rne?:. ~hem.~oc,, Chicago, I l l inois , p. 2017

BHG lindane [gamma isomer] md

1,2,3,4,5,G-Hexachlm- HCCL cI.:CI cyclohexane CIICI

toxaphene Synthesized by chlorination of camp?lr-.ne to chlorine :o:'r:cnt of 67-69%.

Common S;.tne f:hc~uiv~l Nsmc S(r\lrtrt:r! Futn~ulr

end rin 1,Z,3.4,10,! 0-hcxscbloro-5.7- epoxy-;i,4.la,5,Li,:J,ir.8a-octn- O( ~ f t l,ydro-~.4-ertdo-endo-s,~-tli- mclhancnapht halc?ic

heptachlor 1.6,5,6.7,8.8-hkpt~ch~oro-3a,4.7, 9a-tetrahydro-3,7-enbo~icth- If C cii 1 G C ~ anoindene I\ / \c/'

C H ci Cl

DDT 2.8-bis (p-chlorophe2yl)-I,>,?-

.'FM/SP~.HL,TH.MZ. ~&P,/14 . . , . Annex I1 m e iii

t,%O S diadnon \ I! N

0.0-Dir.th~.lU-[~-isoprcpy! P-0.- C! ~c-cH~cs-?;, , 11 ! -i-mcth.;1-8-pyrimidyt) - G.H@ ktC,

pf10sp11orcdiiontc G

malathion C&O\ [ 0.U-dfmeihyt S-(1 ,z-di- / P-S- p0.~. czrheihoxyelhyl) phosphoro- diihioatc ch'$o

CHICOOC?W~

methrl parathion 0.0-Dimethyl-0-p-nitraphe~yl phospharati~ioa;~ / CK .1

Contnon Name Chmrticr! Narnu $tr~;c!tara! T : ~ ~ ~ ~ , : I I ~ L !

paraihian , O,O-Ui;:thjf-3-p-tiiIral~bc~iyl pIkvspiiG?olfiio:IfC

0 4-dimethyjamino-3,5-sylyl N-methylc;~rbarnn:e CfI:-t:- -C-Cl

CI I.;

w / Q g n . l i W H . F U z . ~ / r 4 Annex.. 11- mgs

I1J:'REICIDCS

2,4 -D 2,4-dichIoroph-noxyi!r:e:ic acid

a.e,s-T 2,4,5-f?if:bfornrjhenor:y:.r:n;ic

acid Ci