Predicted bioconcentration factors and soil sorption coefficients of pesticides and other chemicals

ECOTOXICOLOGY

AND

ENVIRONMENTAL

SAFETY

4, 26-38 (1980)

Predicted Bioconcentration Factors and Soil Sorption Coefficients of Pesticides and Other Chemicals1 EUGENE E. KENAGA Health

and Environmental

Sciences,

The Dow

Received

May

Chemical

Company,

Midland,

Michigan

15, 1979

Equations were used to calculate soil sorption coefficients (K,,) and bioconcentration factors (BCF) for 358 compounds, mostly pesticides, from known water solubility values. Bioconcentration factor (BCF) values were also calculated from K,, values. Comparisons were made between calculated and actual values where possible. The highest experimental BCF values were associated with persistent chemicals having water solubilities below 0.1 ppm. With some exceptions, such as certain ionic compounds, the highest K,, values were also associated with low water solubility. Calculated values for BCF or K, in excess of 1000 should be experimentally confirmed in order to be certain of their environmental significance. Of the values calculated from water solubility, 10% of the BCF values were over 1000 and 30% of the K,, values were over 1000. BCF and K,, values are simple to calculate from water solubility and are useful for estimation of partitioning in soil, and in animal tissues for contributing to early assessment of potential hazard. Low water solubility is not a good indicator for differentiating between insecticides, fungicides, and herbicides.

INTRODUCTION Kenaga and Goring (1978) studied experimental data from 170 chemicals, mostly pesticides, for relationships between their water solubilities (WS), soil sorption coefficients (based on soil organic carbon content (K,), octanol-water partition coefficient (KOW), and bioconcentration factor (BCF) values in animal organisms. Binary regression equations between the logarithms of these parameters gave correlation coefficients which were all significant below the 1% level. Using these equations, measured values for any of the four parameters could be used to estimate values for the unmeasured parameters. Most compounds showed good agreement. In the few instances where there was large variation of actual from predicted values, the variation could be explained by the type of methodology used to make the measurements, the ionic nature of some of the chemicals, the characteristics of the soils and fish, and the environmental conditions employed in the studies. The data were useful for early assessment of the potential for bioconcentration and mobility of chemicals in the environment and the possibility of hazard. Previous equations prepared for translating WS to BCF values were published by Chiou et al. (1977) and Lu and Metcalf (1975). The equation prepared for translating K, to BCF values was presented by Kenaga and Goring (1978). This study uses certain equations developed by Kenaga and Goring to predict soil sorption coefficients and bioconcentration factors for compounds where these values are not known but water solubility is known. r Paper presented at the International Symposium “Testing of Chemical Substances for Ecotoxicological Evaluation,” May 15-17, 1979, Munich-Neuherberg. 0147-6513/80/010026-13$02.00/O Copyright 0 1980 by Academic Press, Inc. AU rights of reproduction in any form reserved.

26

BIOCONCENTRATION

FACTORS AND SOIL SORPTION

OF PESTICIDES

27

METHODS The equations used in this study, taken from Kenaga and Goring (1978), are shown below. (1) Log BCF* = 2.791 - 0.564 (log WS) ? 1.99 orders of magnitude (OM) (95% confidence) from the calculated value. WS units are parts per million as shown in the tables. (2) Log BCF* = - 1.579 + 1.119 (log K,) & 1.95 OM (95% confidence limit) from the calculated value. *BCF values are calculated from equations for flowing water systems (f) rather than from the terrestrial-aquatic systems (t) shown by Kenaga and Goring (1978). BCF(f) values average almost one order of magnitude higher than BCF(t) values. The equation used for prediction of soil sorption coefficient values was as follows: (3) log Kx = 3.64 - 0.55 (log WS) t 1.23 OM (95% confidence limits) from the calculated value. Water solubility data were obtained from the summaries of Kenaga and Goring (1978) and the Pesticide Manual of Martin and Worthing (1977). Soil sorption data were obtained from the summary of Kenaga and Goring (1978). Two predictive values for BCF (derived from WS and K,, equations) are given for comparative purposes. The use of these equations may be invalid for compounds that do not penetrate well through tissues, are rapidly degraded or otherwise rapidly lost from soil or water, are rapidly metabolized by living organisms, or are ionic and bound strongly to soil by electrostatic interaction. High K,, values unrelated to soil organic matter content occur with compounds that are strong cations, or anions that react strongly with soil mineral constituents such as iron and aluminum. Exceptions and limitations in the use of these equations for predictive purposes are discussed by Kenaga and Goring (1980). RESULTS

AND DISCUSSION

The predicted values of BCF and K,, from water solubilities Goring (1978) are given in Table 1. The experimental values also given, when available. Organic pesticides, which have definitive water solubilities listed by Martin and Worthing Table 2 along with predicted BCF and K,, values.

listed by Kenaga and for BCF and K,, are common names and (1977), are shown in

Prediction of Soil Sorption Coefficients

When the 100 experimental values of K,, in Table 1 were compared with K,, values calculated from WS, 87% fell within one order of magnitude and 95% within two orders (see Table 3). Compounds having a K,, value of around 1000 are quite tightly bound to organic matter in soil and are considered immobile. Those below 100 are moderately to highly mobile. The K, value is useful as an indicator of the potential leachability of compounds through soil or their potential binding on stream sediments. K,, also indicates whether compounds applied to land are more likely to enter water by runoff in solution or on eroded solids.

28

EUGENEE.KENAGA TABLE1 WATER

SOLUBILITY, SOIL ADSORPTION COEFFICIENT, FACTOR DATA: EXPERIMENTAL AND

Chemical (use) Acephate (I) Alachlor (H) Aldicarb (I) Aldrin (I) Ametryn (H) Aniline Anthracene Asulam (H) Atrazine (H) Benelin (H) Bentazon (H) Benzene Bifenox (H) Biphenyl Bromacil (H) Bromobenzene Butralin (H) x-set-Butyl-4-chlorodiphenyloxide Captan (F) Carbaryl (I) Carbofuran (I) Carbon tetrachloride (IF) Carbophenothion (I) Chloramben (H) Chloramben, methyl ester (H) Chlorbromuron (H) Chlordane (I) Chlorobenzene 4-Chlorobiphenyl 4-Chlorodiphenyloxide Chloroneb (F) 6-Chloropicolinic acid Chloroxuron (H) Chlorpropham (H) Chlorpyrifos (I) Chlorpyrifos-methyl (I) Chlorthiamid (H) Crotoxyphos (I) Crufomate (I) Cyanazine (H) Cycloate (H) 2,4-D acid (H)

Water solubility” twm) 650,000 242 7,800 0.013 185 36,600 0.073 5,000 33
AND BIOCONCENTRATION CALCULATED

Soil adsorption coefficient K,,” 190 410 392 26,000 300 149 10,700 0 83 72 150 8,200

230 45,400 21 507 460

1,200 9 3,200 590 13,600 3,300 107 170 200 345 20

&cb 3 210 32 47,600 250 13 18,400 40 640 >4,400 140 71 7,800 1,400 1,350 150 4,400 13,000 >6,400 570 160 110 7,900 120 310 510 21,300 150 3,300 2,400 1,400 50 2,500 370 8,500 2,000 100 100 240 260 380 100

Bioconcentration factor Bioconpredicted fromb centration factor n WS f&c 0.3 28 4 7,160 33 ;,700 5 86 ~620 19 9 1,120 198 185 20

9 22 21 2,300 16 7 850 0 3 340 3 630

1,870 >910 77 21 14 1,140 15 41 68 3,140 20 465 330 190 6.3 350 50 1,220 280 13 13 31 34 50 13

298 12 18 4,300 0.8 28 25 11,400 12 590 736 71 0.3 220 33 1,100 230 5 8 10 18 0.8

450

BIOCONCENTRATION

FACTORS

TABLE

Chemical (use) DBCP (IF) DDD 0, DDE DDT (I) DSMA (H) Dalapon (H) Dialifor (I) Di-allate (H) Diamidaphos (I) Diazinon (I) Dicamba (H) Dichlobenil (H) Dichlofenthion (I) p-Dichlorobenzene 4,4’-Dichlorobiphenyl 3,6-Dichloropicolinic acid cis-I ,3-Dichloropropene (IF) trans-1,3-Dichloropropene(IF) Dichlorvos (I) - Dieldrin (I) Diethylaniline Diflubenzuron (H) Dimethoate (I) Dinitramine (H) Dinoseb (HI) Diphenyloxide Dipropetryn (H) Disulfoton (I) Diuron (H) x-Dodeca-x-chlorodiphenyloxide EPTC (H) Endothall (H) Endrin (I) Ethion (I) Ethylene dibromide (IF) Di-2-ethylhexyl-phthalate Fenitrothion (I) Fenuron (H) Fluchloralin Fluometuron (H) Formetanate (I) Glyphosate (H) Heptachlor (I) Hexachlorobenzene 2,2’,4,4’,5,5’-hexachlorobiphenyl

Water solubility” Cwm) 1,230 0.005 0.010 0.0017 254,000 502,000 0.18 14 50,000 40 4,500 18 0.245 79 0.062 1,000 2,700 2,800 10,000 0.022 670 0.2 25,000 1.1 50 21 16 25 42 0.052 365 100,000 0.024 2 3,370 0.6 30 3,850
AND

SOIL

SORPTION

29

OF PESTICIDES

1-Continued Soil adsorption coefficient KOC”

Kxb

Bioconcentration factor Bioconpredicted fromh centration factor n WS Kc

87 11 6 80,500 12,270 55,000 8,300 238,000 146,000 22,500 27,000 770 5 0.55 45 3 0.36 11,000 1,625 1,000 140 120 1,900 32 11 1 570 77 43 5 0.4 0.01 235 890 120 12 1,370 9,500 390 53 20,000 2,970 2 98 13 0.06 23 57 7 26 55 7 28 3 35,600 5,300 120 16 6,790 10,600 1,530 510 17 2 4,000 4,100 586 280 124 510 68 6 820 110 1,170 950 130 71 1,780 740 100 110 400 560 75 22 129

240 15,400 44 27 3,600 175 2,640 3,914

22,200 170 7.8 34,000 3,000 50 5,800 670 47 :>4,400 370 :>98 25 30,000 28,000

3,275 22 1.0 5,060 418 6 820 91 6 >618 47 >13 3 4,465 4,090

61,600

1 35

215 215

5,800

196

12 4,050 1,300 2 380 1 250 9 180 280

17,400 8,600

1,200,OOO195,000 30,400 170,000 -46,000

30

Chemical (use) x-Hexyl-x-chlorodiphenvloxide Ipazine (H) Isocil Isopropalin (H) Kepone (I) Leptophos (I) Lindane (I) Linuron (H) Malathion (I) Metalkamate Methazole (H) Methomyl (I) Methoxychlor (I) 2-Methoxy-3,5,6-trichloropyridine Methyl isothiocyanate Methyl parathion (I) 9-Methylanthracene 2-Methylnaphthalene Metobromuron (H) Metribuzin (H) Mexacarbate (I) Mirex (I) Monolinuron (H) Monuron (H) Naphthalene Napropamide (H) Neburon (H) Nitralin (H) Nitrapyrin Nitrobenzene Norflurazon (H) Oxadiazon (H) Paraquat (H) Parathion (I) Pebulate (H) Pentachlorobenzene 2,2’,4,5,5’-Pentachlorobiphenyl (Aroclor 1254) Pentachlorophenol (IF) Phenanthrene Phenol Phorate (I) Phosalone (I) Phosmet (I) Phthalic anhydride Picloram (H)

EUGENE

E. KENAGA

TABLE

1-Continued

Water solubility” (mm) 0.076 40 2,150 0.11 3 2.4 0.150 75 145 <50 1.5 10,000 0.003

Soil adsorption coefficient KOC”

Koch

Bioconcentration factor Bioconpredicted fromb centration factor” WS K,,

18,000 570 64 14,700 2,400 2,700 12,400 410 280 >510 3,500 28 107,000

2,640 77 8 2,150 333 377 1,800 54 37 >68 490 3 16,360

20.9 920 7,600 6 57 9,800 0.261 65,000 25.4 8,500 330 60 1,220 95 120 0.6 5,800 580 200 230 100 31.7 1,300 73 680 4.8 2,300 0.6 960 40 420 1,780 28 1,914 0.7 3,241 1,ooo,ooo 15,473 24 4,800 60 630 0.135

820 32 470 9,100 740 180 88 310 1,200 130 220 650 410 1,800 5,800 570 71 700 5,300 2 760 460 13,000

111 4 63 1,320 100 23 11 42 820 17 29 88 55 255 800 77 9 94 756 0.3 100 61 1,900

120 220 1,600 350 35 280

0.01 14.0 1.29 82,000 50 10 25 6,200 430

55,000 l,ooO 3,800 9 510 1,200 740 36 160

8,300 140 535

4,000 53 zo@J

68 167 100 5 20

220

1,660 130 75,250 9,300 911 820 2,620 160 80,000

42,500 900 23,000 27 3,200

17

18,000

110 6 7,500 730 54 48 180 8 8,100

8,400 750 325

185

55 0.2 770 6,400 660 3 4 10 5 80 39 150 57 23

0.6

-5,000 45,600 16

BIOCONCENTRATION

FACTORS

TABLE

Chemical

(use)

Profluralin (H) Prometon (H) Prometryn (H) Pronamide Propachlor (H) Propazine (H) Propham (H) Propoxur (I) Pyrazon (H) Pyrene Pyroxychlor Ronnel (I) Silvex (fenoprop) (H) Simazine (H) 2,4,5-T (H) Tebuthiuron (H) Terbacil (H) Terbufos (I) Terbutryne (H) Tetracene I ,2,4,5-Tetrachlorobenzene 2,2’,4,4’- and 2,2’,-5,5’-tetrachlorobiphenyl (Aroclor 1254) Tetrachloroethylene Thiabendazole (F) Thionazin (l) Toxaphene (I) Tri-allate (H) Trichlorfon (I) 1,2,4-Trichlorobenzene 2,4,4’- and 2,2’,5-trichlorobiphenyl (Aroclor 1016, 1242) 3,5,6-Trichloro-2-pyridinol Triclopyr (H) Triclopyr, butoxyethyl ester (H) Triclopyr, triethylamine salt (H) Trietazine (H) Trifluralin (H) Urea

Water solubility” @pm) 0.1 750 48 15 580 8.6 250 2,000 400 0.135 11.3 6.0 140 3.5 238 2,300 710 12 25 0.0005 6

AND

SOIL

SORPTION

1-Continueci Bioconcentration factor predicted fromb

Soil adsorption coefficient KOC”

WS 2,260 15 70 134 17 184 27 9 21 1,910 157 225 38 300 28 8 15 152 100 45,000 225

1,720

41,000 240 >510 100 7,200

2,220

Loo0 6 670

6,150 31 68 13 1,040 282 0.7 91

17,000 220 160

2,480 30 20

23

780

105

2,100,OOo 20 600 0.6 13,700 1 ,OOo,oOO 14

1.5 840 5,800 2

0.2 114 824 0.3

0.085 220 430

8,600 350 810 200 265 160 51

Lb 15,500 110 520 990 130 1,300 210 67 160 13,000 1,200 1,600 290 2,200 220 61 120 1,100 740 290,000 1,600

0.017 200 <50 903 0.40 4 154,000 30

31

OF PESTICIDES

120 84,000 3,000 2,600 135 53 620 51 700 650,000

130 27

a Experimental values (as summarized by Kenaga and Goring, 1978). ’ Calculated values (using equations of Kenaga and Goring, 1978). c (F) Fungicide; (H) herbicide; (I) insecticide; (IF) insecticide fumigant.

K,,

Bioconcentration factor a

670 19 47 10 14 8 2 6 8,500 210 170 6 2 35 2

1

40 84,000 4,500 72,950 39 110 26,400 150 491 6 1

34 1,100 0.5

48,980 3

4,570

32

EUGENE

E. KENAGA TABLE

2

SOIL SORPTION COEFFICIENTS AND BIOCONCENTRATION FACTORS CALCULATED FROM WATER SOLUBILITY

Pesticide Acrolein (H)b Acrylonitrile (IF) Allidochlor (H) Aminotriazole Ancymidol (PR) Antu (Ro) Aziprotryne (H) Barban (H) Benazolin (H) Bendiocarb (I) Benodanil (F) Benomyl (F) Bensulide (F) Benzyloprop-ethyl (H) Benzthiazuron (H) Bromophos (I) Bromophos-ethyl (I) Bromoxynil (H) Bupiramate (F) Butacarb (I) Butachlor (H) Buturon (H) Butylate (H) Cacodylic acid (H) Camphechlor (I) Captafol (F) Carbendazine (F) Carbetamide (H) Carbon disulftde (IF) Carboxin (F) Chloranil (F) Chlorbufam (H) Chlordimeform (I) Chlorfenac (H) Chlorfenprop-methyl (H) Chlorfenvinphos (I) Chlorflurecol-methyl (PR) Chlormephos (I) Chloroneb (F) Chlorpicrin (IF) Chlorothalonil (F) Chloroxuron (H) Chlorpropham (H) Chlorquinox (F) Chlorthal-dimethyl (H)

Water solubility” @pm) 200,000 75,000 19,700 280 650 600 55 11 600 40 20 3.8 25 20 12 40 2 130 22 15 20 30 45 2,000 3 1.4 5.8 3.5 2,200 170 250 540 250 200 40 145 18 60 8 2,270 0.6 3.7 89 1 0.5

Bioconcentration factorr 5 9 19 200 120 130 480 1,160 130 570 840 2,100 740 840 1,100 570 3,000 300 800 980 840 670 540 67 2,400 3,600 1,700 2,200 63 260 210 140 210 240 570 280 890 460 1,400

62 5,800 2,100 370 4.400 6,400

0.6 1 2 26 16 17 64 160 17 77 114 290 100 114 152 77 418 40 106 134 114 90 72 9 330 510 230 300 8 34 27 18 28 31 77 37 121 61 190 8 820 295 49 620 910

BIOCONCENTRATION

FACTORS

TABLE

Pesticide Chlortoluron (H) Cyanazine (H) Cyanofenphos(I) Cyanophos (I) Cyanthoate (I) Cycloheximide (H) Cycluron (H) Daminozide (PR) 2,4-DB (H) Demephion(I) Demeton (I) Demeton-S-methyl (I) Desmedipham(H) Desmetryne (H) Dibutyl phthalate (IR) Dichlone (F) Dichlorophen (F) 1,3-Dichloropropene Dichlorprop (H) Difenoxuron (H) Dimethanetryn (H) Dimethirimol (F) Dimethyl phthalate (IR) Dinosebacetate (H) Dioxacarb (I) Diphenamid (H) Ditalimfos (F) DNOC (I) DSMA (H) Ethirimol (F) Ethoate-methyl (I) Ethofumesate (H) Ethoprophos (I) Ethylene dichloride (IF) Fenaminosulf (F) Fenamiphos(I) Fenarimol (F) Fenfuram (F) Fenthion (1) Fentin acetate (F) Ferbam (F) Flamprop (H) Fluorodifen (H) Fluotrimazole (F) Flurecol-butyl (PR) Folpet (F) Formothion (I) Glyphosine (PR)

AND

SOIL

SORPTION

33

OF PESTICIDES

2-Continued

Water solubility” (pw-0 70 171 0.6 46 70 21,000 1,100 100,000 46 300 60 3,300 580 -400 0.1 30 1,000 350 20 50 1,200 4,300 2,200 6,000 260 133 130 254,000 200 8,500 110 750 4,300 20,000 700 13.7 100 55 28 130 18 :.001 36 2,600 248,000

KO,’ 420 260 5,800 530 420 18 93 8 530 190 460 51 1.500 130 160 15,500 670 98 170 840 510 88 44 63 36 210 300 300 240 30 330 110 43 19 119 1,030 350 480 700 300 890 3,000 195,000 600 4,400 58 5

Bioconcentration factor’ 56 34 820 71 56 2 12 0.9 71 25 61 6 200 17 -21 2,260 91 13 23 II4 68 11 6 8 5 27 39 40 0.6 31 4 44 15 6 2 15 140 46 64 94 40 120 420 30,400 82 618 7 0.6

34

EUGENE E. KENAGA TABLE 2-Continued

Pesticide Halacrinate (F) Heptenophos(I) Ioxynil (H) Ioxynil, sodiumsalt (I-I) Isazophos (I) Isocarbamid (H) Isofenphos (I) Isonoruron (H) Isoproturon (I) Karbutilate (H) Kasugamycin (F) Lenacil (H) Maleic hydrazide (H) MCPA (H) MCPB (H) Mecoprop (H) Mecoprop, potassiumsalt (H) Mecoprop, diethanolaminesalt (H) Mefluidide (H) Menazon (I) Metaldehyde (M) Metamitron (H) Metham-sodium(FH) Methidathion (I) Methoprotryne (H) Metolachlor (H) Metoxuron (H) Metribuzin (H) Molinate (H) MSMA (H) Napthalam (H) Neburon (H) Niclosamide(M) Niclosamide,ethanolaminesalt (M) Nitrofen (H) Norbromide (M) Norflurazon (H) Oryzalin (H) Oxamyl (I) Oxycarboxin (F) Pentanochlor (H) Perlluidone (H) Permethrin (I) Phenmedipham(H) Phenobenzuron(H) Phenothrin (I) Phenthoate (I) Phenylmercury acetate (F) Phenylmercury, dimethyl (F) dithiocarbamate 2-Phenylphenol(F)

Water solubilityU (mm)

Bioconcentration factorr

6 2,500 50 140,000 150 1,300 23,800 220 60 325 125,000 6 6,000 825 44 620 795,000 580,000 180 240 200 1,800 722,000 240 320 530 678 1,200 800 570,000 300,000 48 5 230 1 60 28 2.4 280,000 1,000 8 60 0.2 3 16 2 200 4,370

1,630 60 510 6 280 85 17 220 460 180 7 1,630 40 110 540 130 2 3 250 210 240 71 2.6 210 180 140 121 88 110 3 4 520 1,800 220 4,400 460 700 2,700 4 98 1,400 460 10,600 2,400 950 3,000 240 43

A63 0:4 33 28 31 9 0.3 28 24 18 16 11 14 0.4 0.5 70 250 29 618 61 94 377 0.5 13 190 61 1,530 330 130 420 31 5

6 700

1,630 120

225 15

225 7 68 0.8 37 11 2 30 61 24 0.8 225 5 14 73

BIOCONCENTRATION

FACTORS TABLE

Pesticide 2-Phenylphenol, sodiumsalt (F) Phoxim (I) Pindone (I) Piperophos(H) Pirimicarb (I) Pirimiphos methyl (I) Potassiumcyanide (H) Profenofos (I) Promecarb (I) Propanil (H) Propetamphos(I) Propyzamide (H) Prothiocarb (F) Prothoate (I) Pyracarbolid (F) Pyrazophos (F) Quinacetol sulphate(F) Quinalphos (I) Quinonamid (H) Rotenone (I) Sabadilla(I) Secbumeton(H) Siduron (H) Simetryne (H) Strychnine sulphate (R) Sulfallate (H) Sulfotepp (I) 2,3,6-TBA (H) Terbumeton (H) Terbuthylazine (H) Tetrachlorvinphos (I) Thiazafluron (H) Thiometon (I) Thiram (F) Tolylfluanid (F) Tetradimefon (F) Triazaphos (I) Trichloronate (I) Trichlorphon (I) Tricyclazole (F) Trifenmorph (M) Vamidothion (I) Vernolate (H) Vinclozolin (F) Zineb (F) Ziram (F)

AND

SOIL

SORPTION

35

OF PESTICIDES

2-Continued

Water solubility” @pm) 1,100,000 7 18 25 2,700 5 720,000 20 92 225 110

15 890,000 2,500 600 4.2 10,000 22 3 ::5 620 18 450 30,000 92 25 7,700 130 8.5 11 2,100 200 30 4,000 260 39 50 154,000 1,600 0.02 4,000,000 107 1,000 10 65

a From Martin and Worthing (1977). D (F) Fungicide; (H) herbicide; (I) insecticide; (IF) insecticide molluscacide; (PR) plant growth regulator; (R) rodenticide. r Calculated from water solubility by regression equations.

Rioconcentration factorC

Kc,,’ 2 1,500 890 740 57 1,800 3 840 360 220 330 980

0.2 206 121 100 7 250 0.3 114 46 29 44 134 0.3 7 17 275 3 108 330 134 18 16 121 20 2 48 100 4 40 185 160 8 31 91 6 27 78 68 0.7 10 5,600 O.f2 44 13 169 59

f9 129 1,980 28 800 2,400 980 140 130 890 150 15 360 740 32 300 1,350 1,170 65 240 670 46 205 580 510 6 75 37,500 I 330 98 1,230 440 fumigant;

(IR)

insect

repellent;

(M)

EUGENE E. KENAGA

36

TABLE 3 COMPARISON

OF CALCULATED

AND

EXPERIMENTAL

VALUES

OF

K,

AND

BCF”

Values compared Orders of magnitude difference between values

K,, experimental

vs calculated No. (%)

BCF experimental vs BCF (WS or K,,) calculated No. (%)

51

96 (87) 10 (9)

45 (87) 7 (13)

2 (2) 2 (2)

0 (0) 0 (0)

>l-2 >2-3 >3

BCF (WS) calculated vs BCF (K,,) calculated No. (%) 87 (78) 20 (18) 3 (3)

1 (1)

n From Table 1.

If the compound is applied to land and has a high K, value the main route to water will probably be through soil particles washed down because of heavy precipitation or water from melting snow or ice. If the compound has a very low K,, then the chemical is apt to be picked up in solution by water percolating over or through the treated area. Steep slopes will increase water runoff and pick up of chemicals in both instances. Chemicals with high K,, values will be immobile when incorporated in soil. Four pesticides showed a substantial difference between experimental and calculated K,, values, i.e., aldrin, DSMA (disodium methylarsonate), glyphosate (N-phosphonomethyl glycine), and paraquat (l,l-dimethyl-4,4’-bipyridylinium ion). The aldrin K,, value is probably incorrect based on its physical properties and should be rechecked experimentally. The K,, values of the other three chemicals appear to be related primarily to the mineral properties of soil rather than to organic matter. The low K,, values predicted for glyphosine and MSMA in Table 2 are probably as inaccurate as those for DSMA and glyphosate, respectively for the reasons previously stated. It would appear that these exceptions relating to ionic materials should be examined more closely for sorption relationships not explained by soil organic matter. Prediction of Bioconcentration

Factors

Bioconcentration factor data contained in Table 1 include both predicted and experimental values. When the 37 experimental values of BCF were compared with BCF values calculated from WS or K,, equations, 87% fell within one order of magnitude and 100% within two orders. When 111 BCF values were calculated from K,, values, 80% fell within one order of magnitude and 95% within two orders of those calculated from WS equations (see Table 3). BCF values which are unexpectedly low based on the equations are probably due to rapid degradability of the chemical. BCF values that are unexpectedly high may be based on poor water solubility or soil adsorption data. Compounds in Table 1 having a BCF of over 1000 are those which from experience are most likely to need -further evaluation for hazard assessment. Inspection of the data in Table 1 shows 16 of the 37 experimental values exceed a BCF value of 1000.

BIOCONCENTRATION

FACTORS

AND

SOIL

SORPTION

37

OF PESTICIDES

Another parameter which circumscribes BCF potential is water solubility. Of the 16 compounds with experimental BCF values over 1000 all but 1 have water solubilities of 0.1 ppm or less. BCF values over 1000 calculated from WS equations for the 358 compounds from Tables 1 and 2 represent 10% of the total. K,, values over 1000 calculated from WS equations for the same 358 compounds represent 30% of the total. Considering the lack of uniformity of testing methods for determining low water solubility and experimental BCF values, the indicators for potentially significant bioconcentration factors are excellent. The compounds in Tables 1 and 2 were classified by groups as insecticides, herbicides, fungicides, and other chemicals to see whether water solubility was a function of these biological activities. Compounds having water solubilities of less than 1 ppm among the above groups represent 17, 9,4, and 17% of the respective groups (See Table 4). This relatively uniform proportion of compounds in these low water solubility groups does not point to generic biological activity as a good indicator of BCF. Bioconcentration factors vary as much as one to two orders of magnitude between species and life stages probably related in part to differences in fat content and metabolism even with one compound (Kenaga and Goring, 1978). Thus, a given BCF value should not be used as a precise representation of bioconcentration under a variety of conditions. Nevertheless, these data suggest that compounds having predicted BCF values of 100 or less probably do not merit experimental confirmation. Calculated values from water solubility are good enough. For calculated BCF values of higher magnitude, those chemicals that are readily metabolized or degraded should have reduced priority since it is unlikely that the actual BCF value will be higher than the calculated value. CONCLUSIONS Equations for predicting BCF and K,, values developed from experimental values were used to calculate a wide range of BCF and iu,, values of chemicals from their water solubilities. About 95%~of the values calculated were within two orders TABLE DISTRIBUTION

Water

OF CHEMICALS

Insecticide

4

BY USE

AND

WATER

Herbicide

SOLLJBILITY”

Fungicide

Other chemicals

solubility (w-4

No.

O.OOl-CO.01 O.Ol-CO.1 O.l-Cl l-C10 10-c 100 loo-
3 6 8 12 28 20 20

3 6 8 12 29 21 21

0 0 9 21 39 43 34

0 0 6 14 27 30 23

1 0 3 10 10 9 8

3 0 7 24 24 22 20

2 9 6 4 9 4 I1

4 20 13 9 20 9 25

Total compounds

97

100

146

100

41

100

45

100

n From

Tables

1 and 2.

Percentage

No.

Percentage

No.

Percentage

No.

Percentage

38

EUGENE

E. KENAGA

of magnitude of the actual values. BCF and K,, values over 1000 appear to be associated with chemicals having low water solubility (co.1 ppm). The type of biological activity (insecticide, fungicide, and herbicide) does not appear to be related specifically to the BCF and K,, values. ACKNOWLEDGMENTS The author wishes to thank Cleve Goring, Colin Park, Robert Moolenaar, Kenneth Burgess, and Robert Morgan of The Dow Chemical Company for their help in critically reviewing this paper.

REFERENCES CHIOU, C. T., AND FREED, V. H. (1977). Partition coefficient and bioconcentration of selected organic chemicals. 11(5), 475-478. Lu, P., AND METCALF, R. L. (1975). Environmental fate and biodegradability of benzene derivatives as studied in a model aquatic ecosystem. Environ. Health Perspecf. 10, 269-84. KENAGA, E. E., AND GORING, C. A. I. (1980). Relationship Between Water Solubility, Soil Sorption, OctanolWafer Partitioning, and Bioconcentration qf Chemicals in Biota. In Aquatic Toxicology ASTM STP 707, (J. C. Eaton, P. R. Parrish, and A. C. Hendricks, Eds.), American Society for Testing and Materials, in press. MARTIN, H., AND WORTHING, C. R. (1977). Pesticide Manual 5th ed. British Crop Protection Council, Worcestershire, England.