carcinogenesis with the insecticide rotenone

Life Sciences, Vol. 32, pp. 809-816 Pergamon Prem Printed in the U.S.A.

~IINIREVIEW

CARCINOGENESIS WITH THE INSECTICIDE ROTENONE

Mario GosElvez

Department of Experimental Biochemistry. Cllnica Puerta de Hierro. National Center of Medical Research. Madrid-35, Spain

Summary

Rotenone is an insecticide which has been used exten-

sively for a long time, and is now widely used in the U.S.A. and other industrialized countries. Rotenone is used mainly as an agricultural insecticide, household garden insecticide and water plant piscicide. Through these uses, rotenone may now be reaching the human male and female in these countries in substancial amounts, carried by fresh or cooked vegetables, con- sumed fish and drinking water. A review of the exist- ing published reports and unpublished official documents dealing with the capacity of rotenone to induce neoplastic, paraneoplastic and preneoplastic lesions

in the rat is presented here. It is strongly suggested that rotenone is carcinogenic to the rat (at doses from 2 to 25 parts per million continuously in food, or from 0.8 to 2.5 mg/kg weight for I to 4 months by oral administration), above all, when the rats receive deficient diets, especially those poor in riboflavin. Rotenone carcinogenesis, among other things, seems to exhibit a peculiar dose respo1~se pattern, which could be explained by its possible hormonal mechanism of ac- tion. Further studies to assess definitively the role of rotenone as a possible environmental carcinogen are proposed as being highly necessary.

Backsround

A comprehensive review of the literature dealing with rotenone has been published by Haley in 1978 (i). The present review concerns itself solely with the carcinogenic effects of rotencne, and reports of related interest. Rotenone is the insecticidal component of the r~ots of the derris, cube, tuba, barbasic and timbo plants, and its insecticidal and piscicidal properties have long been known to native peoples in various parts of the world. La Forge et al. established the chemical structure of rotenone in 1933 (2) as a steroid-like compound, and its total chemical svn- thesis was arrived at in 1965 by ?liyano (3). Rotenone has been known as a ~ow~rfu! inhibitor ,~f ~itoc~or~dria] electron transport since the work of Oberg in 1961 (4). Many other biochemical and pharmacological effects of rotenone are known (i), but its effect:

0024-3205/83/080809-08503.00/0 Copyright (c) 1983 Pergamon Press Ltd.

810 Rotenone Carcinogenesis Vol. 32, No. 8, ]983

as an insecticide and as a piscicide may possibly be related to

its interference with glutamate oxidation in nerve and muscle at very low concentrations, as shown bv Fukami in 1967 (5). Host biochemical and pharmacological effects of rotenone, including the

cvtostatic effects reported by Figueras and <os~Ivez in 1973 (6), could be explained by its effects as a respiratorv inhibitor (i) .

Data on toxicity of rotenone to insects (1,7), fishes (],8), rats (1,9) and humans (I,]0) are available. Lethal doses for different

classes of insects vary from 0.001 to 2.9 milligrams per liter of pond water, and for different classes of fish, from 0.008 to 0.5 milligrams per liter of pond water. The Dhs0 for rats is ]6 mg,/kg i.p and the 10 parts per million feeding level (it could be estimated approximatelv that this level would correspond to 0. ] to

0.8 mg/kg/day) has been considered safe for hnman consumption (i~

20) .

Environmental Aspects

A report on environmental aspects of rotenone, related to carcinogenesis, has recently been published by Cos~ivez and Dfaz

Oil (i]) . Plants containing rotenone have been used a fish poi- sons for many centuries in many countries. Rotenone, as the ac- tive insecticidal principle, was defined by Ceoffrev in ]895 (i2). Dried cube, derris and tuba roots containing rotenone and other

rotenone derivatives called rotenoids (13) have been in use as

contact and stomach insecticides for probably more than 2~0 \,ears. Their first massive use on crops was in ]848 in British Malaya. Fhe first patent was issued in England in 1911. Rotenone-contain-

ing powders have been used since then in many countries of the

world to treat bush and vine crops, citrons, deciduous fruits,

forage crops, mushrooms, asparagus, beans, beets, corn, eggplant, mustard, peas, potatoes, radishes, strawberries, tomatoes and other vegetables. The types of pests controlled include beetles,

weevils, slugs, ,Japanese beetles, fleabeetles, loopers, cabbage worms, mosquitoes{, thrips, fleas, ]ice, flies and many others.

Rotenone-containing powders have been extensively used in many countries of the world to control undesirable fish species and to eradicate them from lakes, streams and water reservoirs. The selective toxicity of rotenone for different species of fishes permits its use in controlling trash fish without affecting game fish, and :its use in fish ponds to kill undesirable fish

species 2-4 weeks before restocking. It is also applied to dogs, cats or cattle to control parasites (]l) . Rotenone undergoes pho-

todecomposition when irradiated by ultraviolet light. The major toxic photodecomposition products aFe rotenolone, rotenonone and

its epoxides (14). Rotenone persists in water for 5-6 days in the spring and 2-3 days in the summer. The rate of detoxifieation, and hence, the toxicity in water applications, is proportional to light energy, alkalinity, temperature, ice cover, pH, w) lume of water and vertical dissipation of the distribution of rotenone. The duration of toxicity in winter may be up to five months (15).

It is very difficult to quantify the world consumption of rotenone as an insecticide and piscicide at different times. At present, there is a massive use of rotenone in super-industrialized countries, especially in the U.S. , Great Britain, Japan, Sweden, Denmark, Finland, Israel, Canada and Norway (]]) . The

Vol. 32, No. 8, 1983 Rotenone Carcinogenesis 811

U.S.A. started to import derris and tube root from the United Kingdom in 1910 (16). A separate classification under "Derris and tuba or tube roots" existed in the records of U.S. imports in 1943 (17). The peak of rotenone-containing products imported mainly from Peru to the U.S.A. was reached in 1950 when 9,846,000 pounds arrived in the U.S.A. during the twelve months of the crop year. The import of rotenone reached a minimum of 548,871 pounds per year in 1972 (18) due to its production in the U.S. The total yearly consumption of rotenone in the U.S.A. is presently estimat-

ed at 15 million pounds (11). Rotenone is commercialized in the U.S.A. for use as an agricultural insecticide, household garden insecticide or piscicide under several names, i.e. rotenone, derris, cube root, ro-ko, extrax, cubor, rotefire, rotessenol, roto- cipe, noxfish, barbasso, haiari, mexide, fish-tox and pro-noxfish. Presently, rotenone is produced in the U.S. by Pentress Drugs, S. B. Penick, F.M.C. Corporation, Worlfolk Chemical Co. and others, and through its use in household gardens, agricultural fields, water reservoirs and water plants, it is estimated that it may be reaching the human in substancial amounts (11).

Studies on Carcinogenesis

A few studies on the subacute toxicity of rotenone-contain-

ing powders (0.6 to 9.6% of rotenone; the composition of the rest of the powder was not expressed) to dogs, cats and rats appeared from 1931 to 1943 (19), and concluded that rotenone, when fed to these animals for 100 to 200 davs, caused growth retardation and fatty degeneration of the liver at levels of 75 ppm and above in the diet. No tumors were encountered in these reports. In 1950, Dr ..... Lehman of the Division of Pharmacology of the U.S. Food and Drug Administration considered safe for human consumption a

level of i0 parts per million of pure rotenone (20). The same author, in 1952, reported that the principal gross effect of chronic rotenone feeding in the rat was growth retardation and increased incidence of hepatic tumors. The principal histo-pathological change encountered were peculiar hepatic cell masses of 0.5 to i cm, which were classified between hyperplasia and tumor. They occurred at feeding levels of from 2 to I0 parts per million pure rotenone in the diet, but not at higher levels (21). An internal report of the U.$. Food and Drug Administration from Dr. E. L. Long to Dr. A. J. Lehman, dated July 31, 1959 (22), reported work performed several years before on the feeding of male and female Osborne-Mendel rats for two years with pure rotenone in the diet, at levels of 2, 5, i0, 25, 50 and i00 parts per million. This report described a retardation of growth which was proportional to the dose, which started to be significant at 50 parts per million in the females and at i00 parts per million in the males. An in- creasing incidence of a great variety of tumors at all rotenone diet levels was observed with respect to the control diet, but control data was considered misleading in the report, due to the occurrence of an intense early infectious mortality in the control animals, which masked the great variety of tumors which usually appear in these rats in old age. The only significant finding, therefore, concluded in this study was, again, an abnormal incidence of hepatic cell tumors (carcinoma, Adenoma and hyperplasic modules), which occurred at the levels of 2, 5 and i0 parts per million, but not at higher levels. Another curious finding, while observing the results of the rotenone-treated series, without car- ing for the control series results, was that the general incidence

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hormones, estrogen and somatomedins, thus pointing to a hormonal mechanism in the tumorogenic effect of rotenone. The obesity ob-

served in many rotenone-treated rats which do not present tumors

(27) may be relevant in relation to these hormonal effects of

rotenone. In 1978, Cos~ivez and Diaz ~il (11) questioned whether

or not rotenone could be a possible environmental carcinogen. In

1976, the U.S. Environmental Protection Agency scheduled a reval-

uation of rotenone's possible hazards to man and the environment

(30),and in June, 1981, the agency published a summary of the results of Freudental et al. in the revaluation project (31). These authors concluded that, under their experimental condi-

tions, rotenone was not carcinogenic to the two strains of rats (Wistar and Sprague-Dawley), nor to hamsters, but noted that mam-

mary ductal or glandular ectasias and cysts were slightly more prevalent in females among rotenone-treated animals than in control groups. Thev also noted that adrenal cortical adenomas in females and fibrosarcomas in males occured in greater numbers in rotenone-treated groups than in the controls.

In our opinion, the study published by these authors was not conclusive, although it was suspicious with regard to an asser-

tion of rotenone as a carcinogen to the rat, because the investigators did not achieve the critical dosage, critical time of treatment and critical time of observation, nor did they use the adequate diet for the rats. Table I shows data from our labora- torv, expressing the incidence of tumors observed macroscopical-

ly, at different times of observation, in rats treated intraperi- toneally or orally and fed with different diets. It is notewor-

thy that tumors are not observed in our 1980 experiments when

using diets supplemented with riboflavin and other vitamins and minerals. Thus, the main difference in tumor incidence between our reports (25,26,27) and the report of Freudental et al. (31)

may be due to the fact that, in our previous experiments, we used deficient diets all throughout, while Freudental et al. used an enriched rat diet.

Discussion

From the above-reviewed studies, it can be deduced that,

over the years, rotenone has shown the ability to induce preneo-

plastic, paraneoplastic and neoplastic lesions in rats in some experiments carried out bv different investigators. In other recent reports of U.S.A. agencies, onlv suspicions, with no conclusive evidence, have been voiced regarding its carcinogenicity. Our studies might perhaps be the most conclusive due to the use of deficient diets, especiallv poor in riboflavin. This fact

would explain the negative data of the U.S.A. studies in recent years as being due to the new fashion in carcinogenesis studies of using super-rich diets which are completely unreal when com- pared to the human situation. We are well-aware of the fact that for a thorough scientific assessment of carcinogenesis it is necessary to standardize variables, such as diet, environmental conditions, etc., but it would appear at first sight that this standardization should be made more realistically, in accordance with the human situation and taking into account the cooperative factors in carcinogenesis that occur unavoidably in human society. In our opinion, it is a pitv that it has been for-

gotten, as the old Cerman and Japanese literature on carcinogene-

TABLE

I

Incidence

of Mammar~

Tumors

Dete~ ted

Macroscopica]ly

in

Female

Rats

Treated

with

~o[enone.

(Influence

of

Diet~

Rat

Strain

and

Hode

of

Administration.)

OO

Total

dose

Total

Total

Total

Total

Number

of

rotenone:

number

of

number

of

number

of

number

of

Diet

Riboflavin

of

Rat

Mode

of

tumors

at

tumors

at

deaths

at

rats

with

(date

of

content

of

rats

strain

administration

12 months

18 months

18 months

obesity

use)

the

diet

Albino

Sanders

40

0

0

6

N.D.

N.D.

inbred

chow

1970

Albino

Sanders

40

inbred

9.]

mg,

i.p

28

34

14

N.D.

chow

1970

N.D.

Sandermus

70

Wistar

0

0

6

0

chow

1974

3.2

mg/Kg

Sandermus

26

Wistar

7.1

mg,

i.p

4

9

7

7

chow

1974

3.2

mz/K ~

Sandermus

43

Wistar

9.1

mg,

i.p

6

15

12

13

chow

1974

3.2

mg/Kg

Sandermus

58

Wistar

9.0

mg,

i.p

9

2]

17

16

chow

1974

3.2

mg/Kg

Sandermus

9

Wistar

9.0

mg,

2

4

4

1

3 o m~/Kg

oral

cavage

chow

1974

"~

UAR.A.03

20

Wistar

0

0

1

0

diet

1980

13 mg/Kg

UAR.A.03

20

Wistar

9.0

mg,

i.p

0

1

4

i

diet

1980

13 mg/Kg

,m

o ©

c'] 2,. o {9

o

N.D. = Not

determined.

Sanders

chow

contained

58%

corn,

4% barlev,

24Z

soybean,

i%

fish

meal,

13%

bran,

]% ash

and

minerals.

Sandermus

chow

contained

18.597.

protein,

3.11%

fat,

4.5%

fiber,

5.98%

ash.

UAR.A.03

diet

contained

15.5%

vegetable

protein,

15.5%

animal

protein,

69%

carbohydrates,

fat

and

cereals,

4% vitamin

complement.

Sanders

and

Sandermus

chows

were

obtained

from

Uni6n

A]i-

menta~-ia

Sanders,

S.A. , Madrid,

Spain,

and

UAR.A.03

rat

diet

was

obtained

from

Panlab,

S.L. , Bar-

celona,

Sp

ain

.

oo

<o

oo


sis pointed out, that deficient diets, especiallv those which

are poor in riboflavin, play a marked role in tumor incidence with certain types of carcinogens. Another factor in the repro- ducibilitv of rotenone carcinogenesis is the critical range of effective oral dosification, namely 2 to 25 parts per million

continuously, or 0.8 to 2.5 milligrams per kilogram of weight for 1 to 4 months. This is the necessary case in order to induce rotenone tumors because the dose response curve for carcinogenic studies has a very characteristic bell-shaped pattern. In our opinion, the bell pattern of the dose response curve ~s not due

to the fact that high doses shorten life span, precluding tumor development because tumor incidence decreases markedly when life

span or growth are not vet affected (32). It is possible that the bell-shaped curve could be related to the hormonal effects

of rotenone (29). Still another ~actor in rotenone carcinogenesis reproducibility is the duration of observation, because rotenone has a long latency period. The use of oils as solvents

in oral cavage experiments may be another factor which plays a role.

We stronglv suggest that rotenone is carcinogenic for the rat after oral administration of critical dosages and the inci-

dence of tumors, as well as the tumor types achievable, depends

on the rat strain, diet and other factors. This effect and the wide environmental role of this insecticide and piscicJde in in-

dustrialized countries strongly suggests that rotenone might be an environmental carcinogen, because it seems to be reaching humans in the U.S.A. in substancial amounts (ii) . However, to as-

sess definitively rotenone as an environmental carcinogen, further studies are needed. Three types of studies could be listed

as highlv necessary: I) Carcinogenesis studies in standardized conditions in several adequate animal species, taking into account at least some of the necessary critical conditions for rotenone carcinogenesis, such as dose, diet, solvent, time of

treatment and time of observation; 2) Human exposure studies by market basket surveys and tap water surveys in manv adequate areas in the U.S.A.; and 3) Epidemiological studies in the U.S.

to indagate what householA garden insecticides were frequently used vests ago bv groups of persons who later suffered from cancer,especially mammarv and hepatic Cancer, with respect to cancer-free groups of the same social and nutritional characteris- tics.

Acknowledgements

The work carried out by the author's laboratory, reported or reviewed in this paper, was supported by several grants from the Spanish National Institute of Health and by grant 5-R0]-CAI6776, awarded by the U.S. National Cancer Institute, D.H.E.W., U.S.A.

References

i. T.J. HALEY, J. Environmen. Pathol. and Toxicol. i 315-337 (1978).

2. F.B. LAFORGE, H.L. HALLER and L.E. SHITH, Chem. Rev. 12 181- 184 (1933).

3. M. MIYANO, J. Am. Chem. Soc. 87 3958-3962 (1965). 4. K.E. OBERC, Exptl. Cell Res. 24 163-]66 (1961).

816 Rotenone Carcinogenesis Vol. 32, No. 8, 1983

5. J. FUKAMI, I. YAMAMOTO and .I.E. CASIDA, Science 155 713-715 (1967) .

6. M.J. FIGUERAS and M. COSALVEZ, Eur. J. Cancer 9 529-531 (1973) .

7. W.D. WATKINS and D.C. TARTER, Proc. W. Va. Acad. Sci. 46 141-143 (]974) .

8. O. ~AUDIN and R. VACHERAT, Bull. Sci. Pharmacol. 45 385-390 (1938) .

9. R. SANTI and E. TOTH, Farmaco. Ed. Sei. 20 270-276 (1965) .

10. J. RACOUCHOT, Arch. Ma. Profes. 2 149-152 (1939) .

if. M. GOSALVEZ and J.J. DIAZ-GIL, Eur. J. Cancer ]4 1403-1404 (1978) .

1 2 . E . G E O F F R E Y , A n n . I n s t . C o l o n . M a r s e i l l e s 2 1-O ( 1 8 9 5 ) . 13. M ONO, Oyo-Kontyu 3 34 (1941) .

14. H.M. CHENG, I. YAMAMOTO and .J.E. CASIDA, J. Agr. Food Chem. 20 850-855 (1972).

15. R. SCHNICK, A Review of the Literature on the Use of Rotenone

in Fisheries, FWS-CR-74-15, File no. PB-235 454/AI, ~]ational

Technical Information Service, U.S. Department of Commerce, Sheffield, Va. (1974) .

16. Foreign Commerce and Navigation of the United States, Bihlio- teca Nacional, Madrid, Spain.

17. Statistical Classification of Imports into the United States,

Schedule A, Census Bureau, U.S. Department of Commerce (1943).

18. Census Bureau Report, FT246, TSUSA, schedules 493-0200 and

493-0400, U.S. Department of Commerce (1964-1972) .

1 9 . W . t I . HANSEN, K . J . DAVIS a n d O . C . FITSHLTC, t l , T o x i c o l o g y a n d A p - p l i e d P h a r m a c o l o g v 7 5 3 5 - 5 4 2 ( 1 ( ) 6 5 ) .

20. A.J. LEHMAN, Assoc• Foo3 and Drug Officials of U.S. Quart.

Bull. 14 82-86 (1950) .

21. A..I. I+EHMAN, Assoc. Food and Drug Officials of I'.S. Quart. Bull.16 126-132 (1952) .

22. E.L. LONG, ]nterna] report to Dr. A.T. Lehman, Division of

Pharmacology , rood and Drug Administration, I'.S.A. (July 31,

195q3 (by courtesv of Dr. Long to the author)•

23. J.R.~I. INNES, B.M. I'LLAND, M.C• VALERIO, L. PETRUC]ILL[, L.

FISHBEIN,E.R. HART, A.J. PALLOTTA, R.R. BATES, E.L. FALK, J.J.

GART,M. KLEJN, I. MITCHELL and J. PETERS, .I. Natl. Cancer Inst. 42 ii01 (1060) .

24. U.S. Environmental Protection Agency, Compendium of Registered Pesticides,Vo]. 111, JIT-R-3.1. (1972).

25. ~. COSALVEZ and J. MERCHAN, Cancer Res. 33 3047-3050 (]~73) .

26. }[. GOSALVEZ, J..]. DIAF-G]L, J. COLOMA and L. SALCANICOFF, Brit. J. Cancer 36 243-253 (1977) .

27. 3. MERCHA~J, d.J. DIAZ-~IL, }~.A. FIef'ERAS, M.A. NAVARRI], P.

VILADIU and }~. GOSAI~VEZ, Rev. Esp. I)ncol . 25 107-120 (1978) . 28. J.,]. DIAZ-C. IL and N. GOSALVEZ. U6dicine Biologie Environne-

ment 4, no. 2, 447-453 (1976) .

29. M. O. OSALVEZ, ,T.J. D]AZ-CIL, J.J. ALCAqlZ and A. BORRELL, Bio- chem. Soc. Transac. 7 i]3-116 (iO70) .

30. ANON. ,Environmental Protection Azencv , Lists of pesticides

that mnv be too dangerous to use. C and E News, Uashington, D.C. p. 18, (,June 14, ]976) .

31 . R. I . FREUDENTAL,D•C. THAKE and R.L. BARON, Project Summary- CarcinoGenic Potential of Rotenone: Subchronic Oral and Per\- tonea| Administration to Rats a n d Chronic Dietary Administra-

tion to Syrian Colden Uamsters, United States Environmental

Protection Agency, doc'um~nt EPA-600/S]-81-037, IIealth Effects Research Laboratory, Research 'triangle Park (N.C.) (]08]) .

32. }I. COSAIJVEZ and M• BI+ANCO, unpub] is}led ~-esults .

carcinogenesis with the insecticide rotenone

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