Teratogenicity of bifenox and nitrofen in rodents

Abstract

The teratogenicity of the diphenyl ether herbicide bifenox [2,4‐dichlorophenyl 3'‐carboxymethyl‐4'‐nitrophenyl ether] was compared to that of nitrofen [2,4‐dichlorophenyl 4'‐nitrophenyl ether] in rats and in mice. Neither compound increased prenatal mortality in mice. Because nitrofen causes both malformations that are compatible with survival to weaning and a high incidence of perinatal (but not of fetal) mortality, emphasis was placed on postnatal parameters of bifenox toxicity. In rats, bifenox caused a low incidence of “bloody tears”;, but it did not decrease survival to term or to weaning in rats or mice, and did not reduce Harderian gland weight in mice. Because the weight of the Harderian glands is a more objective measure of their status than is the presence of an eye discharge, it is concluded that bifenox is not teratogenic at the levels administered. Nitrofen decreased litter size, pup weight, and Harderian gland weight in mice.     

Dioxin and dioxin-like PCB impurities in some Japanese agrochemical formulations

The profile and amount of dioxin impurity in agrochemicals were studied through detailed analysis of historic Japanese formulations. The chemicals analyzed include pentachlorophenol (PCP), 2,4,6-trichlorophenyl-4'-nitrophenyl ether (chloronitrofen, CNP), 2,4-dichlorophenyl-4'-nitrophenyl ether (nitrofen, NIP), tetrachloro-iso-phthalonitrile (chlorothalonil, TPN), 2-methyl-4-chloro-phenoxyacetic acid (MCP) and 2,4-dichlorophenoxyacetic acid (2,4-D). Among the six, two herbicides, PCP and CNP, produced during the 1960s and 1970s, contained very high concentrations of PCDD/DFs and TEQ. Others contained relatively low concentrations of PCDD/DFs. Dioxin-like PCB concentrations in all chemicals studied were low and their contributions to TEQ were negligible. The total dioxin emissions from the use of agrochemicals in Japan during the past 40 years (1955-1995) were estimated to be about a few hundred thousand kg of PCDD/DFs and 250 kg of WHO-TEQ from PCP and 190 x 10(3) kg of PCDD/DFs and 440 kg of WHO-TEQ from CNP. The major dioxin congeners present in PCP formulations were highly chlorinated PCDD/DFs that can be formed by the coupling of PCP and/or 2,3,4,6-tetrachlorophenol, and those in the CNP formulations were tetra- to hexa-chlorinated PCDD/DFs that can be formed from 2,4,6-trichlorophenol and/or 2,3,4,6-tetrachlorophenol.     

Decreasing ice coverage will reduce the breeding success of Baltic grey seal (Halichoerus grypus) females

Baltic grey seals (Halichoerus grypus) alternate between land and ice breeding, depending on ice conditions. We show that the fitness of grey seal females in terms of pup mortality and quality is reduced when breeding on land as compared with ice. The mean preweaning mortality rate on land was 21.1% (range 0% to 31.6%), and correlated with birth density (range 0.5-5.2 pups 100 m(-2)). The mean mortality rate on ice was 1.5%, where the highest density was 0.2 pups 100 m(-2) in particularly dense breeding groups. Mean weights of pups born on ice were significantly greater (48.3 +/- 8.1 kg) at the onset of moult as compared with pups born on land (37.4 +/- 7.8 kg). Because indices of life-time net reproductive rate (pup survival) and pup quality (weaning weight and health) were more auspicious on ice as compared with land, diminishing ice fields will lower the fitness of Baltic grey seal females and substantially increase the risk for quasi-extinction.     

Toxicological assessment of chlorinated diphenyl ethers in the rat, Part II

Chlorinated diphenyl ethers (CDE's) are environmental contaminants that have been found in Great Lakes fish. Because of the paucity of toxicity data and potential for human exposure, the present short-term study was conducted to assess their potential toxic effects. Groups of 10 male and 10 female rats were administered the three CDE congeners (2,2',4,4',5-pentachlorodiphenyl ether (PCDE), 2,2',4,4',5,5'-hexachlorodiphenyl ether (HCDE), 2,2',3,4,4',6,6'-heptachlorodiphenyl ether (HPCDE] in diets at levels of 0.5, 5.0, 50 or 500 ppm for a period of 4 weeks. Decreased food consumption was observed with male and female rats fed the diet containing 500 ppm HPCDE. Treatment with the three isomers at the highest dose level produced an increase in liver weight in both sexes. While administration of PCDE produced an increase in hepatic aminopyrine demethylase activity, HCDE caused a significant increase in aminopyrine demethylase, aniline hydroxylase and ethoxyresorufin de-ethylase activities. HPCDE caused a significant increase in ethoxyresorufin de-ethylase activity. HPCDE at the highest dose level also caused a significant reduction in circulating lymphocytes in male rats. The 3 CDE's produced mild and adaptative histological changes in the liver and thyroid, but only HPCDE elicited mild changes in the thymus, bone marrow, and spleen. The above data indicate that HPCDE is immunosuppressive and that all three CDE isomers are considered to be moderately toxic in rats. The no-observable effects levels appear to be between 5-50 ppm in diet (0.36-3.0 mg/kg b.w.) for the three CDE's.     

Reproduction in mice treated with crufomate: effects of dermal treatments on female mice and on their progeny.

Dermal treatments with crufomate 100 or 50 mg/kg or crufomate vehicle 100 mg/kg were applied to mice either on days 35 and 21 before mating or on days 70, 56, 35, and 21 before mating. Two, but not four dermal treatments, with both doses of crufomate reduced the mating reponse and conception rate in mice. The mice either did not produce a litter or the litter died before the age of 7 days. Four treatments with crufomate 100 mg/kg, but not with 50 mg/kg, reduced the weaning weight of progeny weaned at the age of 21 days. The vehicle had no effects on reproduction and increased the weights at maturity of female and male progeny of mice given two and four treatments, respectively.     

Developmental exposure to diuron causes splenotoxicity in male Sprague-Dawley rat pups

This study investigated whether perinatal exposure to diuron [3-(3,4-dichlorophenyl)-1-1-dimethylurea] might exert adverse effects on rat lymphoid organs. Pregnant Sprague-Dawley (SD) rats were exposed to diuron at 500, 750 or 1250 ppm in the diet from gestational days (GD) 12–21 and during lactation. At postnatal day (PND) 42, male pups were euthanized and thymus, spleen, mesenteric lymph node and femur were collected for histopathological analysis. Food consumption and body weight gain were significantly reduced in dams exposed to 1250 ppm during gestation period. Also, Diuron at 750 and 1250 ppm produced: (1) increased relative spleen weight associated histologically with severe congestion in red pulp, (2) enhanced extramedullary hematopoiesis and hemosiderosis as well as (3) depletion of lymphoid follicles in white pulp. Flow cytometric analysis revealed a significant reduction in B lymphocytes (CD45RA+) in male pups but T lymphocytes (CD4+, CD8+ and CD4+/CD8+) were not markedly affected. Thus, data suggest that Diuron-induced maternal toxicity in dams exposed to high dose and perinatal exposure to this herbicide produced spleen toxicity as evidenced by a reduction in B lymphocyte number in male SD pups.     

Developmental exposure to diuron causes splenotoxicity in male Sprague-Dawley rat pups

This study investigated whether perinatal exposure to diuron [3-(3,4-dichlorophenyl)-1-1-dimethylurea] might exert adverse effects on rat lymphoid organs. Pregnant Sprague-Dawley (SD) rats were exposed to diuron at 500, 750 or 1250 ppm in the diet from gestational days (GD) 12-21 and during lactation. At postnatal day (PND) 42, male pups were euthanized and thymus, spleen, mesenteric lymph node and femur were collected for histopathological analysis. Food consumption and body weight gain were significantly reduced in dams exposed to 1250 ppm during gestation period. Also, Diuron at 750 and 1250 ppm produced: (1) increased relative spleen weight associated histologically with severe congestion in red pulp, (2) enhanced extramedullary hematopoiesis and hemosiderosis as well as (3) depletion of lymphoid follicles in white pulp. Flow cytometric analysis revealed a significant reduction in B lymphocytes (CD45RA+) in male pups but T lymphocytes (CD4+, CD8+ and CD4+/CD8+) were not markedly affected. Thus, data suggest that Diuron-induced maternal toxicity in dams exposed to high dose and perinatal exposure to this herbicide produced spleen toxicity as evidenced by a reduction in B lymphocyte number in male SD pups.     

Long-term toxicology and carcinogenicity of 2,4,6-trichlorophenol

Carcinogenesis bioassays were conducted by giving 2,4,6-trichlorophenol [2,4,6-TCP] in feed to groups of 50 male and female Fischer rats and male B6C3F1 mice for two years. Dietary concentrations were 0 [20/group], 5000 [0.5%], or 10,000 [1%] ppm. Female mice began with 10,000 and 20,000 ppm but after 38 weeks were lowered due to reduced body weights to 2500 and 5000 ppm for 67 weeks; exposures averaged 5200 and 10,400 ppm. Adverse effects at two years were leukocytosis and monocytosis of peripheral blood and hyperplasia of bone marrow in both sexes of rats. In mice, liver toxicity, including individual liver cell abnormalities, focal areas of cellular alteration, and focal and nodular areas of hyperplasia were commonly present. Regarding carcinogenic activity, TCP caused leukemias/lymphomas in male rats, and possibly in female rats and female mice as well, and induced liver tumors in male and female mice. Using NTP categories of evidence indicates ‘clear evidence of carcinogenicity’ for male rats [hematopoietic system tumors]; ‘equivocal evidence of carcinogenicity’ for female rats [hematopoietic system tumors]; ‘clear evidence of carcinogenicity’ for male and female mice [liver tumors].     

2,4-Dichlorophenoxy Acetic Acid Mineralization in Amended Soil

The application of municipal biosolid or liquid hog manure to agricultural soils under laboratory conditions at 20°C influenced the fate of the herbicide 2,4-D [2,4-(dichlorophenoxy)acetic acid] in soil. When 2,4-D was added to soil at agronomic rates immediately after the addition of manure or biosolids to a coarse-textured soil, the percentage of 2,4-D mineralized at 100 days was about 47% for both treatments, compared to only 31% for control soils without amendments. The enhanced 2,4-D mineralization as a result of amendment addition was due to an increased heterotrophic microbial activity, with the greatest increases in soil respiration occurring for soils amended with biosolids. When additions of 2,4-D were delayed for one, two, or four weeks after the amendments were applied, the additions of amendments generally reduced 2,4-D mineralization in soil, particularly for manure, indicating that the effect of amendments on enhancing soil microbial activities diminished over time. In contrast, the mineralization of 2,4-D in control soils was less dependent on when 2,4-D was applied in relation to pre-incubations of soil for zero, one, two, or four weeks. The effect of manure on decreasing 2,4-D mineralization in specific soils was as large as the effect of soil texture on differences in 2,4-D mineralization across soils. Because manure was not found to impact 2,4-D sorption by soil, it is possible that 2,4-D mineralization decreased because 2,4-D transformation products were strongly sorbed onto organic carbon constituents in manure-amended soils and were therefore less accessible to microorganisms. Alternatively, microorganisms were less likely to metabolize the herbicide because they preferentially consumed the type of organic carbon in manure that is a weak sorbent for 2,4-D.     

Effect of herbicide and soil amendment on growth and photosynthetic responses in olive crops

Diuron [3-(3,4-dichlorophenyl)- = 1,1-dimethylurea] and simazine (6-chloro-N(2), N(4)-diethyl-1,3,5-triazine-2,4-diamine) are soil-applied herbicides used in olive crops. The objective of this study is to investigate the combined effect of these herbicides and the amendment of soil with an organic waste (OW) from the olive oil production industry on the growth and photosynthetic apparatus of adult olive trees and to compare the results with those obtained by Redondo-Gómez et al. for two-year-old trees. For this purpose, growth rate, gas exchange and chlorophyll fluorescence parameters were measured in 38-year-old olive trees, after one and two months of soil herbicide treatment and/or OW amendment. Soil co-application of OW and herbicide increases the quantum efficiency of Photosystem II (PSII) and the assimilation of CO(2) in olive trees, which led to a higher relative growth rate of the branches and leaves in length. Herbicide treatment reduced the photosynthetic efficiency in olive trees after two months of soil application, while this reduction is evident from week one in younger trees.     

2,4-Dichlorophenoxy acetic acid mineralization in amended soil

The application of municipal biosolid or liquid hog manure to agricultural soils under laboratory conditions at 20 degrees C influenced the fate of the herbicide 2,4-D [2,4-(dichlorophenoxy)acetic acid] in soil. When 2,4-D was added to soil at agronomic rates immediately after the addition of manure or biosolids to a coarse-textured soil, the percentage of 2,4-D mineralized at 100 days was about 47% for both treatments, compared to only 31% for control soils without amendments. The enhanced 2,4-D mineralization as a result of amendment addition was due to an increased heterotrophic microbial activity, with the greatest increases in soil respiration occurring for soils amended with biosolids. When additions of 2,4-D were delayed for one, two, or four weeks after the amendments were applied, the additions of amendments generally reduced 2,4-D mineralization in soil, particularly for manure, indicating that the effect of amendments on enhancing soil microbial activities diminished over time. In contrast, the mineralization of 2,4-D in control soils was less dependent on when 2,4-D was applied in relation to pre-incubations of soil for zero, one, two, or four weeks. The effect of manure on decreasing 2,4-D mineralization in specific soils was as large as the effect of soil texture on differences in 2,4-D mineralization across soils. Because manure was not found to impact 2,4-D sorption by soil, it is possible that 2,4-D mineralization decreased because 2,4-D transformation products were strongly sorbed onto organic carbon constituents in manure-amended soils and were therefore less accessible to microorganisms. Alternatively, microorganisms were less likely to metabolize the herbicide because they preferentially consumed the type of organic carbon in manure that is a weak sorbent for 2,4-D.     

Influence of plants on the chemical extractability and biodegradability of 2,4-dichlorophenol in soil

This study investigated the fate and behaviour of [UL-(14)C] 2,4-dichlorophenol (DCP) in planted (Lolium perenne L.) and unplanted soils over 57 days. Extractability of [UL-(14)C] 2,4-DCP associated activity was measured using calcium chloride (CaCl(2)), acetonitrile-water and dichloromethane (DCM) extractions. Biodegradability of [UL-(14)C] 2,4-DCP associated activity was assessed through measurement of (14)CO(2) production by a degrader inoculum (Burkholderia sp.). Although extractability and mineralisation of [UL-(14)C] 2,4-DCP associated activity decreased significantly in both planted and unplanted soils, plants appeared to enhance the sequestration process. After 57 days, in unplanted soil, 27% of the remaining [UL-(14)C] 2,4-DCP associated activity was mineralised by Burkholderia sp., and 13%, 48%, and 38% of (14)C-activity were extracted by CaCl(2), acetonitrile-water and DCM, respectively. However, after 57 days, in planted soils, only 10% of the [UL-(14)C] 2,4-DCP associated activity was available for mineralisation, whilst extractability was reduced to 2% by CaCl(2), 17% by acetonitrile-water and 11% by DCM. This may be due to the effect of plants on soil moisture conditions, which leads to modification of the soil structure and trapping of the compound. However, the influence of plants on soil biological and chemical properties may also play a role in the ageing process.     

A two-generational reproductive toxicity study of zinc in rats

A two-generation reproductive toxicity study of zinc chloride (ZnCl(2)) was conducted in rats. F(o) male and female rats were administered 0.00 (control), 7.50 (low), 15.00 (mid) and 30.00 (high) mg/kg/day of ZnCl(2). Selected F(1) male and female rats were exposed to the same doses received by their parents (F(o)). Exposure of F(0) parental rats to ZnCl(2) showed significant reduction in fertility, viability (days 0 and 4), and the body weight of F(1) pups from the high-dose group but caused no effects on litter size, weaning index, and sex ratio. Similarly, the continued exposure of F(1) parental rats to ZnCl(2) also reduced fertility, liter size, viability (day 0), and the body weight of F(2) pups within the high-dose group but caused no effects on weaning index and sex ratio. Exposure of ZnCl(2) to F(0) and F(1) parental males resulted in a significant reduction in their body weights, and the F(0) and F(1) parental females did not show any significant difference in their body weights compared to their control groups. However, the postpartum dam weights of both F(0) and F(1) female rats were significantly reduced compared to their controls. Exposure of ZnCl(2) to F(o) and F(1) generation parental rats did not produce any significant change of their clinical signs as well as their clinical pathology parameters, except the alkaline phosphotase (ALK) level, which showed an upward trend in both sexes of both generations. Exposure of ZnCl(2) to F(0) rats resulted in a reduction of brain, liver, kidney, spleen and seminal vesicles weights of males and in the spleen and uterus of females. Similarly, exposure of F(1) rats to ZnCl(2) also resulted in reduction of brain, liver, kidney, adrenal, spleen, prostate and seminal vesicles weights of males and in spleen and uterus of females. ZnCl(2) exposure resulted in grossly observed gastro-intestianla (GI) tract, lymphoreticular/hematopoietic, and reproductive tract lesions in parental rats in both generations. Reduced body fat was also recorded in F(1) parental rats.     

Effect of maternal dietary hexachlorocyclohexane exposure on pup survival and growth in albino rats

Abstract

In adult albino rats, maternal dietary. ß‐ and ?‐hexachlorocyclohexane (HCH) intake during gestation upto 400 ppm level did not affect the number of litters produced. But about 50 and 100% pup mortality was found in 200 and 400 ppm ß ‐HCH group within 5 days of birth. Maternal mortality was observed in 800 ppm ß ‐HCH group during third week of gestation. The effect of maternal dietary intake of HCH isomers at 50 and 250 ppm level during gestation and/or lactation on perinatal development was also studied. The body weights and sizes of the newborn litters of mother rats exposed to dietary HCH isomers did not. differ from controls. Similarly, the growth and development of the litters of HCH exposed mother rats that survived 28 day lactation period were found to be comparable to controls as evidenced by the body weight and weight of vital organs. However, liver weight increases were found in the 28 day weaned litters wherever the mothers had been exposed to HCH isomers during lactation. Lowered kidney weight was seen in litters of mother rats fed 250 ppm ?‐HCH during gestation and lactation. The brain and testis weights were not affected in the litters of any experimental groups.     

Carcinogenicity of hexachlorocyclohexane (BHC) in pure inbred swiss mice.

Inbred Swiss mice were treated with technical BHC (1) orally with the diet or by intubation and (2) by skin painting. The total duration of the experiment was 80 weeks. There was no difference in body growth and mortality between the experimental and control groups. Symptoms of intoxication in the form of convulsions and tendency of circling in one direction with drooping ears were observed alongwith corneal opacity 40 weeks after the experiment. Oral BHC treatment resulted in a significant increase in the incidence of liver tumours and tumours of lymphoreticular tissue. Males and females were equally susceptible. Skin painting of mice did not significantly increase the incidence of tumour.     

Effects of benzo[a]pyrene as an environmental pollutant and two natural antioxidants on biomarkers of reproductive dysfunction in male rats

Benzo[a]pyrene (B[a]P) is an environmental toxicant and endocrine disruptor. Therefore, the aim of the present study was to investigate the toxicity of B[a]P in testis of rats and also to study the role of silymarin and thymoquinone (TQ) as natural antioxidants in the alleviation of such toxicity. Data of the present study showed that levels of testosterone, estrogen and progesterone were significantly decreased after treatment of rats with B[a]P. In addition, B[a]P caused downregulation of the expressions of steroidogenic enzymes including CYP17A1 and CP19A1, and decreased the activity of 17-β hydroxysteroid dehydrogenase (17β-HSD). Moreover, B[a]P decreased the activities of antioxidant enzymes including catalase (CAT), glutathione peroxidase (GP_X) and superoxide dismutase (SOD), and significantly increased free radicals levels in testis of male rats. However, pretreatment of rats with silymarin prior to administration of B[a]P was found to restore the level of free radicals, antioxidant status, and activities of steroidogenic enzymes to their normal levels in testicular tissues. Moreover, histopathological finding showed that silymarin recovered the abnormalities occurred in tubules caused by B[a] P in testis of rats. On the other hand, TQ showed pro-oxidant effects and did not ameliorate the toxic effects of B[a] P on the testicular tissue since it decreased antioxidant enzymes activities and inhibited the protein expression of CYP11A1 and CYP21A2 compared to control rats. Moreover, TQ decreased the levels of testosterone, estrogen, and progesterone either in the presence or absence of B[a]P. It is concluded that B[a]P decreased testosterone levels, inhibited antioxidant enzymes activities, caused downregulation of CYP isozymes involved in steroidogenesis, and increased free radical levels in testis. Moreover, silymarin was more effective than TQ in restoring organism health and alleviating the deleterious effects caused by B[a]P in the testis of rats. Due to its negative impact, it is highly recommended to limit the use of TQ as a dietary supplement since millions of people in the Middle East are using it to improve their health.

     

Vapour of the free acid of the herbicide 2,4-D is toxic to tomato and lettuce plants

Tomato and lettuce plants were exposed to vapour of the free acid of [14C-phenyl] 2,4-D at concentrations in the range 1-600 pg litre(-1) for periods of 6, 24 or 72 h. The rate of uptake of radiolabel by tomato was about twice that by lettuce at the same vapour concentration. Uptake rates were linearly related to external vapour concentration. The relationship between uptake and vapour concentration of 2,4-D for the two species was similar to published values for the butyl and iso-octyl esters. The distribution of herbicide residue in the plant immediately after exposure indicated that the apical leaves of lettuce are particularly active in assimilating vapour, whereas for tomato, leaf position had no influence. Forty days after exposure, both species showed symptoms of toxicity and reduction in shoot dry weight typical of similar doses of 2,4-D esters. It is concluded that the vapour of 2,4-D represents a potential hazard to susceptible plants, and that further work is needed to determine the conditions likely to lead to the production of vapour of the free acids of phenoxyalkanoic herbicides following spraying.     

Effects of spraying the herbicides 2,4-D and 2,4,5-T on a population of the tortoise Testudo hermanni in southern Greece

A population of the tortoise Testudo hermanni near Olympia in southern Greece was studied by mark-recapture from 1975 to 1984. Part of the site was sprayed with the herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) each year from 1980, producing symptoms of poisoning (swollen eyes, fluid discharge from the nose and immobility) in tortoises. Survival rates of tortoises 10 cm or larger were significantly lower in the affected areas, with extra mortality of about 34% year-1, against an annual survival rate of 0.85-0.90 in unaffected areas. Changing population structures showed that juveniles were even more strongly affected, with the proportion of juveniles in samples decreased by half. The population in the sprayed area declined to near zero by 1984, due to mortality rather than to emigration, since more movements were recorded into than out of the affected area. There was no difference in body mass condition between sprayed and unsprayed areas, showing that effects were acute; mortality was not due to starvation from loss of food plants. The scale and pattern of mortality was similar to that from a severe scrub fire; spraying is potentially more catastrophic since often repeated at shorter intervals than burning. Possible physiological mechanisms of death are discussed. The susceptibility of tortoises to 2,4-D and 2,4,5-T (or to associated dioxin impurities) presents a warning for conservation of these late-maturing animals.     

Persistence of hexaconazole, a triazole fungicide in soils

Persistence of hexaconazole (2-(2,4-dichlorophenyl)- 1-(1H-1,2,5-triazol-1-yl) hexan-2-ol) was studied in alluvial, red and black soils under flooded and nonflooded conditions. This fungicide was more persistent in all soils under flooded conditions than under nonflooded conditions and at 27 degrees C than at 35 degrees C. Degradation of hexaconazole in sterilized and nonsterilized soils proceeded at identical rates indicating a minor role of micro-organisms in its degradation. The soil persistence of hexaconazole was not affected by the addition of wheat straw both under flooded and nonflooded conditions.     

A two-generational reproductive toxicity study of zinc in rats

A two-generation reproductive toxicity study of zinc chloride (ZnCl₂) was conducted in rats. F_o male and female rats were administered 0.00 (control), 7.50 (low), 15.00 (mid) and 30.00 (high) mg/kg/day of ZnCl₂. Selected F₁ male and female rats were exposed to the same doses received by their parents (F_o). Exposure of F₀ parental rats to ZnCl₂ showed significant reduction in fertility, viability (days 0 and 4), and the body weight of F₁ pups from the high-dose group but caused no effects on litter size, weaning index, and sex ratio. Similarly, the continued exposure of F₁ parental rats to ZnCl₂ also reduced fertility, liter size, viability (day 0), and the body weight of F₂ pups within the high-dose group but caused no effects on weaning index and sex ratio. Exposure of ZnCl₂ to F₀ and F₁ parental males resulted in a significant reduction in their body weights, and the F₀ and F₁ parental females did not show any significant difference in their body weights compared to their control groups. However, the postpartum dam weights of both F₀ and F₁ female rats were significantly reduced compared to their controls. Exposure of ZnCl₂ to F_o and F₁ generation parental rats did not produce any significant change of their clinical signs as well as their clinical pathology parameters, except the alkaline phosphotase (ALK) level, which showed an upward trend in both sexes of both generations. Exposure of ZnCl₂ to F₀ rats resulted in a reduction of brain, liver, kidney, spleen and seminal vesicles weights of males and in the spleen and uterus of females. Similarly, exposure of F₁ rats to ZnCl₂ also resulted in reduction of brain, liver, kidney, adrenal, spleen, prostate and seminal vesicles weights of males and in spleen and uterus of females. ZnCl₂ exposure resulted in grossly observed gastro-intestianla (GI) tract, lymphoreticular/hematopoietic, and reproductive tract lesions in parental rats in both generations. Reduced body fat was also recorded in F₁ parental rats.