D. Polin

An ecotoxicological study of a population of the white footed mouse (Peromyscus leucopus) inhabiting a polychlorinated biphenyls-contaminated area

White footed mice (Peromyscus leucopus) inhabiting an area surrounding a pond (Tyler) contaminated with polychlorinated biphenyls (PCBs) and metals (Cadmium, Zinc, Copper) had whole body burdens of 0.42–4.17 ppm PCBs (mean 2.3 ppm) and animals from a comparison non-polluted site (WCC) had no detectable PCBs. Males and females caught at the polluted site in the winter months were not significantly different in body weight or length when compared to WCC animals, but Tyler animals had significantly increased relative liver, kidney, spleen and adrenal weights. In the summer months, mostly males were caught at both Tyler and WCC sites. Tyler males were significantly lighter than WCC males, and had a significantly increased relative liver weight when compared to the males from the WCC site. In addition, the adult Tyler males had significantly lower relative testis weights. At Tyler there was a significantly smaller proportion of juveniles and subadults in the population than at WCC. Polychlorinated biphenyls levels in the adult Tyler males were significantly positively correlated with relative liver weight, but there were no significant correlations with any of the other structures measured. These results suggest that at the polluted site there is inhibition of reproduction and changes in liver, spleen, adrenal, and testis function.

The reproductive effects of dietary heptachlor in mink (Mustela vison)

Adult female mink were fed diets containing 0 (control), 6.25, 12.5, and 25 ppm (μg/g) technical grade heptachlor prior to and throughout the reproductive period (181 days) to evaluate the effects of heptachlor consumption on reproduction and offspring viability and to assess the extent of placental and mammary transfer of heptachlor epoxide to mink offspring. Feeding 12.5 and 25 ppm resulted in significant reductions in feed consumption and body weights of female mink. Mortality was 0, 8, 67, and 100% for the control, 6.25, 12.5, and 25 ppm groups, respectively. All females in the 25 ppm group died within 88 days. Mink fed the two higher heptachlor diets displayed clinical signs indicative of central nervous system involvement just prior to death. Females were mated with males on the same dietary treatments. Whelping success rates were 67, 83, 27, and 0% for the control, 6.25, 12.5, and 25 ppm groups, respectively. High mortality in the 12.5 and 25 ppm groups accounted for the lack of reproductive success. Gestation length, litter size and birth weight of kits were not significantly affected by adult female consumption of 6.25 ppm heptachlor while kits whelped by females on the 12.5 ppm diet weighed significantly less than control kits at birth. Survival of kits in the 12.5 ppm group from birth to three weeks of age was also adversely affected. At three and six weeks of age, kit body weights in both the 6.25 and 12.5 ppm groups were significantly less than body weights in control kits. Examination of heptachlor epoxide concentrations in newborn and developing kits indicated both placental and mammary transfer of the chemical from the dams to the kits. The LC50 for the 181-day exposure period for female mink was 10.5 ppm heptachlor and the LOAEL, based on reduced kit growth, was 6.25 ppm.

Urinary cyclic AMP excretion in birds: Dependence on parathyroid hormone activity

The cyclic AMP response of avian kidney to parathyroid activity has been evaluated both in vitro and in vivo. The production of cyclic AMP by dispersed avian kidney cells was stimulated by bovine parathyroid hormone or by an extract of avian parathyroid glands. Intravenous infusion of bovine parathyroid hormone resulted in increased urinary excretion and plasma concentration of cyclic AMP, as well as increased plasma calcium and urinary phosphorus excretion. The increases in plasma and urinary cyclic AMP preceded those of plasma calcium and of phosphorus excretion. EDTA infusion resulted in a decrease in plasma calcium and an increase in urinary cyclic AMP excretion. After 10 days on a low-calcium diet, chickens exhibited a 4.5-fold increase in urinary cyclic AMP excretion. The results suggest that urinary cyclic AMP in chickens reflects PTH activity similar to some mammalian species.

Enhanced withdrawal from chickens of hexachlorobenzene (HCB) and pentachlorophenol (PCP) by colestipol, mineral oil, and/or restricted feeding.

Young chickens fed hexachlorobenzene (HCB) or pentachlorophenol (PCP) for 14 d at 10 ppm in the diet contained body burdens of 573 or 362 micrograms, respectively. These diets were withdrawn (d 0) and replaced for 21 d with diets containing 5% mineral oil (MO), or 5% colestipol (CO), a bile-acid-binding resin, or the chickens were restricted in feed intake to 50% of controls (50-RF), fed MO plus 50-RF, or CO plus 50-RF. Without any treatment during withdrawal, body burdens were reduced to 63% and 70% of the d 0 values for HCB and PCP, respectively. MO, CO, or 50-RF reduced body burdens of HCB to 37% of d 0 burdens, but the combination treatments with 50-RF reduced body burdens to 19% of d 0 values. PCP was at 35% of the d 0 burdens from 50-RF, while all other treatments had reduced body burdens to nondetectable amounts of less than 0.7 micrograms/bird by d 21 of withdrawal. Body fat was not reduced by mineral oil, but was reduced to some extent by CO, and was markedly reduced by 50-RF. 50-RF always reduced body burdens of PCP or HCB alone or in combination with MO or CO. These data are discussed in relationship to the nonbiliary excretion of xenobiotics.

Colestipol and energy restriction as an approach to hasten removal of PBBs from chickens

Male White Leghorn chickens were fed either 0.1 or 1.0 ppm fireMaster FF-1 (FF-1) for 21 d. During the withdrawal phase, the chickens were fed 0, 0.5, or 2.5% colestipol hydrochloride, and anion exchange resin. Also, calories were restricted to 80% of control intake within certain groups during the first 14 d in each of 2 consecutive 21-d withdrawal periods. In the caloric-restricted groups, colestipol was fed at 0, 0.625, or 3.125% to yield equal daily intake of colestipol to those fed 0, 0.5, or 2.5% concentrations. During the first 21 d of withdrawal, colestipol at 2.5-3.125%, but not 0.5-0.625%, hastened excretion of polybrominated biphenyls (PBBs) by 50%. During d 22-42 of withdrawal, a background level of PBBs contamination was detected, which tended to confound the results. Despite this, higher levels of colestipol lowered overall body burdens of PBBs by 80% in comparison to the overall level of residues in the other groups of chickens, and by 20% in comparison to their own levels 21 d earlier. Dietary colestipol resulted in chickens with lower carcass lipid content. The combination of energy restriction plus colestipol at 2.5-3.125%, which had the greatest impact in reducing body weight gain and carcass lipid, seemed to be the most favorable treatments for hastening excretion of PBB residues.

Effect of Congeners of Polybrominated Biphenyls on Hatchability of Chicken Eggs. I. 2,2′,4,4′,5,5′-Hexabromobiphenyl vs. PBB

Summary The major component, 2,2′,4,4′,5,5′-hexabromobiphenyl (HBB-4) of the polybrominated biphenyl fireMaster FF-1, involved in the contamination problem in Michigan, did not produce either an edema in embryos and newly-hatched chicks or a decline in hatchability when fed to laying chickens. However, fireMaster FF-1, containing an equivalent level of the HBB-4 isomer caused the expected deleterious effects.

Polybrominated biphenyls in chicken eggs vs. hatchability.

Summary A relationship between polybrominated biphenyl, Firemaster FF-1 (FF-1), in the diet, and eggs, as monitored by hexahromobiphenyl (6-BB), and embryo toxicity, as measured by hatchability, were examined. The minimum dietary level of FF-1 for an effect on hatchability was estimated at 42 ppm, which produced an egg residue estimated at 65.9 ppm 6-BB. Generally, as FF-1 in the diet increased, egg residues increased and hatchability decreased. Regression equations were established for these relationships. After withdrawal of FF-1 in the diet, hatchability returned to normal when FF-1 treatments had been <625 ppm. Over a range of 30-85 ppm 6-BB in eggs there was poor correlation to an effect on hatchability. These latter data were discussed in terms that the 6-BB peak may not be a definitive approach to assess FF-1 toxicity. The authors express their appreciation for assistance in this project to Mr. Sulo Hulkonen, Mr. Edward Kowaleski, Mr. Dennis Dodson, and Ms. Melinda Neff.

Elimination of PBBs in rats. effect of mineral oil and/or feed restriction

Rats were fed polybrominated biphenyls (PBBs) at 0.1 to 100.0 ppm for 14 d and then treated to hasten the removal of PBBs with 0, 5, or 10% mineral oil (MO) and/or 0, 15, 30, or 45% feed restriction (FR) for 21 d. PBB body burdens were determined at d 14 and expressed on a log-log basis by Y = 0.91X + 2.179 (r2 = 0.974), where X = log of PBB concentration in diet (ppm) and Y = log of PBB body burden (micrograms). After 21 d withdrawal, body burdens were expressed by the equation Y = 0.787X + 2.218 (r2 = 0.95). The most effective withdrawal treatment was 10% MO + 45% FR producing a reduction of body burdens inversely related to prior body burdens (69% at 0.1 ppm to 23% at 100 ppm). Body weights and fat content were significantly (p less than or equal to .05) reduced by feed restriction, with fat content only 39% of controls at 21 d off. Mortality averaged 0, 13.6, and 35.8% for rats fed 0, 5, or 10% MO, and 25, 15, 8.6, and 3.7% for rats feed restricted at 0, 15, 30, and 45%, respectively. Histopathology of the dead and moribund rats indicated that the clinical signs were not characteristic of PBB toxicity. In a second experiment, safflower oil at 3.5% or excess vitamins prevented the mortality and clinical signs associated with MO during withdrawal from 100 ppm PBBs. Based on these data and those in the literature, PBBs interfere with vitamin utilization.

The efficacy of mineral oil combined with feed restriction in enhancing the elimination of heptachlor epoxide from mink (Mustela vison).

Adult female mink previously fed diets containing 0 (control) and 6.25 mg heptachlor/kg diet for 181 days were fed either the same control diet ad libitum (AL) or the control diet containing 10% mineral oil and restricted by 45% of ad libitum intake (MO/R) for 21 days to determine the efficacy of the latter treatment in enhancing the elimination of heptachlor epoxide (HE) from mink. Kit mink (2–3 months of age) whelped by dams of the control and 6.25 mg/kg groups were also fed the MO/R or AL diets for 21 days. Daily consumption (g/kg bw/day) of the AL diet by kit mink was significantly greater than consumption of the same diet by the adult females. Body weights of the control adults and the control and 6.25 mg/kg kits were significantly reduced by feeding the MO/R diet. Two adults from the control group and one adult from the 6.25 mg/kg group fed the MO/R diet died during the 21-day period. No mortalities occurred in kit mink fed either diet. Administration of the MO/R diet caused a significant reduction in body fat of the control adults and kits, but not in the 6.25 mg/kg adults and kits. Decreases in body fat of the MO/R groups were not associated with greater elimination of HE when compared to the AL groups. Comparison of HE body burdens in adult female and kit mink from the former 6.25 mg/kg heptachlor group at day 21 indicated that consumption of the MO/R diet did not increase the elimination of HE when compared to day 21 HE body burdens in adults and kits fed the AL diet. Heptachlor epoxide body burdens were reduced by 78 (MO/R) and 80% (AL) in the 6.25 mg/kg adults, while HE elimination from the 6.25 mg/kg kits was 96 and 93%, respectively. The half-lives of HE in the adults were 9.1 (AL) and 10.9 (MO/R) days, and 4.9 (AL) and 4.6 (MO/R) days in the kits. These results indicate that HE is readily mobilized and eliminated from mink.