Lyman W. Condie

Genotoxic properties of municipal wastewaters in Ohio

Wastewaters from six municipal wastewater treatment plants in Ohio were tested at different stages of treatment for mutagenicity in the Ames/Salmonella assay. The chlorinated secondary effluents were also evaluated for induction of sister chromatid exchanges in Chinese hamster ovary cells. Direct-acting microbial mutagenicity was observed for extracts of the effluents from all six plants for both an initial and a repeat sampling series. In some cases, the mutagenicity was greatly enhanced by S9 metabolic activation (MA). In general, the specific mutagenicity of the extracts increased following activated sludge treatment. Chlorination resulted in substantial increases in mutagenic activity for some of the Wastewaters but had no effect on others. SCE inducing activity was detected in five out of six extracts for the first sample series, and for two out of five extracts for the second sample series. There was no obvious correlation in the ability of the extracts from the chlorinated secondary effluents to induce SCE in CHO cells and to induce mutations in Salmonella.

Interactions of Water Contaminants I. Plasma Enzyme Activity and Response Surface Methodology following Gavage Administration of CCl4 and CHCl3 or TCE Singly and in Combination in the Rat

The joint hepatotoxicity of CCl4 and CHCl3 or TCE in male CD rats following simultaneous oral administration has been investigated. Rats with chronic indwelling arterial cannulas were administered a single oral dose of CCl4 and CHCl3 or CCl4 and TCE in 5% Emulphor at doses of 0 to 700 mg/kg. Hepatotoxicity was evaluated by measuring the activity of AST, ALT, and SDH in plasma at 0, 3, 6, 12, 24, 36, 48, and 72 hr postgavage. Response data were analyzed for interaction using response surface methodology. CCl4 alone displayed dose-dependent toxicity. TCE demonstrated little evidence of hepatotoxicity. In combination, both CCl4/CHCl3 and CCl4/TCE displayed a synergistic (supraadditive) response for peak plasma enzyme activity.

Comparative Renal and Hepatotoxicity of Halomethanes: Bromodichloromethane, Bromoform, Chloroform, Dibromochloromethane and Methylene Chloride

The renal and hepatotoxicities of five selected halomethanes, which are drinking water contaminants, were evaluated following a 14-day exposure. Bromodichloromethane, bromoform, chloroform, dibromochloromethane and methylene chloride were administered at three dose levels. Toxicity was evaluated by measuring changes in total body weight, uptake of p-aminohippurate into renal cortical slices, blood urea nitrogen, serum creatinine, and serum glutamate-pyruvate transaminase levels and by performing a histopathologic examination of liver and kidney tissues. Dose-related effects on the liver and kidney were detected with the uptake of p-aminohippurate into kidney slices and with the histopathologic evaluation of tissues. Treatment-related effects seen in the methylene chloride exposed mice were less pronounced as compared to the other halomethane treatment groups. In general, histopathological changes were the most sensitive indicators of both liver and kidney damage.

Subacute and Subchronic Toxicity of Ethylene Glycol Administered in Drinking Water to Sprague-Dawley Rats

Subacute (10-day) and subchronic (90-day) toxicity studies of ethylene glycol (EG) were conducted in male and female Sprague-Dawley rats to provide the U.S. Environmental Protection Agencys (EPA) Office of Drinking Water with toxicity data for final preparation of a Health Advisory for the chemical. Ethylene glycol was administered in drinking water at concentrations of 0.5, 1.0, 2.0, and 4.0% for both sexes in the 10-day study. Based on a projected consumption rate of 100 ml/kg/day, the respective doses on a mg/kg/day basis would be 554, 1108, 2216, and 4432. These dose levels were also used in the 90-day study for females, but dose levels for the males in the 90-day study were 0.25, 0.5, 1.0, and 2.0% (227, 554, 1108, and 2216 mg/kg/day). At time of sacrifice necropsies were performed and tissues were prepared for histological evaluation. Blood samples were taken for hematology and clinical chemistry determinations. Body weights were measured weekly. Water and food consumption were determined three times weekly. No mortality occurred in the 10-day study. In the 90-day study 8/10 females and 2/10 males in the high dose group died prior to sacrifice. Body weights were suppressed in a dose response fashion for males and females. Hemoglobin, hematocrit, erythrocytes, and leukocytes were all significantly decreased in female rats receiving 4% EG for 10 days. The most significant histopathological findings, seen predominantly in males, were kidney lesions which included calcium oxalate crystals in tubules and pelvic epithelium; tubular dilation and degeneration; intratubular proteinaceous material; and inflammation in tubules and pelvic epithelium. At the same dose of ethylene glycol, males had more kidney lesions and much higher incidence and severity of lesions than the females.

Naphthalene Toxicity in CD-1 Mice: General Toxicology and Immunotoxicology

Random bred CD-1 mice were used to evaluate the acute oral toxicity and subchronic toxicity of naphthalene administered in corn oil. The acute oral LD50 of naphthalene was 533 and 710 mg/kg in male and female mice, respectively. Subchronic toxicity was evaluated with 14- and 90-day daily oral gavage studies. Doses utilized in the 14-day study were 27, 53, and 267 mg/kg, with the latter representing one-half of the male LD50. Both males and females demonstrated a 5-10% mortality and depressed body weight at the high dose only. Males had decreased thymus weights, and females had decreased spleen and increased lung weights at the high dose only. Other organ weights were unaffected at any dosage level. Serum enzyme and electrolyte levels were not altered in a dose-related manner. To assess the potential immunotoxicity of naphthalene the following screen was utilized: humoral immune response, response to mitogens, delayed hypersensitivity response, popliteal lymph node response, bone marrow stem cell number, and DNA synthesis. No evidence of immunotoxicity was demonstrated. The 90-day study employed daily oral doses of 5.3, 53, and 133 mg/kg. There was no treatment-related mortality in either sex, nor was body weight affected. Organ weights were not affected in males, and females showed reduced spleen weights only at the high dose. Serum enzyme and electrolyte levels, as well as the immunotoxicity screen, indicated that naphthalene doses up to one-fourth the LD50 for 90 days failed to elicit consistent statistically significant and biologically relevant compound-related effects. A screen of the effects of the 90-day naphthalene treatment on various aspects of the hepatic drug metabolizing system indicated no alterations, with the exception of a specific dose-related inhibition of aryl hydrocarbon hydroxylase activity in both male and female mice.

Effect of gavage vehicle on hepatotoxicity of carbon tetrachloride in CD-1 mice: corn oil versus Tween-60 aqueous emulsion.

This investigation was conducted to evaluate the effect of gavage vehicles on altering the severity of the subchronic hepatotoxicity of carbon tetrachloride (CCl4). Male and female CD-1 mice were gavaged with 0, 1.2, 12, and 120 mg/kg CCl4 in either a corn oil or 1% Tween-60 vehicle once daily for 5 consecutive days per week for 90 days. The study revealed that the hepatotoxicity was greater in the mid- and high-dose groups of mice that had received CCl4 administered in corn oil. Increases in serum enzyme activities were detected in the mid-dose groups of mice that were gavaged with CCl4 in corn oil. The serum enzyme activities were significantly higher in the high-dose groups of animals in which CCl4 was administered in corn oil. Histopathological findings indicated that hepatocellular changes following the administration of CCl4 at the mid- and high-dose levels were more frequent and more severe when CCl4 was given in corn oil than when it was administered in Tween-60. The experimental findings indicate that the no-observed-adverse-effect level from CCl4 exposure was lowered by an order of magnitude (from 12 to 1.2 mg/kg) and that the hepatotoxicity of CCl4 was enhanced in the high-dose treatment groups when corn oil was employed as the gavage vehicle.

Acute toxicity of monochlorophenols, dichlorophenols and pentachlorophenol in the mouse

Acute oral LD50 values were determined for 2-, 3-, and 4-chlorophenol, 2,3-, 2,4-, 2,5-, 2,6-, 3,4-, and 3,5 dichlorophenol and pentachlorophenol in male and female mice. LD50 values (mg/kg) ranged from 117 (females) and 177 (males) for pentachlorophenol to 2389 (females) and 2643 (males) for 3,5-dichlorophenol. It was found that 2-chlorophenol and 3-chlorophenol were considerably more toxic than the dichlorophenol series. Values for males and females were generally similar, the major differences being with pentachlorophenol and 2,5-dichlorophenol, where in both cases the female LD50 was lower.

Chemical reactivity, cytotoxicity, and mutagenicity of chloropropanones.

Studies were conducted to assess the in vitro toxicity of three chloropropanones: monochloropropanone (MCP), 1,1-dichloropropanone (1,1-DCP), and 1,3-dichloropropanone (1,3-DCP). Chloropropanones reacted directly with reduced glutathione (GSH) in sodium phosphate buffer at pH 7.4. All chloropropanones were cytotoxic to suspensions of male rat hepatocytes in a concentration range of 0.5-10 mM. Cytotoxicity was preceded by rapid decline in cellular GSH levels. Mutagenic potencies among the chloropropanones in Salmonella typhimurium bacteria differed greatly. 1,3-DCP was mutagenic in the nanomole range, 1,1-DCP was weakly mutagenic in the micromole range, and MCP was not mutagenic. Mutagenicity of the dichloropropanones was evident without metabolic activation. These results suggest that the three chloropropanones may, in part, be directly cytotoxic but only 1,3-DCP and 1,1-DCP are directly mutagenic.

Acute, 14-Day Repeated Dosing, and 90-Day Subchronic Toxicity Studies of Carbon Tetrachloride in CD-1 Mice

CD-1 mice received carbon tetrachloride daily by gavage for 14 or 90 consecutive days. Corn oil was the vehicle used. The 14-day study involved doses of 625, 1250, and 2500 mg/kg; the 90-day subchronic study involved doses of 12, 120, 540, and 1200 mg/kg. The 14-day study revealed a dose-dependent mortality and decreased body weight in males, whereas females demonstrated mortality only at the high dose. Other dose-dependent findings included decreased fibrinogen and lymphocytes; increased LDH, SGPT (ALT), and SGOT (AST); increased liver weights and ratios in both sexes; and decreased lung, thymus, and kidney weights in males only. There were no compound-related deaths in the 90-day study. There were no consistent compound-related effects on any of the hematological or urinary parameters evaluated. LDH, SGPT (ALT), SGOT (AST), ALP, cholesterol, and bilirubin were increased in an apparent dose-dependent manner while blood glucose levels decreased at all dosage levels. Liver, spleen, and thymus weights and ratios were increased at all dosage levels in both sexes. Histopathology revealed no kidney damage, but liver damage was observed at all doses in both sexes. A no-observable-adverse-effect level was not obtained in these studies.

Short-Term Toxicity (One-and Ten-Day Gavage) of Barium Chloride in Male and Female Rats

To assess adverse effects that might be caused by an event resulting in high levels of barium in drinking water, rats were gavaged with barium chloride (BaCl2 at dosage levels of 30, 100, and 300 mg/kg in a 1-day study and at 100, 145, 209, and 300 mg/kg for 10 days, and the effects were determined. LD50 values for male and female rats were found to be 419 (352–499) and 408 (342–487) mg/kg BaCl2, respectively. In the 1-day exposure study, decreases in body weight and liver/brain weight ratios and increase in kidney weight as a percentage of body weight appeared to be related to barium ingestion at 300 mg/kg. After 10 days of exposure to barium, survival of females was substantially lower at 300 mg/kg. A reduction in ovaries/brain ratio at 300 mg/kg appeared to be barium-induced. There was a decrease in BUN at 300 mg/kg in males and at all dose levels in females. No other effects were attributed to barium. Histopathological findings were negative in both the 1-and 10-day studies. It is concluded that short-term oral exposure to BaCl2 at doses up to 209 mg/kg produces no significant adverse health effects.