Ezra Berman

Observations of mouse fetuses after irradiation with 2.45 GHz microwaves.

Pregnant CD-1 mice were exposed to 2.45 GHz CW radiation for 100 min daily at a range of power densities (3.4-28 mW/cm2). Near-term fetuses were examined for gross external morphologic alterations. Mean live fetal weight per litter decreased significantly with exposure to the highest power density (sham, 0.97 2 0.15 g; irradiated, 0.89 * 0.13 g). There was a significantly increased incidence of cranioschisis in exposed fetuses. An exposure of the dam for 100 min at these power densities did not appear to be significant thermally. Estimates of mean dose rate as determined using twin-well calorimetry ranged from 2.0 to 22.2 mW/g.

Steroidogenic assessment using ovary culture in cycling rats: Effects of bis (2-diethylhexyl) phthalate on ovarian steroid production☆

In vitro ovary culture in rats was used to characterize ovarian steroidogenesis and to evaluate changes produced by in vivo exposure to bis(2-diethylhexyl)phthalate (DEHP). Steroid profiles [progesterone (P4), estradiol (E2), and testosterone (T)] from cultures of minced ovary were obtained in untreated immature and mature rats, and from mature rats treated with DEHP. A 1-h incubation without human chorionic gonadotropin (hCG) was used to produce an initial steroidogenic profile. Three 1-h incubations with hCG were used to produce a stimulated steroid profile. A combination of initial and stimulated ovarian steroid profiles was shown to correctly identify the stage of the cycle in all untreated rats, using multivariate statistical analysis. Separately, initial or stimulated ovarian steroid profiles correctly identified the stage of the cycle in more than 90% of the rats. The statistical analysis using a combination of variables (multivariate) indicated that DEHP-treated rats were significantly different (P < 0.001) from sham-treated rats. In fact, the alteration caused by DEHP in the in vitro ovarian steroidogenic profile was most apparent in rats during diestrus and estrus. In DEHP-treated rats in diestrus, ovarian steroidogenesis appeared to shift to the production of more T and more E2 than in untreated rats in diestrus. The change seen in steroid profiles in DEHP-treated rats in estrus is to decreased E2 production. The steroid profile from ovary culture in conjunction with vaginal cytology was very useful in correctly identifying in vivo DEHP-treated rats, and will be a useful in vitro technique in the evaluation of ovarian toxicants in cycling females.

A multidisciplinary approach to toxicological screening: I. Systemic toxicity

The toxicity of 10 chemicals, including pesticides (carbaryl, chlordane, heptachlor, and triadimefon), solvents (carbon tetrachloride, dichloromethane, tetrachloroethylene, and trichloroethylene), and industrial chemicals [diethylhexylphthalate (DEHP) and phenol] was examined in the liver, kidneys, spleen, thymus, and adrenals of female F344 rats after 1 or 14 d of oral dosing. For each chemical, 4 doses were based on fractions of the acute LD50, which was estimated using an abbreviated (up-and-down) method. A multivariate analysis (MANOVA) was conducted for each organ using selected measures of toxicity. A post hoc contrast analysis was also conducted for significant MANOVA results in order to determine effective and ineffective doses. A single dose of heptachlor resulted in necrotic lymphocytes in the spleen and thymus at doses > or = 23 mg/kg. Triadimefon altered liver and spleen weights; this effect has not been described previously. Dichloromethane (> or = 337 mg/kg/d for 14 d) increased the incidence of necrosis of individual centrilobular hepatocytes. Trichloroethylene-induced hepatotoxicity was obtained at doses an order of magnitude lower than those reported in the literature. Acute DEHP (150 mg/kg) increased mitotic figures in hepatocytes, which were replaced by hepatocellular cytomegaly after 14 d of dosing at the same level. Following phenol exposure, there was an increased incidence in hepatocellular necrosis at 1 d, and an increased incidence of kidney lesions at 1 and 14 d; these findings were considered to be the result of vascular stasis. Overall, the algorithm used to select doses was effective for both 1- or 14-d dosing regimens. For all chemicals except carbon tetrachloride, the lowest effective dose for systemic toxicity was within the range of 3-56% of the LD50 for acute dosing, and 1-30% of the LD50 for repeated administration.

Lethality and hepatotoxicity of complex waste mixtures.

Male F344 rats were exposed by gavage to samples of complex mixtures and evaluated 24 hr later. Seven of the 10 samples caused death at doses ranging from 1 to 5 ml/kg body wt. Eight of the 10 samples were hepatotoxic based on histopathologic evaluation; 6 were centrilobular and 2 were periportal hepatotoxicants. The waste samples exerted toxicity through different mechanisms, as indicated by differences in the severity and lobular location of the tissue damage. Nine of the 10 samples caused an increase in the ratio of liver weight to body weight (relative liver weight). With histopathological evaluation as the criterion, relative liver weight was the single best indicator of hepatotoxicity. Exposure to several of the waste samples increased serum total bilirubin and serum enzyme activities of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, alkaline phosphatase, and ornithine carbamyl transferase. As a battery, but not individually, the serum indicators separated the 8 hepatotoxic samples from the 2 nonhepatotoxic samples. In general, the hepatotoxicity of the waste samples did not appear to be readily predicted from (partial) chemical characterization data. An approach that includes both chemical characterization and biological testing should provide valuable information regarding the hazardous nature of complex wastes.

Decreased body weight in fetal rats after irradiation with 2450-MHz (CW) microwaves

Female Sprague-Dawley (CD) rats were exposed to 2450-MHz (CW) microwave radiation at incident power densities of 0 or 40 mW/cm2 (SAR = 6.0 W/kg) for 100 min daily on the sixth through 15th day of gestation. One-time exposure to the same conditions increased average colonic temperatures 2 degrees C at the end of irradiation in pregnant rats of similar size. There were 23 sham-irradiated and 24 microwave-irradiated females. When these groups were compared on the 21st day of gestation, no significant differences were found in pregnancy rates; in the numbers of live, dead or total fetuses; nor in the incidences of external, visceral or skeletal anomalies or variations. However, mean fetal body weight was significantly (p = 0.0008) lower after microwave irradiation and was 9% less than that of sham-irradiated litters. Sternal ossification was also significantly delayed in the microwave-irradiated fetuses (p = 0.007). It is concluded that even though a change in the malformation rate is not effected in rats, a fetotoxic effect does occur due to microwave-exposure conditions which raise maternal rectal temperatures to approx. 40 degrees C and produce a specific absorption rate (SAR) greater than or equal to 6 W/kg in the dam.

Altered steroidogenesis in whole-ovary and adrenal culture in cycling rats.

Cultures of minced, whole-ovary (whole-ovary culture) were used to determine if three selected chemicals altered steroidogenic profiles. First, phenolsulfonthalein (PST), when used in culture medium, was tested for its influence on in vitro steroidogenesis. Next, aminoglutethimide (AGTP; 0 or 150 mg/kg once) and di(2-ethylhexyl)phthalate (DEHP; 0 or 1500 mg/kg/day for 10 days) were administered in vivo to young adult cycling rats, and the ovaries and adrenals were removed and cultured for 1 h. Ovarian steroidogenic profiles of progesterone (P), testosterone (T), and estradiol (E) release into the medium were measured using radioimmunoassay techniques. PST in medium significantly decreased ovarian P production and altered T and E production so that the T/E ratio was significantly altered. Therefore, PST was excluded in the later studies. DEHP altered steroid profiles so that proestrus appeared to be delayed. AGTP decreased P and E production significantly, and T production was increased slightly in proestrus ovaries. These AGTP alterations in T and E resulted in a highly significant increase in the T/E ratio. Adrenals from the DEHP and AGTP experiments were also cultured for 1 h, and P was assayed in the medium. AGTP, but not DEHP, significantly increased the production of P in adrenals. Whole-ovary culture is recommended as an in vitro test for chemicals suspected of interfering with steroidogenesis in vivo. This test model should be placed strategically between in vivo studies of reproductive toxicity and complex in vitro mechanistic studies.

Hepatotoxic interactions of ethanol with allyl alcohol or carbon tetrachloride in rats

To assess whether potential toxic interactions occur between ethanol and allyl alcohol or carbon tetrachloride following subacute, concurrent chemical exposure, male Fischer 344 rats, approximately 70 d of age, were given ethanol at 0, 0.05, 0.1, 0.2, or 0.5 ml/kg in corn oil daily by gavage for 14 d (ETOH group), or the same levels of ethanol with 21 mg allyl alcohol/kg (ALAC group), or the same levels of ethanol with 20 mg carbon tetrachloride/kg (CCL4 group). Hepatic response was assessed 24 h after the last dose. Interactions were evaluated by comparing the ETOH group with either the ALAC group or the CCL4 group using multivariate analysis of variance procedures. No statistically significant interaction was seen between the ETOH group and the ALAC group at the dosages used. Although an interaction between ethanol and carbon tetrachloride given simultaneously was not statistically significant, a small interactive effect on weight gain from d 0 to termination was apparent (p = .057). Exposure to ethanol alone resulted in a concentration-dependent decrease in absolute and relative liver weight, with a threshold between 0.05 and 0.1 ml/kg. There was no histopathological evidence of hepatic damage with ethanol alone, and no effect on hepatic cytochrome P-450 and glutathione levels or on serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALK). Exposure to allyl alcohol alone resulted in significant increases in absolute and relative liver weights, liver glutathione, and periportal hepatocellular vacuolar degeneration. Exposure to carbon tetrachloride alone resulted in significant increases in absolute and relative liver weight, serum levels of ALT, AST, and ALK, and centrilobular hepatocellular vacuolar degeneration and necrosis. These observations indicate that subacute, concurrent exposure of ethanol with carbon tetrachloride or allyl alcohol at ethanol levels comparable to those reported in gavage vehicles did not result in interactive toxicity.

Chronic Exposure of Rats to 100-MHz (CW) Radiofrequency Radiation: Assessment of Biological Effects

A multidisciplinary approach was employed to assess the possible biological effects of chronic exposure of rats to 100-MHz continuous wave (CW) radiofrequency (RF) radiation. Pregnant dams and later their offspring were exposed daily for 4 hr for up to 97 days of age. Specific absorption rates (SARs) for rats of varying ages were determined by twin-well calorimetry. Between exposures, animals were evaluated using various developmental and biological indices. No difference was observed between 100-MHz-exposed and sham-exposed rats for complete blood counts, mitogen-stimulated response of lymphocytes, frequency of T- and B-lymphocytes, or antibody response to Streptococcus pneumoniae capsular polysaccharide. No mutagenic effect on the sperm cells of rats exposed for over 90 days to 100 MHz was observed using the Dominant Lethal Assay. The mean time to eye opening was significantly accelerated in exposed compared to sham-exposed rats. In rats exposed to 100 MHz, significant decreases in the activity of acetylcholinesterase were observed in the striatum and medulla oblongata of 22-day-old rats and in the midbrain of 40-day-old rats but not in 97-day-old animals.

Mutagenicity in Salmonella of hazardous wastes and urine from rats fed these wastes

15 hazardous industrial waste samples were evaluated for mutagenicity in the Salmonella plate-incorporation assay using strains TA98 and TA100 in the presence and absence of Aroclor 1254-induced rat liver S9. Dichloromethane/methanol extracts of the crude wastes were also evaluated. 7 of the crude wastes were mutagenic, but only 2 of the extracts of these 7 wastes were mutagenic; extracts of 2 additional wastes also were mutagenic. In addition, 10 of the crude wastes were administered by gavage to F-344 rats, and 24-h urine samples were collected. Of the 10 raw urines evaluated, 3 were mutagenic in strain TA98 in the presence of S9 and beta-glucuronidase. The 3 crude wastes that produced these 3 mutagenic urines were, themselves, mutagenic. Adequate volumes of 6 of the 10 raw urines were available for extraction/concentration. These 6 urines were incubated with beta-glucuronidase and eluted through Sep-Pak C18 columns; the methanol eluates of 3 of the urines were mutagenic, and these were the same 3 whose raw urines also were mutagenic. In general, the C18/methanol extraction procedure reduced the cytotoxicity and increased the mutagenic potency of the urines. To our knowledge, this is the first report of the mutagenicity of urine from rodents exposed to hazardous wastes. Based on the present results, the use of only strain TA98 in the presence of S9 might be adequate for general screening of hazardous wastes or waste extracts for genotoxicity. The urinary mutagenesis assay does not appear to be a useful adjunct to the Salmonella assay for screening hazardous wastes. The problems associated with chemically fractionating diverse types of hazardous wastes for bioassay are also discussed.

The use of cultured ovarian fragments to assess toxicant alterations in steroidogenesis in the sprague-dawley rat

This study was conducted to determine the utility of using steroid production by cultured ovarian fragments to assess toxicant-induced alterations in ovarian steroidogenesis in Sprague-Dawley rats. To this end, serum steroid concentration and steroid production (progesterone (P4), testosterone (T), estradiol (E2)) by cultured ovarian fragments is described during a normal 4-day estrous cycle. This culture system was then used to profile the effects of aminoglutethimide shown to have two sites of steroidogenic inhibition, side chain cleavage enzyme and aromatase. LH, FSH, P4, and E2 concentrations in serum during the 4-day estrous cycle confirmed that described in the literature for untreated rats. All of the steroids measured had peak production levels during proestrus. The patterns of P4 and E2 production by the ovaries in an unstimulated culture mimics that seen in serum. Stimulation with hCG (100 mIU/mL) after the initial 1 h culture tends to even out the production of P4, while T production rises faster and peaks earlier. The pattern and levels of estradiol production in hCG-stimulated cultures are very similar to those in the unstimulated culture, both in pattern and in production levels. When cultured ovarian fragments from proestrous rats were treated in vitro with aminoglutethimide (1 to 16 microM), the pattern of steroid production that characterized the inhibitory effects were similar to those reported in the literature using isolated cell culture procedures. This pattern showed a rapid decrease in E2 production (IC50 of 2.43 microM), a concurrent rise in T production, and a decrease in P4 production (IC50 of 15.5 microM). This culture system is an appropriate system to rapidly assess toxicant effects on ovarian steroidogenesis following in vivo or in vitro exposure.