Occupational chemicals tested for teratogenicity

Solvent use and time to pregnancy among female personnel in biomedical laboratories in Sweden

OBJECTIVES

To elucidate possible effects on fecundability from chemical, biological, and physical agents in laboratories, a retrospective study based on a questionnaire was conducted among female personnel who worked in Swedish biomedical research laboratories. Female personnel in non-laboratory departments were used as a reference group. The maximum number of women included in the analyses was 560. This corresponded to 2519 menstrual cycles. These women had given birth at least once during the period 1990-4.

METHODS

Time to pregnancy was used to estimate the fecundability-that is, probability of conception of a clinically detectable pregnancy per cycle. The fecundability ratio (FR) between exposed and unexposed cycles was calculated with a discrete time analogue of the Cox's proportional-hazards model. The FR estimates below unity indicate subfecundity.

RESULTS

Work with organic solvents in general in laboratory work, gave a decreased adjusted fecundability ratio (FR) of 0.79 (95% confidence interval (95 % CI) 0.68 to 0.93). Moreover, work with acetone and use of viruses also showed decreased FRs, 0.72 (0.53 to 0.97) and 0.66 (0.49 to 0.90), respectively.

CONCLUSIONS

The results of the present study give some indications of reduced fecundability for work with specific agents in laboratories, and support previously reported findings of a negative influence of organic solvents on fecundity among female laboratory personnel.

Metal-induced developmental toxicity in mammals: a review

It is well established that certain metals are toxic to embryonic and fetal tissues and can induce teratogenicity in mammals. The main objective of this paper has been to summarize the toxic effects that excesses of certain metals may cause on mammalian development. The reviewed elements have been divided into four groups: (a) metals of greatest toxicological significance (arsenic, cadmium, lead, mercury, and uranium) that are wide-spread in the human environment, (b) essential trace metals (chromium, cobalt, manganese, selenium, and zinc), (c) other metals with evident biological interest (nickel and vanadium), and (d) metals of pharmacological interest (aluminum, gallium, and lithium). A summary of the therapeutic use of chelating agents in the prevention of metal-induced developmental toxicity has also been included. meso-2,3-Dimercaptosuccinic acid (DMSA) and sodium 2,3-dimercaptopropane-1-sulfonate (DMPS) have been reported to be effective in alleviating arsenic- and mercury-induced teratogenesis, whereas sodium 4,5-dihydroxybenzene-1,3-disulfonate (Tiron) would protect against vanadium- and uranium-induced developmental toxicity.

Fetal detriment used as an index of effects of diethylene glycol on Syrian hamster fetuses

The effect of diethylene glycol (digol, diEG; specific gravity = 1.12) on the embryo was studied in the pregnant Syrian hamster at dosages from 2 1/4 to 4 ml/kg (2.52-4.48 g/kg). The hamsters were dosed by (single) intraperitoneal injection because previous experiments had indicated that oral dosing in the drinking water (and therefore possibly gavage dosing also) causes the hamsters to drink less. The digol was diluted with distilled water and injected on d 8 of pregnancy. Distilled water was used for the controls. At all dosages, fetuses from treated animals examined at autopsy on d 15 were found to be lighter than those from control animals. Abnormalities were seen at all dosages, mainly neural-tube defects (exencephaly, cranial bleb, and myelomeningocele). No neural-tube defects were observed in control animals. A dosage-related deficit in the number of live, externally nonmalformed fetuses was observed and was matched by a dosage-related increase in the number of live externally abnormal fetuses. Few dead full-term fetuses were found, but there was a dosage-related increase in the "late" resorption rate. A new summarizing measure, the fetal detriment (FD), the deficit from control expectations of live, nonmalformed litter mass per live litter, was found to be proportional to the square of the dose-rate D, the regression through the origin in this study being FD = (0.934 +/- 0.329)D2. The 50% attrition dosage, the AD50, was 2.90 ml/kg (3.25 g/kg) in the hamster, with 95% confidence interval 2.21-5.41 ml/kg (2.48-6.06 g/kg). Diethylene glycol in high dosage produces damage to the fetuses of pregnant Syrian hamsters. It is not known whether this is an indirect result of the maternal toxicity, which was observed even at the lowest dosage used, or is the effect of digol or of its metabolites on the conceptus.

Spontaneous abortions among women exposed to organic solvents

We investigated the association between medically diagnosed spontaneous abortions and occupational exposure to organic solvents. The study population was composed of women biologically monitored for solvents. The workers were classified into exposure categories on the basis of work description and the use of solvents as reported in the questionnaires, and on biological exposure measurements. The odds ratio of spontaneous abortion for solvent exposure, adjusted for potentially confounding factors, was significantly increased (2.2, 95% confidence interval [CI] = 1.2-4.1). The increase was most consistent among workers exposed to aliphatic hydrocarbons: the odds ratio for high exposure was 3.9 (95% CI = 1.1-14.2) and for exposed graphics workers 5.2 (95% CI = 1.3-20.8). The odds ratio was increased also among toluene-exposed shoe workers (9.3, 95% CI = 1.0-84.7). The results of the study support the hypothesis of a positive association between spontaneous abortion and exposure to organic solvents during pregnancy and suggest that exposure, especially to aliphatic hydrocarbons, increases the risk of abortion.

Induction of morphologically abnormal sperm in rats exposed to O-Xylene

An analysis of sperm abnormalities can be used as a rapid method to determine the mutagenic potential of chemical agents as well as the toxic potential of chemicals on the whole animal. O-Xylene was investigated for its potential mutagenicity by the sperm abnormality assay. Sprague Dawley rats 10-16 weeks old were injected intraperitoneally (ip) with 0.5 and 1.5 ml/kg body weight of o-xylene in corn oil. Five weeks after treatment, animals were sacrificed and sperm examined for morphological abnormalities. Several morphologically abnormal sperm types were observed; among these were those with amorphous heads, and banana-like heads. Animals housed at room temperatures of 20-24 degrees C showed no significant increase in abnormal sperm over the control. Rats housed at temperatures between 24 and 30 degrees C after ip injection with 0.5 ml/kg o-xylene showed a significant increase in abnormal sperm.

Embryotoxicity of industrial chemicals on the chicken embryo: dithiocarbamates

Seven dithiocarbamates and three acetates were tested for teratogenicity and lethality in three-day chicken embryos. These included: cadmium diethyldithiocarbamate (CdDE), zinc diethyldithiocarbamate (ZnDE), zinc ethylphenyldithiocarbamate (ZnEP), zinc dibutyldithiocarbamate (ZnDB), copper dimethyldithiocarbamate (CuDM), tellurium diethyldithiocarbamate (TeDE), and piperidine pentamethylenedithiocarbamate (PPM), cadmium acetate (CdAC), copper-(II)acetate (CuAC), and zinc acetate (ZnAC). The parameters measured were early deaths, recorded within two days of injection, late deaths of malformed embryos, late deaths of nonmalformed embryos, and malformed survivors. The order of embryotoxicity decreased as follows: CdAC greater than CdDE greater than ZnDE greater than or equal to ZnEP greater than or equal to ZnDB greater than CuDM greater than TeDE greater than CuAC greater than PPM greater than ZnAC. The only exception to this order was the relatively weak teratogenicity of the metal acetates as compared to dithiocarbamates. Cadmium and zinc dithiocarbamates were potent embryotoxic agents eliciting lethality and malformations at doses of 1 to 10 nmole per egg. Most embryonic deaths occurred at stages 29 to 31, and most of the dead embryos were malformed.