The Global Landscape of Occupational Exposure Limits--Implementation of Harmonization Principles to Guide Limit Selection.

Occupational exposure limits (OELs) serve as health-based benchmarks against which measured or estimated workplace exposures can be compared. In the years since the introduction of OELs to public health practice, both developed and developing countries have established processes for deriving, setting, and using OELs to protect workers exposed to hazardous chemicals. These processes vary widely, however, and have thus resulted in a confusing international landscape for identifying and applying such limits in workplaces. The occupational hygienist will encounter significant overlap in coverage among organizations for many chemicals, while other important chemicals have OELs developed by few, if any, organizations. Where multiple organizations have published an OEL, the derived value often varies considerably-reflecting differences in both risk policy and risk assessment methodology as well as access to available pertinent data. This article explores the underlying reasons for variability in OELs, and recommends the harmonization of risk-based methods used by OEL-deriving organizations. A framework is also proposed for the identification and systematic evaluation of OEL resources, which occupational hygienists can use to support risk characterization and risk management decisions in situations where multiple potentially relevant OELs exist.

Information dissemination and use: critical components in occupational safety and health.

BACKGROUND: Information dissemination is a mandated, but understudied, requirement of occupational and environmental health laws and voluntary initiatives. Research is needed on the factors that enhance and limit the development, transfer, and use of occupational safety and health information (OSH). Contemporary changes in the workforce, workplaces, and the nature of work will require new emphasis on the dissemination of information to foster prevention. METHODS: Legislative and regulatory requirements and voluntary initiatives for dissemination of OSH information were identified and assessed. Literature on information dissemination was reviewed to identify important issues and useful approaches. RESULTS: More than 20 sections of laws and regulations were identified that mandated dissemination of occupational and environmental safety and health information. A four-stage approach for tracking dissemination and considering the flow of information was delineated. Special areas of dissemination were identified: the information needs of the changing workforce, new and young workers; small businesses; and workers with difficulty in understanding or reading English. CONCLUSIONS: We offer a framework for dissemination of OSH information and underscore the need to focus on the extent to which decision-makers and others receive and use such information. More solid data are also needed on current investments in disseminating, diffusing and applying OSH information and on the utility of that information. Am. J. Ind. Med. 44:515-531, 2003. Published 2003 Wiley-Liss, Inc.

In vivo percutaneous absorption studies of volatile organic solvents in hairless mice. II. Toluene, ethylbenzene and aniline.

Percutaneous absorption studies were conducted with three single-ring, radiolabeled aromatic solvents (benzene derivatives) using a recently described direct method for studying volatile chemicals in hairless mice. Total absorption, determined from the sums of radioactivity found in the excreta, expired breath and carcass, was 2.1+, 3.4% and 4.7% of the nominal dose for toluene, ethylbenzene and aniline, respectively. Breath decay curves indicated that absorption of toluene and ethylbenzene was complete by 15 min after application and that by this time the excretion rate of aniline exceeded the absorption rate. Evaporation rates were used to derive estimated contact times, and these in turn were used in conjunction with the absorbed doses to estimate percutaneous absorption rates. Equivalent dermal exposures (cm2.min) that would yield body burdens equivalent to those expected following 8-h inhalations at existing US permissible exposure limits during light work were calculated. The data indicate that dermal absorption of these compounds could approach or exceed that from inhalation under some work conditions. Correlations between absorption and various physical properties were evaluated using Spearman's correlation coefficients. The physical properties evaluated included volatility, solubility, octanol/water partition coefficients and melting points. For this limited series of benzene derivatives, two measures of volatility, i.e. vapor pressure and boiling point, were the only physical properties significantly correlated with percutaneous absorption.

Occupational safety and health standards.

If we are to approach developing a safe and healthful workplace in a more timely fashion, a more generic approach must be considered and applied instead of developing recommendations and standards simply on a substance-by-substance basis, an approach that has been the most prominent. Some examples in which developing generic standards may be appropriate are: cholinesterase-inhibiting substances, neurotoxic agents, reproductive hazards, cold environments, and vibration syndrome, to name but a few. It is important to recognize that developing standards based on individual substances often does not allow for the role of synergism, a reaction that has had little study, but it is important in controlling occupational disease and injury. These concerns can be addressed in several ways. One is to look at processes or conditions found in the workplace; for example, coke oven emissions that OSHA has promulgated into a standard and, as NIOSH has done in their recommendations to OSHA for foundries, coal tar products, the manufacture of paint and allied coatings, field sanitation, hazardous waste management, hot environments, and confined spaces. Another is to address groups of similar substances such as NIOSH has done with alkanes, benzidine-based dyes, diisocyanates, dinitrotoluenes, and glycol ethers. A third comprehensive approach is to look at general categories of hazards, such as the generic carcinogen policy, and the hazard communication rule. Finally, risk must be considered in the development of any standard. Nelson Rockefeller once said in relation to an incidence involving a radiation hazard that, "you can't have a riskless society." I would amend this to say that you cannot have a reckless society either. Safety and health regulations are essential and must be designed, promulgated, and then enforced so that a reckless society is avoided or controlled, with a riskless society being the ultimate aim.

Interlaboratory studies with the Chinese hamster V79 cell metabolic cooperation assay to detect tumor-promoting agents.

Three laboratories participated in an interlaboratory study to evaluate the usefulness of the Chinese hamster V79 cell metabolic cooperation assay to predict the tumor-promoting activity of selected chemicals. Twenty-three chemicals of different chemical structures (phorbol esters, barbiturates, phenols, artificial sweeteners, alkanes, and peroxides) were chosen for testing based on in vivo promotion activities, as reported in the literature. Assay protocols and materials were standardized, and the chemicals were coded to facilitate unbiased evaluation. A chemical was tested only once in each laboratory, with one of the three laboratories testing only 15 out of 23 chemicals. Dunnett's test was used for statistical analysis, and differences between treated- and control-cell responses were analyzed at P less than or equal to .01. Chemicals were scored as positive (at least two concentration levels statistically different than control), equivocal (only one concentration statistically different), or negative. For 15 chemicals tested in all three laboratories, there was complete agreement among the laboratories for nine chemicals. For the 23 chemicals tested in only two laboratories, there was agreement on 16 chemicals. With the exception of the peroxides and alkanes, the metabolic cooperation data were in general agreement with in vivo data. However, an overall evaluation of the V79 cell system for predicting in vivo promotion activity was difficult because of the organ specificity of certain chemicals and/or the limited number of adequately tested nonpromoting chemicals.

Calcium homeostasis in pregnant rats treated with ethylene glycol monomethyl ether (EGME).

The industrial solvent ethylene glycol monomethyl ether (EGME) is a known teratogen that has been reported to alter calcium metabolism in guinea pigs during chronic exposure. Because of the tremendous demand of reproduction on maternal calcium stores, the effects of EGME on calcium and vitamin D metabolism during gestation were examined. Timed pregnant rats were treated by gavage with 0, 50, or 100 mg/kg EGME in 10 ml/kg distilled water on Days 9-15 of gestation (sperm = Day 1) and examined on Days 16 and 21. Virgin rats were treated for 7 days with 0 or 100 mg/kg EGME and examined 5 days later. EGME exposure did not affect body or kidney weight in virgin or pregnant rats, but liver weight was reduced in near-term pregnant rats treated with 100 mg/kg EGME. EGME (50 mg/kg) reduced litter size and fetal body weight and caused a significant number of live fetuses to have visceral abnormalities. EGME (100 mg/kg) caused all fetuses to be resorbed. In nonpregnant rats, 100 mg/kg did not affect serum 1,25-dihydroxyvitamin D (1,25(OH)2D3), 25-hydroxyvitamin D, ionic calcium, total calcium, or parathyroid hormone. EGME appeared to have a dose-dependent effect on calcium and vitamin D metabolism during gestation. On Day 21 of gestation, total calcium and ionic calcium were increased and 1,25(OH)2D3 was reduced in rats treated with EGME compared with nontreated controls. However, significant alterations in calcium homeostasis were evident only in dams that completely resorbed their litters. The changes in calcium and vitamin D metabolism during gestation appear to be secondary to the EGME-induced loss of litters.

Reproductive toxicology of inhaled styrene oxide in rats and rabbits.

Experiments were performed to evaluate reproductive and developmental toxicology in rats and rabbits exposed to styrene oxide by inhalation. Female rats were exposed to 100 or 300 ppm styrene oxide or to filtered air for 7 h/day, 5 days/week for 3 weeks. Extensive mortality occurred in rats that received prolonged exposure to 100 ppm styrene oxide while 300 ppm was rapidly lethal. As a result exposures were terminated in this latter group and the group was eliminated from further study. The rats of the 0 and 100 ppm groups were then mated and exposed to 0 or 100 ppm styrene oxide daily through 18 days of gestation (dg). Female rabbits were artificially inseminated and exposed for 7 h daily to 0, 15, or 50 ppm styrene oxide through 24 dg. Both of these lower concentrations used for exposure of the rabbits produced mortality of does. The rats were killed at 20 dg and the rabbits at 30 dg. Pregnant animals were examined for toxic changes including altered tissue weights and histopathologic effects. Litters were evaluated using several measures of embryotoxicity, and live fetuses were examined for external, visceral, and skeletal malformations. Exposure during gestation appeared to increase preimplantation loss in rats, and tended to increase the incidence of resorptions in rabbits. In both species, fetal weights and crown-rump lengths were reduced by gestational exposure. The incidences of ossification defects of the sternebrae aned occipital bones were increased by gestational exposure of rats to styrene oxide. These results indicate that inhalation exposures at these concentrations produce reproductive and development toxicity, as well as maternal toxicity.

In vivo percutaneous absorption studies of volatile solvents in hairless mice. I. Description of a skin-depot.

A stainless-steel skin-depot is discussed that may be used during short-term studies to measure directly percutaneous absorption of radiolabeled, volatile chemicals through the skin of unanesthetized, unrestrained hairless mice. The skin-depot is glued to the backs of the mice using cyanoacrylate glue. The top portion of the depot contains activated charcoal (or other sorbent) to capture for analysis the portion of the test chemical which normally evaporates from the treatment site. This allows the use of metabolism cages for the capture of expired breath, as well as urine and feces. Thus, dermal absorption of the test chemical can be summed directly from the radioactivity found in excreta (urine and feces), the animal carcass (including the skin treatment site) and expired breath.

Percutaneous penetration of benzene in hairless mice: an estimate of dermal absorption during tire-building operations.

Repeated skin contact with solvents containing as much as 0.5% benzene is common in workers building regular bias passenger tires. To estimate the amount of benzene absorbed through the skin of these workers, a series of in vivo studies was conducted in hairless mice. Percutaneous absorption, following single dermal applications of 14C-benzene contained in rubber solvent at a concentration of 0.5% (v/v), was calculated directly from the sums of radioactivity found in excreta, expired breath, and the carcass. Data from the study, together with observations made during tire-building operations, suggest that a worker could absorb 4-8 mg of benzene daily through the skin. This compares to 14 mg per day via inhalation at the NIOSH recommended standard of 1 ppm. Thus dermal absorption could contribute from 20-40% of the total benzene dose of these workers.

The pharmacokinetics of benzo[alpha]pyrene in the isolated perfused rabbit lung: the influence of benzo[alpha]pyrene, n-dodecane, particulate, or sulfur dioxide.

The pharmacokinetics of benzo[a]pyrene (BaP) in the isolated perfused rabbit lung (IPL) following pretreatment of the whole animal or simultaneous administration to the IPL with n-dodecane, ferric oxide, crude airborne particulate (CAP), fly ash or sulfur dioxide have been investigated using a one compartment model. The rate constant for the appearance (ka) of BaP in the blood, the clearance of BaP from the blood, and the rate of appearance of BaP metabolites (RAM) were the kinetic parameters determined. BaP entered the blood rapidly with an average half-life of 11 min in experiments in which the IPLs received only BaP on perfusion. The logarithms of the clearances from these experiments were linearly correlated with the RAMs. In these experiments, pretreatment of the whole animal with BaP produced a 48-55-fold increase in BaP clearance while pretreatment with n-dodecane increased the clearance 4-fold in comparison with no pretreatment. Pretreatment with ferric oxide or ferric oxide and BaP increased the clearance by factors of 5.5 and 1.5, respectively, over those of unpretreated and BaP pretreated experiments.

Effects of ethylene glycol monomethyl (EGME) and monoethyl (EGEE) ethers on the immunocompetence of allogeneic and syngeneic mice bearing L1210 mouse leukemia.

The effect of ethylene glycol monomethyl ether (EGME) and ethylene glycol monoethyl ether (EGEE) on cell-mediated immunity was evaluated by an allograft rejection assay. Allogeneic B6C3F1 (C57BL/6 X C3H) mice were given oral doses of 600, 1200, or 2400 mg/kg/administration of EGEE or 300, 600, 1200 mg/kg/administration of EGME on days -12 through -8 or cyclophosphamide (Cy) at 180 mg/kg by the IP route on day -1. Untreated controls were given oral doses of water on days -12 through -8 and -5 through -1. On day 0, the mice were challenged with 1 X 10(2), 3 X 10(3), and 1 X 10(5) or 3 X 10(6) L1210 cells by the IP route. Syngeneic CD2F1 (Balb/c X DBA/2) mice were challenged with 1 X 10(5) L1210 cells on day 0 and were treated on days 1 to 5 and 8 to 12 with the same dosages of EGME and EGEE used for the B6C3F1 mice. Water-treated syngeneic mice died with a median survival time (MST) of 8.0 days. There was no effect on the MST of syngeneic mice treated with either EGME or EGEE, indicating no direct antitumor effect of the compounds. All allogeneic mice receiving either water or Cy and challenged with 3 X 10(6) tumor cells, died with ascites. However, when mice were treated with EGME or EGEE and challenged with 3 X 10(6) tumor cells, no more than one animal per group died. This would indicate that there was a prophylactic action of the compounds or that the immune system was stimulated. Blood smears of allogeneic mice were made for differential counts the last day of drug dosing, the day of death where possible, and on survivors at day 43 post-tumor implantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Results of testing fifteen glycol ethers in a short-term in vivo reproductive toxicity assay.

Fifteen glycol ethers were investigated for their potential to cause adverse reproductive toxic effects using an in vivo mouse screening bioassay. Pregnant mice were orally dosed once per day on days 7 through 14 of gestation at concentrations causing 0 to 41% maternal mortality. Reproductive endpoints included pup survival in utero (percent of live litters/pregnant survivors), pup perinatal and postnatal survival (number of live pups per litter, number of dead pups per litter, and pup survival to 2.5 days of age), and pup body weight statistics (weight at birth and weight at 2.5 days of age). The study was conducted in two phases: a dose range-finding phase using nonpregnant female mice, and a definitive reproductive phase using time-mated mice. The range-finding phase sought to identify, for each chemical, the maternal LD10 as the target dose. However, based upon reproductive phase results, such an exact dose was impractical to achieve. Thus, a range from the LD5 to the LD20 was considered a sufficient challenge dose that would not affect results due to high mortality, i.e., greater than the LD20. Glycol ethers were assigned to groups having different priorities for further testing based upon whether a sufficient challenge dose was administered and the degree of effects recorded for each chemical.(ABSTRACT TRUNCATED AT 250 WORDS)

The isolated perfused lung.

The unique nonrespiratory functions of the lungs have become more apparent in recent years. The isolated perfused lung model offers many advantages over other methods for the study of pulmonary metabolism, xenobiotic disposition and the influence of interactions among agents of different physical forms. Detailed descriptions of the experimental preparation are elements in evaluating and comparing data from various sources but these are frequently neglected. A discussion and critique of the following elements are provided in this review in order to elucidate the typical problems one might encounter in evaluating data: perfusate type, perfusion method, construction materials, ventilation method, temperature control, surgical procedure, microbiological contamination and evaluation criteria of the preparation. Examples are given where the IPL method has been applied and suggestions are made for future research efforts.

The effects of a cocarcinogen, ferric oxide, on the metabolism of benzo[a]pyrene in the isolated perfused lung.

An isolated perfused New Zealand rabbit lung preparation was used to investigate the effects of a cocarcinogen, ferric oxide (Fe2O3), on the metabolism of benzo[a]pyrene (BaP), a ubiquitous potent carcinogen that has been associated with the increased incidence of human bronchiogenic carcinoma in occupational and urban settings. [14C]-BaP was administered intratracheally to an isolated perfused lung (IPL) preparation with and without Fe2O3 after intraperitoneal pretreatment of the whole animal with BaP or intratracheal pretreatment of the whole animal with Fe2O3 and/or BaP. BaP and its metabolites were isolated from serial blood samples up to 180 min after administration of [14C]BaP to the IPL. BaP and its metabolites were also isolated from lung tissue, washout fluid, macrophage, and trachea bronchi at the end of the perfusion at 180 min. Patterns of BaP metabolites were determined by chromatographic techniques and liquid scintillation counting. Fe2O3 pretreatment to the whole animal or administration of Fe2O3 to the IPL altered BaP metabolism by the perfused lung. Fe2O3 pretreatment to the whole animal resulted in an increase in the total rate of appearance of metabolites of BaP in the blood (ng/g lung X h), while Fe2O3 administration to the IPL resulted in a decrease in the total rate of appearance of BaP metabolites in the blood and inhibited the effect of pretreatment. Administration of Fe2O3 with BaP to the IPL with or without Fe2O3 pretreatment to the whole animal, or BaP administration to the IPL preceded by Fe2O3 pretreatment to the whole animal, enhanced dihydrodiol formation and depressed formation of water-soluble metabolites. Since dihydrodiol formation is considered to be the active pathway of BaP metabolism, these data suggest that pulmonary exposure to a known cocarcinogen, Fe2O3, in the presence of BaP results in increased production of dihydrodiols of BaP, which may be further metabolized to the ultimate carcinogenic form(s) of BaP. Therefore, Fe2O3 can enhance the metabolic activation of BaP by the lung, as well as act as a carrier for penetration and retention of BaP in the lung.

Genetic effects of 2-methoxyethanol and bis(2-methoxyethyl)ether.

2-Methoxyethanol and bis(2-methoxyethyl)ether were subjected to the following assays for genetic toxicity: Ames' test, unscheduled DNA synthesis (UDS) assay in human embryo fibroblasts, sex-linked recessive lethal (SLRL) test in Drosophila, dominant lethal test in male rats, bone marrow metaphase analysis in male and female rats, and the sperm abnormality test in mice. In vivo test animals were exposed to atmospheric concentrations of 25 or 500 ppm 2-methoxyethanol and 250 or 1000 ppm bis(2-methoxyethyl)ether. Point mutations in Ames' test and UDS in fibroblasts were not increased by either compound, while the SLRL test gave ambiguous results which deserve further investigation. Chromosomal aberration frequencies were not increased in rat bone marrow, but there was evidence from the dominant lethal tests that both compounds have profound effects upon male rat fertility during the meiotic phase. Pregnancy frequency was greatly reduced and preimplantation losses were large. In addition, there was evidence of postimplantation losses. Sperm abnormalities were increased in mice exposed to both compounds, but particularly bis(2-methoxyethyl)ether. These effects on male reproductive cells were confined to the higher concentrations of both compounds. It was concluded that the weak mutagenic and particularly the strong antifertility effects described here are important for the safety evaluation of these ethylene glycol ethers.

Evaluation of propylene oxide for mutagenic activity in 3 in vivo test systems.

Propylene oxide (CAS No. 75-56-9) was tested for mutagenic activity following vapor exposure using 3 in vivo test systems. Rat dominant lethal and mouse sperm-head morphology assays were conducted using males exposed to propylene oxide at 300 ppm in a dynamic exposure chamber for 7 h per day on 5 consecutive days. A sex-linked recessive lethal test in Drosophila melanogaster employed a 24-h static exposure to propylene oxide at 645 ppm. Male mice were killed 1, 3, 5, 7, and 9 weeks post-exposure for evaluation of sperm-head morphology. Propylene oxide exposure did not result in an increase in abnormal forms. Male rats were mated with 2 virgin females per week for 6 weeks following exposure. A statistically significant increase in preimplantation losses and a statistically significant reduction in the number of living implants in the first post-exposure week did not appear to be treatment related. A highly significant increase in sex-linked recessive lethal mutations was observed in two germ cell stages (mature sperm and developing spermatocytes). These results warrant continued caution in potential human exposure to propylene oxide.

Influence of airborne particulate on the metabolism of benzo[a]pyrene in the isolated perfused lung.

Benzo[a]pyrene (BaP), a ubiquitous potent carcinogen, has been associated with the increased incidence of human bronchiogenic carcinoma in occupational and urban settings. A detailed knowledge of the rate and pattern of metabolite formation and factors affecting their formation is essential for understanding the mechanism of action of BaP in the lung. An isolated perfused New Zealand rabbit lung preparation was used to investigate the effects of a crude airborne particulate mixture on the metabolism of BaP. [14C]BaP with and without crude air particulate (CAP) was administered intratracheally to an isolated perfused lung (IPL) preparation after intratracheal pretreatment of the whole animal with CAP and/or BaP, or intraperitoneal pretreatment of the whole animal with BaP. BaP and its metabolites were extracted from perfusing blood at 6 time points up to 180 min after administration of [14C]BaP to the IPL. BaP and its metabolites were also extracted from lung tissue, washout fluid, aveolar macrophages, and trachea bronchi at the end of the perfusion at 180 min. Patterns of BaP metabolites were determined by chromatographic techniques and liquid scintillation counting. Particulate pretreatment of the whole animal or administration of the particulate to the IPL altered BaP metabolism by the perfusing lung. Particulate pretreatment of the whole animal resulted in increases in the total rates of appearance of metabolites of BaP in the blood (ng/g lung . h), while particulate administration to the IPL resulted in decreases in the total rate of appearance of metabolites of BaP in the blood and negated the effects of pretreatments. Coadministration of particulate with BaP to the IPL with and without particulate pretreatment of the whole animal, or BaP administration to the IPL preceded by particulate pretreatment of the whole animal, enhanced dihydrodiol formation and depressed formation of water-soluble materials. This is important because dihydrodiol formation is considered part of the active pathway of BaP carcinogenicity. These data suggest that pulmonary particulate exposure in the presence of BaP results in the initial increased production of dihydrodiols of BaP that may be further metabolized to compounds believed to be the ultimate carcinogenic form(s) of BaP.

Reproductive-toxicologic assessment of the epoxides ethylene oxide, propylene oxide, butylene oxide, and styrene oxide.

Ethylene oxide (CAS no 75-21-8), propylene oxide (CAS no 75-56-9), butylene oxide (CAS no 106-88-7), and styrene oxide (CAS no 96-09-3) were tested for teratogenic activity by inhalation exposure of rats and rabbits. Ethylene oxide and propylene oxide were tested at only one concentration in both species (150 ppm for ethylene oxide and 500 ppm for propylene oxide). Butylene oxide was tested at 250 and 1,000 ppm in both species, while styrene oxide was tested at 100 ppm in rats and 15 and 50 ppm in rabbits. For each of these four epoxides, the acute toxicity was similar for pregnant and nonpregnant rats. Styrene oxide was the most toxic in both species, and rabbits were more sensitive than rats. Rats exposed to propylene oxide for 7 h/d, 5 d/week for three weeks before breeding had a significant reduction in the number of corpora lutea. Fetal mortality was not increased, but significantly fewer mated rats were found pregnant following gestational exposure to styrene oxide, a finding suggesting preimplantation loss. In rabbits exposed to styrene oxide, the number of resorptions per litter was increased in concentration related manner, but differences were not statistically significant. Fetal examination revealed evidence of fetotoxicity with all four epoxides. There was no overt teratogenic activity, but a number of minor morphologic aberrations were detected.

Drosophila as a tool for the rapid assessment of chemicals for teratogenicity.

Drosophila melanogaster is being investigated for its potential to aid in identifying priority chemicals for teratologic study. The method encompasses treating larvae over the entire metamorphosis period, i.e., from the egg through three instar stages to pupa formation, by incorporating the test chemical into the medium. Adult flies are systematically examined under a binocular microscope for external morphological anomalies. Data from treated flies can be compared with those from concurrent control flies using standard statistical tests. Results from this developmental work reveal a dramatic and reproducible response of Drosophila to various chemical treatments. Validation studies, testing known teratogens and nonteratogens, are necessary before such a system can be incorporated into existing teratologic screening regimens.

Teratogenicity of 2-ethoxyethanol by dermal application.

Undiluted 2-ethoxyethanol or water (control) was applied to the skin of pregnant Sprague-Dawley rats on days 7--16 of gestation (sperm = day 1). Applications were made 4 times daily in volumes of 0.25 or 0.50 ml 2-ethoxyethanol. Females exhibited ataxia following treatment of the high-dose group, and weight gain was significantly (p less than u. 0.001) reduced in the last half of gestation. Litters were collected by caesarian section on day 21 of gestation, and fetuses were examined for external defects. Half of the fetuses were cleared and stained in alizarin red S for skeletal examinations, and half were examined for visceral defects by the Wilson technique. Intrauterine death was 100% in the high-dose group. In the lower dosage group, there was a significant increase in the number of pregnant females with 100% dead implants (p less than 0.001), a significant reduction in the number of live fetuses per litter (p less than 0.001), a significant reduction in fetal body weight (p less than 0.001), and a significant increase in the incidence of skeletal variations (p less than 0.05) and cardiovascular malformations (p less than 0.05).