Occupational and environmental risks in and around a smelter in northern Sweden. III. Frequencies of spontaneous abortion

Ambient temperature and stillbirth risks in northern Sweden, 1880-1950

Background

Climate vulnerability of the unborn can contribute to adverse birth outcomes, in particular, but it is still not well understood. We investigated the association between ambient temperature and stillbirth risk among a historical population in northern Sweden (1880-1950).

Methods

We used digitized parish records and daily temperature data from the study region covering coastal and inland communities some 600 km north of Stockholm, Sweden. The data included 141,880 births, and 3,217 stillbirths, corresponding to a stillbirth rate of 22.7 (1880-1950). The association between lagged temperature (0-7 days before birth) and stillbirths was estimated using a time-stratified case-crossover design. Incidence risk ratios (IRR) with 95% confidence intervals were computed, and stratified by season and sex.

Results

We observed that the stillbirth risk increased both at low and high temperatures during the extended summer season (April to September), at -10°C, and the IRR was 2.3 (CI 1.28, 4.00) compared to the minimum mortality temperature of +15°C. No clear effect of temperature during the extended winter season (October to March) was found. Climate vulnerability was greater among the male fetus compared to the female counterparts.

Conclusion

In this subarctic setting before and during industrialization, both heat and cold during the warmer season increased the stillbirth risk. Urbanization and socio-economic development might have contributed to an uneven decline in climate vulnerability of the unborn.

Obstetric Outcomes in West Cumberland Hospital: Is There a Risk from Sellafield?

A retrospective study was made of the obstetric outcome of 18,252 babies born in West Cumberland Hospital in the years 1975 to 1985. There were 934 premature births (before 37 weeks), 555 small for dates births (under 2.5 kg but not before 37 weeks), 167 stillbirths, 125 neonatal deaths and 236 reported congenital malformations. The 212 babies born to mothers from Seascale during that time were compared with the births to mothers from other areas in West Cumbria Health District in order to assess any adverse effect from possible radioactive discharge at nearby Sellafield. There was no evidence of any increased incidence of these outcomes in Seascale births. Adequate retrospective data on miscarriage rates were not available, but using indirect information on hospital inpatients, no statistically significant increased incidence was found, although the absolute numbers of miscarriage in Seascale were slightly higher than expected. From this evidence, no adverse effects on completed pregnancies can be attributed to the Sellafield plant of British Nuclear Fuels. However, a prospective study of miscarriage incidence in West Cumbria and near other nuclear installations is urgently needed.

Appropriate Exposure Routes and Doses in Studies Designed to Assess Developmental Toxicity: A Case Study of Inorganic Arsenic

Assessment of risks to human health from chemical agents is a complex process that requires the assembly, careful analysis, and integration of human and animal data collected from studies performed at different times, for disparate purposes, and under varying conditions. The application of risk assessment methods to data without consideration of the relevance of critical experimental parameters such as route of exposure or magnitude of dose can lead to specious determinations of the risk posed by exposure to environmental agents. A case study of the purported risk of developmental toxicity from inorganic arsenic is presented to illustrate (1) the nature of the problem, (2) how extant data from all studies are useful, (3) how appropriately designed modern studies can clarify the situation, and (4) how conflicted data should be evaluated in terms of appropriateness for use in risk assessment.

Association between chronic arsenic exposure and nutritional status among the women of child bearing age: a case-control study in Bangladesh

The role of nutritional factors in arsenic metabolism and toxicity is yet to be fully elucidated. A low protein diet results in decreased excretion of DMA and increased tissue retention of arsenic in experimental studies. Malnourished women carry a higher risk of adverse pregnancy outcomes. Chronic exposure to high arsenic (>50 microg/L) through drinking water also increases the risk of adverse pregnancy outcomes. The synergistic effects (if any) of malnutrition and chronic arsenic exposure may worsen the adverse pregnancy outcomes. This population based case control study reports the association between chronic arsenic exposure and nutritional status among the rural women in Bangladesh. 348 cases (BMI < 18.5) and 360 controls (BMI 18.5-24.99) were recruited from a baseline survey conducted among 2,341 women. An excess risk for malnutrition was observed among the participants chronically exposed to higher concentrations of arsenic in drinking water after adjusting for potential confounders such as participant's age, religion, education, monthly household income and history of oral contraceptive pills. Women exposed to arsenic >50 microg/L were at 1.9 times (Odds Ratio = 1.9, 95% CI = 1.1-3.6) increased risk of malnutrition compared to unexposed. The findings of this study suggest that chronic arsenic exposure is likely to contribute to poor nutritional status among women of 20-45 years.

Murshidabad—One of the Nine Groundwater Arsenic-Affected Districts of West Bengal, India. Part II: Dermatological, Neurological, and Obstetric Findings

INTRODUCTION

To understand the severity of related health effects of chronic arsenic exposure in West Bengal, a detailed 3-year study was carried out in Murshidabad, one of the nine arsenic-affected districts in West Bengal.

METHODS

We screened 25,274 people from 139 arsenic-affected villages in Murshidabad to identify patients suffering from chronic arsenic toxicity for evidence of multisystemic features and collected biological samples such as head hair, nail, and spot urine from the patients along with the tubewell water they were consuming.

RESULTS

Out of 25,274 people screened, 4813 (19%) were registered with arsenical skin lesions. A case series involving arsenical skin lesions resulting in cancer and gangrene were noted during this study. Representative histopathological pictures of skin biopsy of different types of lesions were also presented. Out of 2595 children we examined for arsenical skin lesions, 122 (4%) were registered with arsenical skin lesions, melanosis with or without keratosis. Different clinical and electrophysiological neurological features were noticed among the arsenic-affected villagers. Both the arsenic content in the drinking water and duration of exposure may be responsible in increasing the susceptibility of pregnant women to spontaneous abortions, stillbirths, preterm births, low birth weights, and neonatal deaths. Some additional multisystemic features such as weakness and lethargy, chronic respiratory problems, gastrointestinal symptoms, and anemia were also recorded in the affected population.

DISCUSSION

The findings from this survey on different health effects of arsenic exposure were compared to those from previous studies carried out on arsenic-affected populations in India and Bangladesh as well as other affected countries.

CONCLUSION

Multisystemic disorders, including dermal effects, neurological complications, and adverse obstetric outcomes, were observed to be associated with chronic arsenic exposure in the study population in Murshidabad, West Bengal. The magnitude of severity was related to the concentration of arsenic in water as well as duration of the exposure.

Chronic Arsenic Exposure and Adverse Pregnancy Outcomes in Bangladesh

BACKGROUND

Chronic exposure to arsenic through drinking water has the potential to cause adverse pregnancy outcomes, although the association has not been demonstrated conclusively. This cross-sectional study assessed the association between arsenic in drinking water and spontaneous abortion, stillbirth, and neonatal death.

METHODS

In this cross-sectional study, 533 women were interviewed. Information on sociodemographic characteristics, drinking water use, and adverse pregnancy outcomes was obtained through a structured pretested interviewer-administered questionnaire. The respondents reported use of a total of 223 tube wells; for 208 wells, water samples were measured using an ultraviolet/visible spectrophotometry method, whereas 15 were measured by flow-injection hydride generation atomic absorption spectrometry (FIHG-AAS).

RESULTS

Excess risks for spontaneous abortion and stillbirth were observed among the participants chronically exposed to higher concentrations of arsenic in drinking water after adjusting for participant's height, history of hypertension and diabetes, and (for neonatal death only) age at first pregnancy. Comparing exposure to arsenic concentration of greater than 50 microg/L with 50 microg/L or less, the odds ratios were 2.5 (95% confidence interval=1.5-4.3) for spontaneous abortion, 2.5 (1.3-4.9) for stillbirth, and 1.8 (0.9-3.6) for neonatal death.

CONCLUSIONS

These study findings suggest that chronic arsenic exposure may increase the risk of fetal and infant death.

Carcinogenic and systemic health effects associated with arsenic exposure--a critical review

Arsenic and arsenic containing compounds are human carcinogens. Exposure to arsenic occurs occupationally in several industries, including mining, pesticide, pharmaceutical, glass and microelectronics, as well as environmentally from both industrial and natural sources. Inhalation is the principal route of arsenic exposure in occupational settings, while ingestion of contaminated drinking water is the predominant source of significant environmental exposure globally. Drinking water contamination by arsenic remains a major public health problem. Acute and chronic arsenic exposure via drinking water has been reported in many countries of the world, where a large proportion of drinking water is contaminated with high concentrations of arsenic. General health effects that are associated with arsenic exposure include cardiovascular and peripheral vascular disease, developmental anomalies, neurologic and neurobehavioural disorders, diabetes, hearing loss, portal fibrosis, hematologic disorders (anemia, leukopenia and eosinophilia) and multiple cancers: significantly higher standardized mortality rates and cumulative mortality rates for cancers of the skin, lung, liver, urinary bladder, kidney, and colon in many areas of arsenic pollution. Although several epidemiological studies have documented the sources of exposure and the global impact of arsenic contamination, the mechanisms by which arsenic induces health effects, including cancer, are not well characterized. Further research is needed to provide a better understanding of the pathobiology of arsenic-induced diseases and to better define the toxicologic pathology of arsenic in various organ systems. In this review, we provide and discuss the underlying pathology and nature of arsenic-induced lesions. Such information is critical for understanding the magnitude of health effects associated with arsenic exposure throughout the world.

Arsenic exposure from drinking water and birth weight

BACKGROUND

Arsenic exposures from drinking water increase the risk of various cancers and noncancer health endpoints. Limited evidence suggests that arsenic may have adverse human reproductive effects. We investigated the association between drinking water arsenic exposure and fetal growth, as manifest in birth weight.

METHODS

We conducted a prospective cohort study in two Chilean cities with contrasting drinking water arsenic levels: Antofagasta (40 micro g/L) and Valparaíso (<1 micro g/L). Study subjects completed in-depth interviews and provided urine samples for exposure analysis. We obtained pregnancy and birth information from medical records. The birth weight analysis was restricted to liveborn, singleton infants born between December 1998 and February 2000.

RESULTS

The final study group consisted of 424 infants from Antofagasta and 420 from Valparaíso. After controlling for confounders, results of the multivariable analysis indicated that Antofagasta infants had lower mean birth weight (-57 g; 95% confidence interval = -123 to 9).

CONCLUSION

This study suggests that moderate arsenic exposures from drinking water (<50 micro g/L) during pregnancy are associated with reduction in birth weight, similar in magnitude to that resulting from other environmental exposures such as environmental tobacco smoke and benzene.

Arsenic in drinking water and adverse pregnancy outcome in an arseniasis-endemic area in northeastern Taiwan

The well water in Lanyang Basin, which is located in the northeastern portion of Taiwan island, was found to have high levels of arsenic ranging from undetectable levels (<0.15 ppb) to 3.59 ppm. We performed a study to compare the risk of adverse pregnancy outcomes (preterm delivery and birthweight) between an area with historic high well water arsenic levels (arsenic-exposed area (AE)) and a comparison area with no historic evidence of arsenic water contamination (non-arsenic-exposed area (NAE)). The mean birth weight in the AEs and NAEs were 3132.6 and 3162.6 g, respectively. Babies born in AEs were on average 30 g lighter than those born in NAEs. AEs had a higher rate of preterm delivery than NAEs (3.74% vs 3.43%). The results of this study suggest that, after adjustment for potential confounders, arsenic exposure from drinking well water was associated, although not significantly, with the risk of preterm delivery, with an odds ratio of 1.10 (0.91-1.33). The estimated reduction in birth weight was 29.05 g (95% CI=13.55-44.55). The findings from this investigation provide evidence for a potential role for arsenic exposure through drinking water in increasing the risk of low birthweight.

[Cytotoxic effects of lead on the endocrine and exocrine sexual function of pubescent male and female rats. Demonstration of apoptotic activity]

This study deals with the impact of chronic exposure to lead on male and female fertility in rats. Male and female rats (3 months old) were fed on commercial tablets (SICO, Sfax). For drinking, some rats were given distilled water (T = controls), the other ones were given distilled water enriched with lead acetate, either 3 (P1 group) or 6 mg ml-1 (P2 group), for 15, 30, 45, 60 or 90 days. In male rats, absolute and relative weights of testis, epididymis, prostate and seminal vesicles were found to significantly decrease at day 15 in the P2 group and at day 45 in the P1 group. However, at day 60, these absolute and relative weights returned to control values. Lead-induced pathological changes in spermatogenesis were observed at day 15 by histological study: arrest of cell germ maturation, changes in the Sertoli cells, and presence of apoptotic cells revealed by borated toluidine blue in the testis. Presence of lead deposits was observed after histochemical staining using sodium rhodizonate. Serum testosterone level was found to be lowered at day 15 in both (P1) and (P2) groups, to display a peak at day 60, then to return to controls values, in spite of the continuation of the treatment. In female rats, absolute and relative weights of ovary and uterus were found unchanged. The vaginal smears practiced in females revealed the oestrus phase in all groups. Exposed females were mated with control males, and fecundity was assessed 15 days later by counting the number of pregnancies and the number of concepti per pregnancy. Fertility was found to be reduced in females of P1 and P2 groups as compared to control females (T group). Lead level in blood was found to be poorly correlated with the level of poisoning, whereas lead accumulation in tail was found to be dose-dependent. Therefore, lead accumulation in tail appears as a more reliable biomarker of exposure to lead. In summary, our study shows that chronic exposure to lead causes a double sexual disorder in rats: first, disorder deals with the hormonal function, which is affected at the early stages of poisoning, but is rapidly corrected; second, disorder deals with the genital tract, affecting the testis and the ovary, resulting in a reduced fertility in both P1 and P2 females, in spite of the presence of a normal oestrus. The cytotoxic effect of lead in males seems to be related to an apoptotic process.

Teratogen update: inorganic arsenic

BACKGROUND

Inorganic arsenic has been used by many laboratories to study the pathogenesis of exencephaly in rodents. These studies, which used predominantly injection exposures, coupled with the paucity of epidemiology data, resulted in the erroneous inference that inorganic arsenic should be considered a human teratogen.

METHODS

This study assembles and assesses literature analyses of older human and animal investigations together with the results of new experimental studies. These recent studies were performed according to modern regulatory guidelines, and relevant exposure routes (inhalation and ingestion) were used to evaluate the potential risk of developmental effects in humans.

RESULTS

The existing epidemiological data are inadequate to support risk assessment because of the failure to confirm or measure arsenic exposure during early gestation and the deficiencies in accounting for potential confounding factors. The animal data revealed that inorganic arsenic caused malformations in offspring only when it was injected into the veins or peritoneal cavity of pregnant animals during early gestation. Exposure via inhalation or oral ingestion, even at concentrations that were nearly fatal to pregnant females, caused no arsenic-related malformations.

CONCLUSIONS

Inorganic arsenic poses virtually no danger to developing offspring when maternal exposure occurs by relevant routes (oral and inhalation) at concentrations that are likely to be experienced in the environment or in the workplace.

The effect of lead on male fertility: a time to pregnancy (TTP) study

BACKGROUND

Growing attention has been paid in recent decades to the effects on male reproduction of occupational exposures to toxic agents. There is strong evidence that high level exposure to lead, i. e. blood lead level (PbB) > 70 microg/dl, is associated with male infertility and some reports suggest an effect even at lower PbB (i. e. < 50 microg/dl). The aim of this study is to shed more light on the postulated association between occupational exposure to relatively low levels of inorganic lead and reduced fertility in men estimated by the length of time taken to conceive: time to pregnancy (TTP).

METHODS

A survival analysis of TTP of the last pregnancy was performed adopting the Kaplan Meier methodology. The target population included 782 lead-exposed workers and 165 controls. 251 lead workers and 119 controls were finally eligible and interviewed. Lead-exposed subjects were distributed into four exposure levels according to their blood lead concentration (i.e. < 20; 20-29; 30-39, and >/= 40 microg/dl). The Cox model was adopted to estimate the Relative Risk of unsuccessful waiting time to pregnancy associated to the exposure to lead.

RESULTS

A statistically significant difference in fecundability (shorter TTP) in favor of exposed subjects was detected. Nevertheless, longer TTP was associated within the exposed group to higher levels of PbB, even though the gradient is not statistically significant. The exposed workers revealed an average number of children larger than those not exposed, and a clear gradient of the same variable was evident from the lowest to the highest PbB level. Focusing on subjects with one child only, the Cox model confirmed no significant difference in fecundability between exposed and not exposed, whereas a statistically significant longer TTP was associated to the exposure level >/= 40 microg/dl.

CONCLUSIONS

It is not easy to assert or to deny the effect of inorganic lead on male fecundity, quantitatively estimated by TTP, with the data available for this study. In fact, while the general data seem to exclude effects of Pb on male fecundability a more detailed analysis suggests an unfavorable effect at relatively high levels of exposure but some confounding attributable to personal and social conditions of the workers cannot be ruled out. Further investigations with a better control of confounding are needed.

Appropriate use of animal models in the assessment of risk during prenatal development: an illustration using inorganic arsenic

BACKGROUND

Assessing risks to human development from chemical exposure typically requires integrating findings from laboratory animal and human studies.

METHODS

Using a case study approach, we present a program designed to assess the risk of the occurrence of malformations from inorganic arsenic exposure. We discuss how epidemiological data should be evaluated for quality and criteria for determining whether an association is causal. In this case study, adequate epidemiological data were not available for evaluating the potential effect of arsenic on development. Consequently, results from appropriately designed, conducted, and interpreted developmental toxicity studies, which have been shown to be predictive of human risk under numerous scenarios, were used. In our case study, the existing animal data were not designed appropriately to assess risk from environmental exposures, although such studies may be useful for hazard identification. Because the human and animal databases were deficient, a research program comprising modern guideline toxicological studies was designed and conducted.

RESULTS

The results of those studies in rats, mice, and rabbits indicate that oral and inhalational exposures to inorganic arsenic do not cause structural malformations, and inhalational exposures produced no developmental effects at all. The new study results are discussed in conjunction with considerations of metabolism, toxicokinetics, and maternal toxicity.

CONCLUSIONS

Based on the available experimental data, and absent contrary findings from adequately conducted epidemiological studies, we conclude that exposure to inorganic arsenic by environmentally relevant routes poses no risk of the occurrence of malformations and little risk of other prenatal developmental toxicity in developing humans without concomitant and near-lethal toxicological effects in mothers.

An assessment of the developmental toxicity of inorganic arsenic

A critical analysis of the literature base regarding the reproductive and developmental toxicity of arsenic compounds, with emphasis on inorganic arsenicals, was conducted. The analysis was stimulated by the great number of papers that have purported to have shown an association between exposure of pregnant laboratory animals to arsenic compounds and the occurrence of offspring with cranial neural tube defects, particularly exencephaly. For the most part, the literature reports of arsenic developmental toxicity in experimental animals are inadequate for human risk assessment purposes. Despite the shortcomings of the experimental database, several conclusions are readily apparent when the animal studies are viewed collectively. First, cranial neural tube defects are induced in rodents only when arsenic exposure has occurred early in gestation (on Days 7 [hamster, mouse], 8 [mouse], or 9 [rat]). Second, arsenic exposures that cause cranial neural tube defects are single doses that are so high as to be lethal (or nearly so) to the pregnant animal. Third, the effective routes of exposure are by injection directly into the venous system or the peritoneal cavity; even massive oral exposures do not cause increases in the incidence of total gross malformations. Fourth, repetition of similar study designs employing exaggerated parenteral doses is the source of the large number of papers reporting neural tube defects associated with prenatal arsenic exposure. Fifth, in five repeated dose studies carried out following EPA Guidelines for assessing developmental toxicity, arsenic was not teratogenic in rats (AsIII, 101 micromol/kg/d, oral gavage; 101 micromol/m3, inhalation), mice (AsV, 338 micromol/kg/d, oral gavage; est. 402 micromol/kg/d, diet), or rabbits (AsV, 21 micromol/kg/d, oral gavage). Data regarding arsenic exposure and adverse outcomes of pregnancy in humans are limited to several ecologic epidemiology studies of drinking water, airborne dusts, and smelter environs. These studies failed to (1) obtain accurate measurements of maternal exposure during the critical period of organogenesis and (2) control for recognized confounders. The lone study that examined maternal arsenic exposure during pregnancy and the presence of neural tube defects in progeny failed to confirm a relationship between the two. It is concluded that under environmentally relevant exposure scenarios (e.g., 100 ppm in soil), inorganic arsenic is unlikely to pose a risk to pregnant women and their offspring.

Developmental and reproductive toxicity of inorganic arsenic: animal studies and human concerns

Information on the reproductive and developmental toxicity of inorganic arsenic is available primarily from studies in animals using arsenite and arsenate salts and arsenic trioxide. Inorganic arsenic has been extensively studied as a teratogen in animals. Data from animal studies demonstrate that arsenic can produce developmental toxicity, including malformation, death, and growth retardation, in four species (hamsters, mice, rats, rabbits). A characteristic pattern of malformations is produced, and the developmental toxicity effects are dependent on dose, route, and the day of gestation when exposure occurs. Studies with gavage and diet administration indicate that death and growth retardation are produced by oral arsenic exposure. Arsenic is readily transferred to the fetus and produces developmental toxicity in embryo culture. Animal studies have not identified an effect of arsenic on fertility in males or females. When females were dosed chronically for periods that included pregnancy, the primary effect of arsenic on reproduction was a dose-dependent increase in conceptus mortality and in postnatal growth retardation. Human data are limited to a few studies of populations exposed to arsenic from drinking water or from working at or living near smelters. Associations with spontaneous abortion and stillbirth have been reported in more than one of these studies, but interpretation of these studies is complicated because study populations were exposed to multiple chemicals. Thus, animal studies suggest that environmental arsenic exposures are primarily a risk to the developing fetus. In order to understand the implications for humans, attention must be given to comparative pharmacokinetics and metabolism, likely exposure scenarios, possible mechanisms of action, and the potential role of arsenic as an essential nutrient.

Chronic lead exposure effects in the cynomolgus monkey (Macaca fascicularis) testis

Although reproductive consequences of high circulating blood lead levels (> or = 60 micrograms/dL) have been reported, potential adverse effects of chronic lead exposure in males that result in low to moderate blood lead levels (10-25 and 26-60 micrograms/dL, respectively) are unknown. Effects of chronic lead exposure to testis ultrastructure were determined in the cynomolgus monkey after oral administration of lead acetate (1500 micrograms/kg BW/day) in a vehicle in the following groups: from birth to 10 years (lifetime), postnatal day 300 to 10 years (postinfancy), and postnatal day 0-400 (infancy); monkeys in the control group received only the vehicle (95% glycerol and 5% distilled water). At age 10 years, circulating lead concentrations in lifetime and postinfancy-dosed monkeys were approximately 35 micrograms/dL, and in control and infancy animals the concentrations were < 1.0 microgram/dL. Sertoli and spermatogenic cells of dosed monkeys from the infancy and lifetime groups revealed injuries. Chronic exposure to lead that results in moderate blood lead concentrations induced persistent ultrastructural alterations in the cynomolgus monkey testis. Results of this study on the primate, following extrapolation to humans, could influence further refining of the impact of environmental lead contamination concentrations vis-à-vis the health of children, adults, and aged human beings.

Role of arsenic as a reproductive toxin with particular attention to neural tube defects

Arsenic has been recognized as a human toxicant for over 2000 years. More recently it has been readily accepted as a human carcinogen. Animal research has demonstrated arsenic's ability to have profound detrimental effects on the developing embryo in avian and mammalian species. This article comprehensively reviews the human and animal literature on the subject of the reproductive toxicity of arsenic. A variety of endpoints are considered, including spontaneous abortion, cardiovascular defects, and arsenic's role in the causation of neural tube defects (NTDs). A summary of the literature that has examined the various postulated mechanisms by which arsenic may produce NTDs is also considered. In addition, a discussion of literature relative to the presence of arsenic in the general environment and in the workplace is presented. This article reaches the conclusion that while further research is clearly needed, particularly on the potential toxicity of organic arsenical compounds, the current literature suggests it may be prudent and appropriate to treat inorganic arsenic as a probable human reproductive toxin.

History of maternal fetal loss and increased risk of childhood acute leukemia at an early age. A report from the Childrens Cancer Group

BACKGROUND

Maternal reproductive history of fetal loss previously has been reported to be associated with an increased risk of leukemia in subsequent offspring. Data from a Childrens Cancer Group (CCG) case-control study were analyzed to test the hypothesis that this association was dependent on the number of previous fetal losses and age at leukemia diagnosis.

METHODS

A case-control study using a large Childrens Cancer Group database examined maternal history of fetal loss as a risk factor for childhood leukemia in subsequent offspring. One thousand seven hundred fifty-three patients with childhood acute leukemia were compared with 839 community control subjects s and 2081 nonleukemia cancer control subjects.

RESULTS

A modest increase in risk was found to be associated with a history of fetal loss. Stratification by age at diagnosis of leukemia showed that this association was significant only for those patients diagnosed before 4 years of age and most significant in those patients diagnosed before 2 years of age. When comparing community controls with patients acute lymphocytic leukemia diagnosed before 2 years of age, one previous fetal loss was associated with a five-fold increased risk (P < 0.001) whereas two or more fetal losses were associated with a relative risk of 24.8 (P < 0.001). Similarly, patients with acute myelocytic leukemia diagnosed before 2 years of age demonstrated 5-fold and 12-fold increased risks associated with the previous fetal loss and 2 or more previous fetal losses, respectively.

CONCLUSIONS

Childhood acute leukemia occurring at younger ages may be associated with an underlying genetic abnormality or chronic environmental exposure, which can be either lethal to the developing fetus or mutagenic and result in the development of acute leukemia.

Human trophoblast cultures: models for implantation and peri-implantation toxicology

Implantation is the process that leads from blastocyst attachment to its embedding in the uterine wall. It is widely believed that failure of implantation is a common cause of pregnancy loss. Toxic agents can interfere directly with the process of implantation and therefore may account for unexplained implantation failures. Our knowledge of human implantation remains limited, mainly due to the lack of adequate experimental models. Studies of mechanisms underlying implantation in humans are by nature and for ethical reasons restricted to in vitro models. The aim of this review is to provide a critical evaluation of various in vitro models of implantation in humans, as well as essential background knowledge required for application of these models to the assessment of peri-implantation toxicity. Particular attention has been devoted to cell-cell and cell-matrix interactions as possible endpoints in the screening of toxic agents.

Reproductive toxicity of chronic lead exposure in the female cynomolgus monkey

The effect of chronic lead (Pb) exposure on menstrual function and circulating concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), estradiol (E2) and progesterone (P4) were studied in female nulliparous cynomolgus monkeys (n = 32). Pb acetate (1500 micrograms/kg BW/day) was administered by capsule to monkeys in teh following groups; exposure from birth to 10 years (lifetime, n = 8), postnatal day 300 to 10 years (adolescent, n = 8), and postnatal days 0 to 400 (childhood, n = 8). Monkeys in the control group (n = 8) received gelatin capsules containing the vehicle only. Reproductive assessment of these monkeys was performed between 9 and 10 years, during which time the blood Pb levels in the lifetime and adolescent exposure groups were approximately 35 micrograms/dL. No overt signs of Pb-induced toxicity were found in the general health or menstrual function. However, Pb treatment significantly suppressed circulating levels of LH (P less than 0.042), FSH (P less than 0.041), and E2 (P less than 0.0001) during the menstrual cycle. Pb treatment had no effect on plasma concentrations of P4. These data indicate that chronic Pb exposure results in subclinical suppression of circulating concentrations LH, FSH, and E2 without producing overt signs of menstrual irregularity.

Inorganic arsenic compounds: are they carcinogenic, mutagenic, teratogenic?

This review examines and evaluates the literature on the ability of inorganic arsenic compounds to cause cancer in humans and laboratory animals. The epidemiological data that supports the position that inorganic arsenical derivatives are carcinogenic in humans is convincing and difficult to deny because of their consistency. These data are from studies of different occupational exposures such as smelter and pesticide workers, as well as from studies of drinking water, wines and medicinal tonics that contained or were contaminated with inorganic compounds of arsenic. Indeed, positive dose-response relationships between cancer incidence or mortality with many inorganic arsenical substances have been shown. Despite the presence of data which confuse the interpretation and evaluation of epidemiological data, associated neoplasms of the lungs, skin and gastrointestinal systems have been observed as a result of exposure to inorganic arsenic compounds.The mechanism of carcinogenicity of inorganic arsenical substances in humans is unknown. Inorganic arsenic compounds are not carcinogenic in laboratory animals by most routes of administration. However, further studies (subchronic, chronic, carcinogenic) using intratracheal and other conventional routes in other animal species would appear to be warranted. Moreso, especially since there is no evidence that organic arsenic compounds are carcinogenic in numerous mammalian species. Inorganic derivatives of arsenic are not mutagenic but may be teraiogenic. This latter conclusion is dependent on the method of administration and size of the dose, as well as on the species of animal used for the study.

Reversibility of the effects of lead on the reproductive performance of female rats

Potential reversibility of the reproductive effect of lead was studied in female albino rats after cessation of oral exposure to 7500 ppm lead as acetate in drinking water. Females mated and gave birth to their first offspring during 9 weeks of lead exposure. They then continued or discontinued exposure, were mated for the second time, and had their second offspring during a longer exposure (20 weeks) or after a period without lead. Food consumption, body weights, and fertility index were not altered irrespective of the exposure conditions. In the first and especially in the second offspring of exposed females, survival rates, litter sizes, and body weights of newborn and 11-day-old pups were decreased. Offspring born to dams in which exposure had been stopped were not different from controls. It was concluded that the adverse reproductive action of lead is reversible after withdrawal of the female from exposure.

The influence of lead ions on uterine activity in the rat

Spontaneous uterine activity and reactivity to oxytocin, naproxen and PGF2 alpha were studied in vitro in 80 rats, which for 2-8 weeks had been exposed to different concentrations and combinations of Pb2+, Zn2+ and Cu2+ in their water supply or had been given clean water for control. In rats given only Pb2+ in concentrations of 1000 and 500 ppm for 6 weeks the uterine activity was significantly increased, whereas in groups given the other ions alone, or Pb2+ for 6 weeks followed by 2 weeks of clean water or Zn2+ or Cu2+ no change was observed. The responses to the oxytocin, naproxen and PGF2 alpha did not differ. These results suggest that contamination with lead ions might be one of the etiological factors involved in conditions with increased uterine activity.

Past pregnancy outcomes among women living in the vicinity of a lead smelter in Kosovo, Yugoslavia

This analysis compares the rates of spontaneous abortion among women living in the vicinity of a lead smelter with those of women living in a town where blood lead levels were low. Data derive from the obstetric histories of both groups of women obtained while seeking prenatal care for a later pregnancy. A total of 639 women (304 exposed, 335 unexposed) had at least one previous pregnancy and lived at the same address since their first pregnancy. The geometric mean blood lead concentrations in the sample at the time of the interviews were 0.77 mumol/L in the exposed town and 0.25 mumol/L in the unexposed town. The rates of spontaneous abortions in first pregnancies were similar, with 16.4 percent of women in the exposed town and 14.0 percent in the unexposed town reporting loss. The adjusted odds ratio relating town of residence to spontaneous abortion was 1.1 (95% CI = 0.9, 1.4). This analysis represents the first systematic attempt to seek an association between environmental lead exposure and spontaneous abortion. As such, the failure to find a positive association strongly suggests that at the levels of exposure represented in our sample, such an association does not exist.

Impact of medical genetics on environmental medicine

Medical genetics as a discipline has contributed basic knowledge of great applicability in environmental medicine, e.g. 1) the demonstration that environmental agents may cause chromosomal damage, 2) that chromosome aberrations are correlated with increased risks for cancer and spontaneous abortion, and 3) that the susceptibility to cyto- and genotoxic damage may be influenced by genetic factors. This paper discusses examples of applications of genetic knowledge in environmental medicine and areas for future research.

Quality of community drinking water and the occurrence of spontaneous abortion

To investigate the relationship between community drinking water quality and spontaneous abortion, we compared trace element levels in the drinking water of 286 women having a spontaneous abortion through 27 wk gestation with that of 1,391 women having livebirths. Trace element levels were gathered from routine analyses of public tap water supplies from the communities where the women resided during pregnancy. After adjustment for potential confounders, an increase in the frequency of spontaneous abortion was associated with detectable levels of mercury; high levels of arsenic, potassium, and silica; moderately hard water, and surface water. In contrast, a decrease in the frequency of spontaneous abortion was associated with high levels of alkalinity and sulfate, and any detectable level of nitrate. These results require further corroboration because there is a paucity of data investigating this issue.

Ovarian toxicity of benzo(a)pyrene and metabolites in mice

The effect of intraovarian injection of benzo(a)pyrene (BP) or one of three metabolites: +7,8-oxide (7,8-O), (-)-dihydrodiol (DHD), and (+)-diol-epoxide-2 (DE2) on ovarian volume, weight, and follicle number was investigated in DBA/2N (D2), C57BL/6N (B6), and (DBA/2N x C57BL/6N)F1 (F1) mice. Female mice, 6 to 8 weeks old, were treated by injection into the right ovary with the indicated compound (10 micrograms in 1 microL DMSO). The left ovary was untreated. Two weeks following treatment both ovaries were removed, fixed in Bouin's medium, serially sectioned, and stained with hematoxylin and eosin. Right ovarian weight was decreased in D2 mice treated with BP (P less than 0.01 and DHD (P less than 0.01). Left ovarian weight was increased in D2 mice treated with DE2 (P less than 0.05). BP decreased right ovarian volume in D2 (P less than 0.01) and F1 (P less than 0.01) mice. 7,8-O decreased right ovarian volume in D2 mice (P less than 0.05). DHD decreased right ovarian volume in D2 (P less than 0.01) and F1 (P less than 0.05) mice. DE2 decreased right ovarian volume in D2 (P less than 0.01) and F1 (P less than 0.01) mice. Left ovarian volume was increased in B6 (P less than 0.01) and D2 (P less than 0.05) mice treated with DE2. The number of small follicles was decreased in D2, B6, and F1 mice treated with DE2 (P less than 0.01). BP and DHD also decreased small follicle number in D2 and F1 mice (P less than 0.01). The number of growing follicles was decreased in B6, D2, and F1 mice treated with DE2 (P less than 0.01). Treatment with DHD decreased the number of growing follicles in D2 mice (P less than 0.05). The number of antral follicles was reduced in F1 mice treated with BP (P less than 0.05), DHD (P less than 0.01), and DE2 (P less than 0.01). The number of antral follicles was also reduced in B6 mice treated with DE2 (P less than 0.01) and in D2 mice treated with DHD (P less than 0.05) and D2 mice treated with DE2 (P less than 0.01). These experiments suggest that toxic effects to one ovary may result in compensatory hypertrophy of the contralateral ovary. Morphometric analysis of the ovary, including ovarian volume, represents a useful objective measure of ovarian toxicity.

Potential human developmental toxicants and the role of animal testing in their identification and characterization

Some 50 chemicals have been identified from environmental, occupational, or therapeutic exposure data as being potential developmental toxicants in humans. The toxicity pattern of these chemicals in humans has been characterized and correlated with developmental toxicity end points in laboratory animal models in order to determine the relevance and predictiveness of the results of testing in animals in extrapolation to human data. In general, animal developmental toxicity data closely paralleled human outcomes, and while humans in most cases were more sensitive than animals, the data support the concept that, imperfections aside, studies in animals serve a vital role in the hazard identification process.

Intrauterine exposure to low levels of lead: the status of the neonate

It has been suggested that lead (Pb) at low exposure levels is a behavioral teratogen. Blood lead (Pb-B) was measured in 185 samples of maternal blood and in 162 samples of cord blood drawn from members of a cohort of mother-infant pairs. Routine newborn assessments, an examination for minor anomalies, the Brazelton Neonatal Behavioral Assessment (NBAS), and part of the Graham/Rosenblith Behavioral Examination (G/R) were administered. Maternal and cord Pb-B correlated 0.80. In regression analyses, Apgar scores, birthweight, length, head circumference, neonatal anomalies, and seven behavioral scales were unrelated to either maternal or cord Pb-B. Three scales--the NBAS Abnormal Reflexes, the G/R Neurological Soft Sign, and the G/R Muscle Tonus Scales--were related minimally to either cord or maternal Pb-B. Because of the contrast in maternal and cord results, despite the high correlation of maternal and cord Pb-B, the data were reanalyzed for 132 cases with paired data. Only the Soft Sign Scale remained significant and that only for cord, but not maternal Pb-B. Regression analysis revealed a suppression with the Soft Sign Scale related to the variance of the cord Pb-B that was not common with maternal Pb-B. The possibility that the fetus under stress tends to accumulate Pb was considered.

Clinical and environmental aspects of arsenic toxicity

Arsenic is widely distributed throughout the animal and plant kingdoms and our environment where sources can be natural or anthropogenic. Agricultural uses of arsenic have declined recently, but it still has well-defined roles in industry. Small amounts of arsenic are metabolized in a variety of ways and are largely rapidly methylated and excreted by man and animals. Poisoning can occur and may follow an acute or chronic course. Toxic manifestations in man occur at the cellular level and may appear in many organ systems. Specific effects can often be demonstrated in the skin and in the vascular and nervous systems. Other toxic effects appear to include carcinogenesis, mutagenesis, and teratogenesis.

Evaluation of the effect of BAL (2,3-dimercaptopropanol) on arsenite-induced teratogenesis in mice

The effect of the chelating agent dimercaprol (BAL) on the embryotoxic and teratogenic effects of arsenite (As3+) was determined. BAL (sc, 30 mg/kg) was administered to pregnant CD-1 mice, either 8 and 4 hr prior to or 4 and 8 hr after a 12-mg/kg ip dose of arsenite; other females received a single sc injection of 60 mg/kg BAL concurrently with the arsenite. Treatments were given on Gestation Day 9 or 12 (copulation plug = Day 1). Controls received sc corn oil or ip H2O, with or without arsenite or BAL. Arsenite treatment caused gross and skeletal malformations and prenatal deaths, while controls were unaffected. When BAL was given prior to arsenite on Day 9, incidences of prenatal mortality and skeletal malformation were significantly diminished, and on Day 12, BAL protected against fetocidal effects of arsenite when given concurrently with the arsenite. No other significant protective effects against arsenite toxicity were seen due to BAL; however, concurrent BAL treatment on Day 9 appeared to result in decreased fetal mortality and a decline in skeletal malformations. BAL given following arsenite on Day 9 afforded no significant protection against the arsenic, although an apparent decrease in gross and skeletal malformations was suggestive of such an effect. According to these results, BAL is unlikely to have a practical beneficial effect on the arsenite exposed conceptus, because it must be administered prior to the teratogen (or perhaps simultaneously with it) to be effective.

Spontaneous abortions among laboratory workers; a follow up study

An investigation was conducted among all female laboratory workers in the county of Funen to test the hypothesis that work in laboratories during pregnancy increases the risk of spontaneous abortion. Laboratory workers from hospital, university, and other public laboratories and from laboratories in industry were investigated. A socially comparable reference group less exposed to chemicals at work included office workers, technical assistants and designers, physiotherapists, and occupational therapists. Information was obtained through a postal questionnaire study in May 1980 and from hospital records. Neither the occupation in any single category of laboratory nor the alleged exposure to any single chemical during pregnancy showed a significant increase in the odds ratio for spontaneous abortion. A selection bias was found among the non-respondents with respect to both occupation and outcome of pregnancy, but the influence on the results was slight, owing to the small number of non-respondents. The higher rates of hospital admission for spontaneous abortion among the cases compared with the controls indicates that register data are not more valid than self reported data. This leads to several methodological problems that ought to be studied in further detail.

Mortality patterns in a population living near a copper smelter

An attempt to investigate the effects of pollution by a copper smelter on an adjacent community was carried out by studying the mortality patterns in Rouyn-Noranda, Province of Quebec, compared to the mortality in Val d'Or (a control community of the same area) and the whole province, during the period 1965-1974. The study shows, in Rouyn-Noranda, an excess of deaths by lung cancer, chronic respiratory diseases, and diseases of the digestive system among men and this excess remains even after adjustment for occupational exposure and could not be attributed to smoking habits either. Among women, deaths by endocrine and metabolic diseases and chronic respiratory diseases are in excess in Rouyn-Noranda.

Spontaneous abortions in an industrialized community in Finland

Spontaneous abortions were analyzed in an industrialized Finnish community according to the occupation and workplace of both the women and their husbands. Information about spontaneous abortions and births was obtained from the hospital discharge register, and data about the women and their families were collected from census files. When compared with all women employed outside the home, women who worked at a textile plant (factory A, a clothing manufacturer) had an increased rate of spontaneous abortion (16.7 per cent vs 11.4 per cent). The rate of spontaneous abortions among women employed at factory A differed according to the husband's workplace. The odds ratio for women employed at factor A whose husbands worked at a large metallurgical factory was 3.8, whereas the odds ratio for women whose husbands worked elsewhere was 1.2. Between 1973 and 1976, the rate of spontaneous abortions in this town was consistently lower for the summer period. (May-August) than for the other periods of the year.

Community study of spontaneous abortions: relation to occupation and air pollution by sulfur dioxide, hydrogen sulfide, and carbon disulfide

Spontaneous abortions were analyzed in an industrial community in Finland in relation to the occupation of women and their husbands, and to the level of air pollution in the family's residential area. Information on abortions and births was obtained from the hospital discharge register; information on the women and their families was obtained from the files of the population and housing census. Women who were employed in rayon textile jobs and paper products jobs had an increased rate (P less than 0.10) of spontaneous abortions; the wives of men employed in transport and communication, in rayon textile jobs, and in chemical process jobs also had an increased rate of spontaneous abortions. In material stratified for age, parity, and socioeconomic class no evidence was found that the level of sulfur dioxide or carbon disulfide could be associated with a risk of spontaneous abortions. More spontaneous abortions were noted in all socioeconomic classes in areas where the mean annual level of hydrogen sulfide exceeded 4 micrograms m-3. However, the difference (total rates 7.6 and 9.3, respectively) was not significant statistically.

Autoradiographic studies on the distribution of arsenic in mice and hamsters administered 74As-arsenite or -arsenate

Whole-body autoradiography in combination with other determinations of tissue levels of 74As-arsenic in mice, 5 min. to 30 days after intravenous injections of 74As-arsenite (As III) or -arsenate (As V), showed higher organ concentrations and whole-body retention of arsenic in the As III mice as compared to the As V mice. Only the kidneys (at short time intervals) and the skeleton had higher levels in the As V mice as compared to the As III mice. The skeletal accumulation of As V is probably due to the resemblance of the arsenate to phosphate, so that arsenate may substitute for phosphate in the apatite crystal. The long-term retention of arsenic was most apparent in hair and skin, squamous epithelium of the upper gastrointestinal tract (oral cavity, oesophagus, and the oesophageal part of the stomach mucosa), the epididymis, thyroid, lens and skeleton. The accumulation in hair, skin and the upper gastrointestinal tract may be ascribed to a binding to keratin, the content of which is high in squamous epithelia. The distribution of arsenic in golden hamsters was similar to that found in mice. The significance of the findings in relation to reported adverse effects of inorganic arsenic is discussed.

Increased frequencies of chromosomal abnormalities in families with a history of fetal wastage

In twenty couples with a history of repeated fetal wastage, chromosomal abnormalities in cultured lymphocytes were analyzed with standard, G- and C-banding techniques. The analyses revealed five individuals with a variant chromosome #1 (1 qh+) and one individual with an extra small unidentifiable fragment or ring chromosome in about 50% of the cells. In the remaining 14 couples, an increased frequency of chromosomal breakage was found, compared to the frequencies in 11 couples with two children and no reported abortions. Eighteen out of 40 individuals (45%) in the families with fetal wastage were found to have cytogenetic abnormalities. None of the 22 controls showed such abnormalities.

Spontaneous abortions among women employed in the metal industry in Finland

Spontaneous abortions were analyzed among Finnish metal workers between 1973 and 1976. The information on the workers (35,000 women) was obtained from the files of the Union of Metal Workers; information on the abortions was obtained from the Hospital discharge registry of the National Board of Health. Among metal workers 195 spontaneous abortions were recorded. The proportion of spontaneous abortions was 7.82% (spontaneous abortions/pregnancies, rate) and 13.79% (spontaneous abortions/births, ratio) of which the latter figure was significantly higher (P < 0.05) than the respective one among all Finnish women. Both the rate and the ratio were significantly increased upon joining the Union as analyzed from an age-standardized material. A particular risk industry appeared to be the production of radios, televisions, and their components. An exposure to solder fumes was suggested to explain the increased risk.

Transplacental carcinogens and mutagens: childhood cancer, malformations, and abortions as risk indicators

Childhood cancer, malformations, and spontaneous abortions in Finland were analyzed according to the parents' occupations. Children of women working in the food industry and farming and of men working in motor vehicle driving and farming appeared to have an elevated risk of cancer. Women in industrial and construction occupations had an increased risk of having malformed children and spontaneous abortions.