Prenatal and early childhood exposure to tetrachloroethylene and adult vision

Maternal long-term inhalation exposure to perchloroethylene and prenatal teratogenicity: morphometric, hormonal, and histological study

Some commonly used chemicals have teratogenic effects. Perchloroethylene (PCE) is a liquid that is widely used in various industries and drying clothes. In this study, the teratogenic effects of PCE in rat embryos were investigated. In this experimental study, 32 adult Wistar female rats in the weight range of 230-250 g were used. Female rats were randomly divided into 4 groups (n = 8). Control group (without PCE inhalation), experimental group G(I) (exposed to PCE 18 days prior to mating), experimental group G(II) (exposed to PCE 18 days after mating) and experimental group G(III) (exposed to PCE 18 days before and 18 days after mating). Pregnant rats were anesthetized on the 18th day of gestation and then serum and embryos were removed for the required studies. Embryos were examined for number, weight, sex, morphometric parameters of organs, and tissue samples were prepared for histological studies. Serum isolated from dams were evaluated for sexual and gonadal hormones. The results of this study showed that PCE has teratogenic effects on rat embryos. Infertility and reduced birth rate were other effects of PCE in rats. PCE has teratogenic effects and impairs the reproductive system of rats.

Understanding exposures and latent disease risk within the National Institute of Environmental Health Sciences Superfund Research Program

Understanding the health effects of exposures when there is a lag between exposure and the onset of disease is an important and challenging topic in environmental health research. The National Institute of Environmental Health Sciences (NIEHS) Superfund Basic Research and Training Program (SRP) is a National Institutes of Health (NIH) grant program that uses a multidisciplinary approach to support biomedical and environmental science and engineering research. Because of the multidisciplinary nature of the program, SRP grantees are well-positioned to study exposure and latent disease risk across humans, animal models, and various life stages. SRP-funded scientists are working to address the challenge of connecting exposures that occur early in life and prior to conception with diseases that manifest much later, including developing new tools and approaches to predict how chemicals may affect long-term health. Here, we highlight research from the SRP focused on understanding the health effects of exposures with a lag between exposure and the onset of the disease as well as provide future directions for addressing knowledge gaps for this highly complex and challenging topic. Advancing the knowledge of latency to disease will require a multidisciplinary approach to research, the need for data sharing and integration, and new tools and computation approaches to make better predications about the timing of disease onset. A better understanding of exposures that may contribute to later-life diseases is essential to supporting the implementation of prevention and intervention strategies to reduce or modulate exposures to reduce disease burden.

Prenatal and early childhood exposure to tetrachloroethylene (PCE)-contaminated drinking water and sleep quality in adulthood: a retrospective cohort study

BACKGROUND

Communities in Cape Cod, Massachusetts were exposed to tetrachloroethylene (PCE) through contaminated drinking water from 1969 to 1983. PCE exposure during adulthood has well-established neurotoxic effects; however, long-term impacts stemming from early life exposure, especially adverse effects on sleep quality, are not well understood.

METHODS

The present analysis was based on data from the Cape Cod Health Study, a retrospective cohort study of the long-term neurotoxic impacts of early-life exposure to PCE-contaminated drinking water. Exposure to PCE-contaminated water was estimated using a validated leaching and transport model. Measures of sleep quality were obtained from self-administered questionnaires. Generalized estimating equations were used to generate risk ratios and 95% confidence intervals to estimate the association between early-life PCE exposure and sleep quality among 604 participants.

RESULTS

Compared to unexposed participants, any PCE exposure during early life was associated with 1.57 times the risk of reporting breathing pauses during sleep (95% CI 0.92-2.68). Low-level exposure to PCE was associated with 1.50 times the risk of reporting sleep apnea or other sleep disorders (95% CI 0.78-2.89), while high levels of exposure had comparable risk compared to no exposure (RR = 0.94, 95% CI 0.50-1.79). Weak or no associations were observed for other sleep quality outcomes. In stratified analyses participants with mental illness and/or substance use disorder had increased risk ratios for short sleep duration associated with PCE exposure.

CONCLUSION

These findings suggest that early-life exposure to PCE may be associated with a moderate increase in the risk of reporting breathing pauses during sleep in adulthood and that a history of mental illness and/or substance use disorder may exacerbate the risk of short sleep duration.

Prenatal and early childhood exposure to tetrachloroethylene (PCE) and non-medical use of prescription drugs: A retrospective cohort study in Cape Cod, MA

BACKGROUND

Between 1968 and 1983, public drinking water supplies of Cape Cod, Massachusetts were contaminated with the chlorinated solvent tetrachloroethylene (PCE). We previously found an affinity for risk-taking behaviors, including the use of illicit drugs, following prenatal and early childhood exposure to PCE. Using newly collected data, we investigated the risk of non-medical use of prescription drugs (NMUPD) following prenatal and early childhood PCE exposure.

METHODS

Participants were identified from a retrospective cohort study ("Cape Cod Health Study") via cross-matching birth certificates and water system data. The original self-administered questionnaire gathered data on demographics, work and medical history, and alcohol and illicit drug use from 618 individuals (363 exposed and 255 unexposed). The follow-up survey added questions on non-medical use of prescription pain relievers, tranquilizers, stimulants and sedatives. A validated leaching and transport model was used to estimate exposure to PCE exposure in drinking water.

RESULTS

There was a wide distribution of cumulative prenatal and early childhood PCE exposure levels (range: 0.04 g-3722.2 g). PCE exposed subjects had a 1.92-fold increase in risk of any non-medical use of prescription drugs [Adjusted RR: 1.92, (95% CI: 1.31, 2.83)]. Furthermore, the association followed a dose-response relationship where the risk of NMUPD was higher for those exposed to PCE levels greater than or equal the median level versus those exposed to levels less than the median [Adjusted RR: 2.05 (95% CI: 1.34, 3.15) vs. 1.83 (95% CI: 1.20, 2.79) (p-value for trend < 0.01)]. Additionally, we found moderate increases in risk by level of non-medical use (any non-medical use, non-medical use of 1 or more categories of prescription drugs, or 2+ categories) as well as by category of drug for pain relivers, stimulants and tranquilizers.

CONCLUSION

We found that prenatal and early childhood exposure to PCE was associated with a moderate increase in the risk of NMUPD. Exposed subjects had dose-related increased risks of NMUPD of pain relievers, tranquilizers, and stimulants. This study has a number of limitations and is the first to report this association. Additional longitudinal studies of populations exposed to PCE during early life should be conducted to examine its long-term neurotoxic effects.

Perchloroethylene and Dry Cleaning: It's Time to Move the Industry to Safer Alternatives

Perchloroethylene (PERC) is the most common solvent used for dry cleaning in the United States. PERC is a reproductive toxicant, neurotoxicant, potential human carcinogen, and a persistent environmental pollutant. The Environmental Protection Agency is evaluating PERC under the Frank R. Lautenberg Chemical Safety for the 21st Century Act, which amended the Toxic Substances Control Act (amended TSCA), and has mandated that PERC dry cleaning machines be removed from residential buildings. Some local and state programs are also requiring or facilitating transitions to alternative cleaning technologies. However, the potential for these alternatives to harm human health and the environment is not well-understood. This review describes the issues surrounding the use of PERC and alternative solvents for dry cleaning while highlighting the lessons learned from a local government program that transitioned PERC dry cleaners to the safest current alternative: professional wet cleaning. Implications for future public health research and policy are discussed: (1) we must move away from PERC, (2) any transition must account for the economic instability and cultural aspects of the people who work in the industry, (3) legacy contamination must be addressed even after safer alternatives are adopted, and (4) evaluations of PERC alternatives are needed to determine their implications for the long-term health and sustainability of the people who work in the industry.

Prenatal exposure to glycol ethers and visual contrast sensitivity in 6-year-old children in the PELAGIE mother-child cohort

BACKGROUND

Maternal occupational exposure to organic solvents during pregnancy has been associated with decreased visual function in offspring. Glycol ethers (GEs) belong to oxygenated solvents and are widely used both in occupational and domestic contexts.

OBJECTIVES

We aimed to assess associations between prenatal GEs exposure and contrast sensitivity in children.

METHODS

Six GE alkoxy carboxylic acidic metabolites (methoxyacetic acid [MAA], ethoxyacetic acid [EAA], ethoxyethoxyacetic acid [EEAA], butoxyacetic acid [BAA], phenoxyacetic acid [PhAA], and 2-methoxypropionic acid [2-MPA]) were measured in first morning void urine samples collected from 220 early-pregnancy women, in the mother-child PELAGIE cohort (France). Trained investigators administered the Functional Acuity Contrast Test (FACT) to the 6-year-old children, providing scores for 5 spatial frequencies (1.5-18 cycles per degree (cpd)). We standardized biomarker urinary concentrations on urine sampling conditions. Values below the LOD were imputed based on log-normal distribution, generating five datasets for multiple imputation. Linear regression models were adjusted for potential confounders.

RESULTS

GE metabolites were detected in 70-98% of maternal urine samples. Phenoxyacetic acid (PhAA) had the highest median concentration (0.33 mg/L), and 2-methoxypropionic acid (2-MPA) the lowest (0.01 mg/L). Children with higher prenatal PhAA concentrations had poorer FACT scores at various spatial frequencies (fourth vs. first quartile: β_18cpd = -0.90 (95% confidence interval CI = -1.64, -0.16), β_12cpd = -0.92 (95%CI = -1.55, -0.29) and β_1.5cpd = -0.69 (95%CI = -1.19, -0.20)). The 2-MPA log-scale concentration was negatively associated with the FACT score at the 3-cpd stimulus.

DISCUSSION

PhAA is the metabolite of ethylene glycol monophenyl ether present in many cosmetics. 2-MPA is the metabolite of an isomer of propylene glycol methyl ether commonly present in household and industrial cleaning products. Although evidence of biological plausibility is lacking, the study suggests adverse impact of ubiquitous prenatal exposure to some GE on visual functioning among children.

Long-term Neurotoxic Effects of Early-life Exposure to Tetrachloroethylene-contaminated Drinking Water

BACKGROUND

Tetrachloroethene (PCE) is a common environmental and occupational contaminant and an acknowledged neurotoxicant. From 1968 through 1983, widespread contamination of public drinking water supplies with PCE occurred in the Cape Cod region of Massachusetts. The source of the contamination was a vinyl liner applied to the inner surface of water distribution pipes.

OBJECTIVES

A retrospective cohort study (the Cape Cod Health Study) was undertaken to examine possible health consequences of early-life exposure to PCE-contaminated drinking water. This review describes the study methods and findings regarding the effects of prenatal and childhood exposure on neurologic outcomes during early adulthood, including vision, neuropsychological functioning, brain structure, risky behaviors, and mental illness. The review also describes the strengths and challenges of conducting population-based epidemiologic research in this unique setting.

METHODS

Participants were identified by cross-matching birth certificates and water system data. Information on health outcomes and confounding variables was collected from self-administered surveys (n = 1689), neuropsychological tests (n = 63), vision examinations (n = 63), and magnetic resonance imaging (n = 42). Early-life exposure to PCE was estimated using a leaching and transport model. The data analysis compared the occurrence of each health outcome among individuals with prenatal and early childhood PCE exposure to unexposed individuals while considering the effect of confounding variables.

FINDINGS

The study found evidence that early-life exposure to PCE-contaminated drinking water has long-term neurotoxic effects. The strongest associations were seen with illicit drug use, bipolar disorder, and post-traumatic stress disorder. Key strengths of the study were availability of historical data on affected water systems, a relatively high exposure prevalence and wide range of exposure levels, and little confounding. Challenges arose mainly from the historical nature of the exposure assessments.

CONCLUSIONS

The Cape Cod Health Study demonstrates how scientists can take advantage of unique "natural experiments" to learn about the health effects of environmental pollution. This body of work has improved our understanding of the long-term health effects of early-life exposure to this common environmental contaminant and will help risk assessors and policymakers ensure that drinking water supplies in the United States are safe for vulnerable populations.

Childhood Fish Consumption and Learning and Behavioral Disorders

Fish is a major source of nutrients critical for brain development during early life. The importance of childhood fish consumption is supported by several studies reporting associations of n-3 polyunsaturated fatty acid (n-3 PUFA) supplementation with better behavior and school performance. However, fish may have a different effect than n-3 PUFA alone due to the neurotoxic effects of methylmercury, a frequent contaminant. We investigated associations of childhood fish consumption with learning and behavioral disorders in birth cohort study of the neurotoxic effects of early life exposure to solvent-contaminated drinking water. Childhood (age 7–12 years) fish consumption and learning and behavioral problems were reported in self-administered questionnaires (age 23–41 at questionnaire completion). Fish consumption was not meaningfully associated with repeating a grade, tutoring, attending summer school, special class placement, or low educational attainment. However, participants who ate fish several times a week had an elevated odds of Attention Deficit Disorder/Attention Deficit Hyperactivity Disorder (odds ratio: 5.2; 95% confidence interval: 1.5–18) compared to participants who did not eat fish. While these findings generally support the safety of the observed level of fish consumption, the absence of a beneficial effect may be attributed to insufficient fish intake or the choice of relatively low n-3 PUFA fish.

Association of prenatal and early life exposure to tetrachloroethylene (PCE) with polycystic ovary syndrome and other reproductive disorders in the cape cod health study: A retrospective cohort study

BACKGROUND

Tetrachloroethylene (PCE) is an organic lipophilic solvent with possible neuroendocrine toxicity. The objective of this study was to determine the association of prenatal and early childhood exposure to PCE-contaminated drinking water and development of adult-onset Polycystic Ovary Syndrome (PCOS), endometriosis, difficulty conceiving and miscarriage.

METHODS

Five-hundred exposed and 331 unexposed female participants born between 1969 and 1983 completed questionnaires on demographic and lifestyle characteristics, and reproductive disorders. Residential locations from the prenatal period through five years of age were used to estimate early life PCE exposure with water modeling software.

RESULTS

For any early life exposure to PCE, the adjusted risk ratio for PCOS was 0.9 (95% CI: 0.5-1.6). No statistically significant associations were observed for increasing levels of exposure with PCOS or the other reproductive disorders.

CONCLUSION

No meaningful associations were found among adult women with early life exposure to PCE-contaminated drinking water and adult-onset reproductive disorders.

Long-term health effects of early life exposure to tetrachloroethylene (PCE)-contaminated drinking water: a retrospective cohort study

BACKGROUND

While adult exposure to PCE is known to have toxic effects, there is little information on the long-term impact of prenatal and early childhood exposure. We undertook a retrospective cohort study to examine the effects of their early life exposure to PCE-contaminated drinking water. This retrospective cohort study examined whether prenatal and early childhood exposure to PCE-contaminated drinking water influenced the risk of a variety of chronic conditions among adults who were born between 1969 and 1983 in the Cape Cod area of Massachusetts.

METHODS

Eight hundred and thirty-one participants with prenatal and early childhood PCE exposure and 547 unexposed participants were studied. Individuals completed questionnaires to gather information on demographic characteristics, chronic conditions, and other sources of solvent exposure. The location of residences from birth through 1990 were used to estimate PCE exposure with U.S. EPA's water distribution system modeling software (EPANET) modified to incorporate a leaching and transport model.

RESULTS

No associations were observed between early life PCE exposure and current occurrence of obesity, diabetes, cardiovascular disease, hypertension, color blindness, near- and far sightedness and dry eyes. In contrast, a 1.8-fold increased risk of cancer (95% CI: 0.8, 4.0) was seen among individuals with any early life exposure. These results were based on 31 participants (23 exposed and 8 unexposed) who reported cancers at a variety of anatomical sites, particularly the cervix. A 1.5-fold increase in the risk of epilepsy (95% CI: 0.6, 3.6, based on 16 exposed and 7 unexposed participants) was also observed among individuals with any early life exposure that was further increased to 1.8 (95% CI: 0.7, 4.6) among those with exposure at or above the sample median.

CONCLUSIONS

These results suggest that the risk of epilepsy and certain types of cancer such as cervical cancer may be increased among adults who were exposed to PCE-contaminated drinking water exposure during gestation and early childhood. These findings should be interpreted cautiously because of the study limitations and confirmed in follow-up investigations of similarly exposed populations with medically-confirmed diagnoses. This relatively young study population should also be monitored periodically for subsequent changes in disease risk.

Retinal and visual system: occupational and environmental toxicology

Occupational chemical exposure often results in sensory systems alterations that occur without other clinical signs or symptoms. Approximately 3000 chemicals are toxic to the retina and central visual system. Their dysfunction can have immediate, long-term, and delayed effects on mental health, physical health, and performance and lead to increased occupational injuries. The aims of this chapter are fourfold. First, provide references on retinal/visual system structure, function, and assessment techniques. Second, discuss the retinal features that make it especially vulnerable to toxic chemicals. Third, review the clinical and corresponding experimental data regarding retinal/visual system deficits produced by occupational toxicants: organic solvents (carbon disulfide, trichloroethylene, tetrachloroethylene, styrene, toluene, and mixtures) and metals (inorganic lead, methyl mercury, and mercury vapor). Fourth, discuss occupational and environmental toxicants as risk factors for late-onset retinal diseases and degeneration. Overall, the toxicants altered color vision, rod- and/or cone-mediated electroretinograms, visual fields, spatial contrast sensitivity, and/or retinal thickness. The findings elucidate the importance of conducting multimodal noninvasive clinical, electrophysiologic, imaging and vision testing to monitor toxicant-exposed workers for possible retinal/visual system alterations. Finally, since the retina is a window into the brain, an increased awareness and understanding of retinal/visual system dysfunction should provide additional insight into acquired neurodegenerative disorders.

Human health effects of tetrachloroethylene: key findings and scientific issues

BACKGROUND

The U.S. Environmental Protection Agency (EPA) completed a toxicological review of tetrachloroethylene (perchloroethylene, PCE) in February 2012 in support of the Integrated Risk Information System (IRIS).

OBJECTIVES

We reviewed key findings and scientific issues regarding the human health effects of PCE described in the U.S. EPA's Toxicological Review of Tetrachloroethylene (Perchloroethylene).

METHODS

The updated assessment of PCE synthesized and characterized a substantial database of epidemiological, experimental animal, and mechanistic studies. Key scientific issues were addressed through modeling of PCE toxicokinetics, synthesis of evidence from neurological studies, and analyses of toxicokinetic, mechanistic, and other factors (tumor latency, severity, and background rate) in interpreting experimental animal cancer findings. Considerations in evaluating epidemiological studies included the quality (e.g., specificity) of the exposure assessment methods and other essential design features, and the potential for alternative explanations for observed associations (e.g., bias or confounding).

DISCUSSION

Toxicokinetic modeling aided in characterizing the complex metabolism and multiple metabolites that contribute to PCE toxicity. The exposure assessment approach-a key evaluation factor for epidemiological studies of bladder cancer, non-Hodgkin lymphoma, and multiple myeloma-provided suggestive evidence of carcinogenicity. Bioassay data provided conclusive evidence of carcinogenicity in experimental animals. Neurotoxicity was identified as a sensitive noncancer health effect, occurring at low exposures: a conclusion supported by multiple studies. Evidence was integrated from human, experimental animal, and mechanistic data sets in assessing adverse health effects of PCE.

CONCLUSIONS

PCE is likely to be carcinogenic to humans. Neurotoxicity is a sensitive adverse health effect of PCE.

Limited representation of drinking-water contaminants in pregnancy-birth cohorts

Water contamination and noise have been consistently the least assessed environmental/lifestyle exposures in pregnancy-birth cohorts (PBC). Water quality surveillance data collected during the past decade within urban drinking-water distribution systems call for re-evaluation of water and health issues in the developed world. The objectives of this scientific commentary were to (i) highlight the extent of appraisal of water contamination in exposure assessment studies of PBC, worldwide, and (ii) propose recommendations to increase awareness of emerging water-related risks through their improved representation into PBC study designs in urban centers. Three scientific literature databases (Scopus, PubMed, and Web of Science) were used for a systematic search on worldwide PBC and their publications that considered water contamination and health outcomes. Publicly-available e-databases (ENRIECO, BIRTHCOHORTS, and CHICOS) were also employed for detailed exploration of existing European Union (EU)-based PBC. Out of the 76 PBC identified in the EU territory, only 12 of them incorporated water contamination into their study designs. Among which only 6 PBC published scientific articles that either included data on water contamination and/or water intake estimates. Trihalomethanes but not other disinfection by-products were mostly studied in the PBC around the globe, while fluoride, atrazine, perfluorinated compounds, tetrachloroethylene, and lead were studied to a lesser extent as water contaminants. It appears that chemical-based water contamination and corresponding human exposures represent a largely underappreciated niche of exposure science pertaining to pregnant mother and children's health in PBC. Future PBC studies should grasp this opportunity to substantially reform elements of water contamination in their exposure assessment protocols and effectively combine them with their epidemiological study designs.

Structural Magnetic Resonance Imaging in an adult cohort following prenatal and early postnatal exposure to tetrachloroethylene (PCE)-contaminated drinking water

This population-based retrospective cohort study examined Structural Magnetic Resonance Imaging (MRI) of the brain in relation to prenatal and early postnatal exposure to tetrachloroethylene (PCE)-contaminated drinking water on Cape Cod, Massachusetts. Subjects were identified through birth records from 1969 through 1983. Exposure was modeled using pipe network information from town water departments, a PCE leaching and transport algorithm, EPANet water flow modeling software, and Geographic Information System (GIS) methodology. Brain imaging was performed on 26 exposed and 16 unexposed subjects. Scans were acquired on a Philips 3T whole body scanner using the ADNI T1-weighted MP-RAGE scan. The scans were processed by FreeSurfer version 4.3.1 software to obtain measurements of specific brain regions. There were no statistically significant differences between exposed and unexposed subjects on the measures of white matter hypointensities (β: 127.5mm(3), 95% CI: -259.1, 1514.0), white matter volumes (e.g. total cerebral white matter: β: 21230.0mm(3), 95% CI: -4512.6, 46971.7) or gray matter volumes (e.g. total cerebral gray matter: β: 11976.0mm(3), 95% CI: -13657.2, 37609.3). The results of this study suggest that exposure to PCE during gestation and early childhood, at the levels observed in this population, is not associated with alterations in the brain structures studied.