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Conditional means regression, including ordinary least squares (OLS), provides an incomplete picture of exposure-response relationships particularly if the primary interest resides in the tail ends of the distribution of the outcome. Quantile regression (QR) offers an alternative methodological approach in which the influence of independent covariates on the outcome can be specified at any location along the distribution of the outcome. We implemented QR to examine heterogeneity in the influence of early childhood lead exposure on reading and math standardized fourth grade tests. In children from two urban school districts (n=1,076), lead exposure was associated with an 18.00 point decrease (95% CI: -48.72, -3.32) at the 10th quantile of reading scores, and a 7.50 point decrease (95% CI: -15.58, 2.07) at the 90th quantile. Wald tests indicated significant heterogeneity of the coefficients across the distribution of quantiles. Math scores did not show heterogeneity of coefficients, but there was a significant difference in the lead effect at the 10th (β=-17.00, 95% CI: -32.13, -3.27) versus 90th (β=-4.50, 95% CI: -10.55, 4.50) quantiles. Our results indicate that lead exposure has a greater effect for children in the lower tail of exam scores, a result that is masked by conditional means approaches., (Copyright © 2014 Elsevier Inc. All rights reserved.)

School suspensions are associated with negative student outcomes. Environmental lead exposure increases hyperactivity and sensory defensiveness, two traits likely to increase classroom misbehavior and subsequent discipline. Childhood Blood Lead Level (BLL) test results categorized urban fourth graders as exposed (2687; lifetime max BLL 10-20 µg/dL) or unexposed (1076; no lifetime BLL ≥5 µg/dL). Exposed children were over twice as likely as unexposed children to be suspended (OR=2.66, 95% CI=[2.12, 3.32]), controlling for covariates. African American children were more likely to be suspended than white children, but lead exposure explained 23% of the racial discipline gap. These results suggest that different rates of environmental lead exposure may contribute to the racial discipline gap., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Purpose: There are different mineral classes of asbestos, including serpentines and amphiboles. Chrysotile is the main type of serpentine and by far the most frequently used type of asbestos (about 95% of world production and use). There has been continuing controversy over the capability of chrysotile asbestos to cause pleural and peritoneal mesothelioma. This review is to help clarify the issue by detailing cases and epidemiology studies worldwide where chrysotile is the exclusive or overwhelming fiber exposure., Methods: A worldwide literature review was conducted of asbestos and associated mesothelioma including case series, case-control and cohort epidemiology studies searching for well documented chrysotile asbestos associated mesothelioma cases., Results: Chrysotile asbestos exposures have occurred in many countries around the world from mining, manufacturing and community exposures. There have been many documented cases of mesothelioma from those exposures., Conclusions: Chrysotile asbestos, along with all other types of asbestos, has caused mesothelioma and a world-wide ban of all asbestos is warranted to stop an epidemic of mesothelioma., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Research has suggested possible human health effects from low-level widespread exposure to environmental contaminants. We employed a novel exposure estimation technique using a publicly available data set to examine atrazine exposure, a suspected endocrine disruptor, in relation to breast cancer risk for women living in rural areas of Wisconsin. Incident breast cancer cases who were 20-79 years of age from 1987 to 2000 (n=3,275) and living in rural areas of Wisconsin at the time of interview were identified from Wisconsin's statewide cancer registry. Female controls of similar age and living in rural areas of Wisconsin were randomly selected from population lists (n=3,669). The addresses at diagnosis or reference year of study participants were assigned latitude/longitude coordinates (geocoded). The results from three statewide random studies of atrazine levels in well water in 1994, 1996, and 2001 were obtained from the Wisconsin Department of Agriculture, Trade, and Consumer Protection. Natural neighbor interpolation was used to estimate atrazine exposure levels separately for each of the 3 years. The mean atrazine exposure level was assigned to each participant based on her geocode. After adjustment for established breast cancer risk factors, compared to women in the lowest category of atrazine exposure (<0.15 ppb), the odds ratio of breast cancer for women exposed to atrazine concentrations of 1.0-2.9 ppb was 1.1 (95% CI 0.9-1.4). Results from this large population-based study do not suggest an increased risk of breast cancer from adult exposure to atrazine in drinking water. The possible risk for women exposed to levels of atrazine at or above statutory action levels of >or=3 ppb (OR 1.3, 95% CI 0.3-6.5) could not be ruled out due to small numbers in this category.

This is the third and final paper in a series about nanomaterials and their potential health effects. There has been an incident of apparent respiratory health effects in Germany in consumers using a "nano" cleaning product. Other recently proposed consumer products seem to carry potential health and/or ecological hazards. In light of rapidly evolving nanotechnology the "precautionary principle" in environmental health science is reviewed. Hopefully a balance can be reached that allows the realization of societal benefits from the development and implementation of nanotechnology while preventing its unquestioned use in ways that damage ecology and human health.

In this paper, we summarize some of the key data gaps, uncertainties, and unknowns that need to be addressed to develop adequate risk assessments for nanomaterials. We make recommendations to take timely and appropriate public health precautions. We also briefly discuss nanotechnology applications for food and food packaging, and describe the University of Wisconsin-Madison's Nanotechnology in Society Project.

Nanotechnologies are among the fastest growing areas of scientific research, and have important applications in a wide variety of fields. At the same time, scientists and regulators are concerned about the potential health and environmental risks related to the widespread production and use of the nanomaterials created by these technologies. Several recent animal and cell culture studies have suggested that some engineered nanomaterials may have biological effects similar to ultrafine particulates. This paper describes what nanomaterials are and why they might be toxic, and then reviews existing toxicological studies on engineered nanomaterials.

There is ever increasing concern whether potentially toxic environmental conditions are adversely impacting the health of the human population at risk of exposure. Traditional methods of epidemiology and other health related research disciplines have the reverse orientation, as they start with the occurrence of an epidemic, or a certain rate of disease in the population, and then seek the causes of that disease incidence. Traditional study designs offer much in the methods of disease/epidemic investigation, but less is available in the methods of exposure investigation. An introductory outline is offered here detailing the nature of the steps to be taken and their rationale in consideration of the health consequences of an environmental exposure.