Quantile regression in environmental health: Early life lead exposure and end-of-grade exams.

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 (ß=-17.00, 95% CI: -32.13, -3.27) versus 90th (ß=-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.

Early lead exposure (<3 years old) prospectively predicts fourth grade school suspension in Milwaukee, Wisconsin (USA).

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.

Urinary lead level and colonization by antibiotic resistant bacteria: Evidence from a population-based study.

BACKGROUND: Infection by antibiotic resistant bacteria (ARB) is a global health crisis and asymptomatic colonization increases risk of infection. Nonhuman studies have linked heavy metal exposure to the selection of ARB; however, few epidemiologic studies have examined this relationship. This study analyzes the association between urinary lead level and colonization by ARB in a nonclinical human population. METHODS: Data came from the Survey of the Health of Wisconsin 2016-2017, and its ancillary Wisconsin Microbiome Study. Urinary lead levels, adjusted for creatinine, were used to assess exposure. ARB included methicillin resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), fluoroquinolone resistant Gram-negative bacilli (RGNB), and Clostridium difficile (C. diff), from skin, nose, and mouth swabs, and saliva and stool samples. Logistic regression, adjusted for covariates, was used to evaluate associations between Pb and ARB. Secondary analysis investigated Pb resistance from ARB isolates. RESULTS: Among 695 participants, 239 (34%) tested positive for ARB. Geometric mean urinary Pb (unadjusted) was 0.286 µg/L (95% confidence intervals [CI] = 0.263, 0.312) for ARB negative participants and 0.323 µg/L (95% CI = 0.287, 0.363) for ARB positive participants. Models adjusted for demographics, diet, and antibiotic use showed elevated odds of positive colonization for those in the 95th percentile (vs. below) of Pb exposure (odds ratio [OR] = 2.05, 95% CI = 0.95, 4.44), and associations were highest in urban residents (OR = 2.85, 95% CI = 1.07, 7.59). RGNB isolates were most resistant to Pb. DISCUSSION: These novel results suggest that Pb exposure is associated with increased colonization by ARB, and that RGNB are particularly resistant to Pb.

Bicycling Rates and the Prevalence of Bicycle Helmet Usage in Wisconsin.

INTRODUCTION: Bicycles are a source of transportation, recreation, and exercise throughout the world. Bicycling is associated with both health and environmental benefits but also poses a risk of injury. The use of bicycle helmets has been shown to reduce morbidity and mortality associated with cycling. It is unknown if helmet use differs across Wisconsin geographic areas and sociodemographic groups. METHODS: Data were obtained from the Survey of the Health of Wisconsin (SHOW). Bicycle use and helmet use frequency were determined from a self-administered questionnaire that contained questions specific to preventative health behaviors. Descriptive statistics summarized overall bicycle ridership. Chi-square and Student t tests were performed to assess relationships between bicycle and helmet use across geographic categories and sociodemographic groups. RESULTS: Differences between sex, race or ethnicity, and education level were found to be associated with bicycle ridership and the frequency of helmet use. Men were significantly more likely to report riding a bicycle and never wearing a helmet. Individuals from urban communities reported always wearing a helmet more often than rural communities. Higher education levels were associated with higher levels of bicycle and helmet use. Race or ethnicity was not associated with bicycle ridership but was associated with differences in helmet use frequency. CONCLUSION: Nearly half of those who ride bicycles in Wisconsin report never wearing a helmet. Since bicycle ridership and helmet use were found to be associated with a number of sociodemographic characteristics, any solution should consider the role of equity when attempting to increase ridership or helmet use.

Factors associated with the seasonality of blood lead levels among preschool Wisconsin children.

CONTEXT: Aggregate blood lead testing data for Wisconsin children younger than age 6 exhibit seasonal trends in both average blood lead levels and in the percent of those tested and found to have blood lead levels in excess of the 10 mcg/dL threshold for poisoning. Blood lead levels and poisoning rates typically peak during the late summer and early fall months, and are at their minimum during the late winter. METHOD: Blood test data was analyzed to determine variations by month and age. RESULTS: Seasonal variations are evident even among the very young: infants younger than 10 months who likely have limited opportunity to encounter lead hazards within their home or in the outdoor soil. Seasonal periodicity is most evident among infants who reside in very urban and very rural communities. The observed seasonal periodicity might be associated with the seasonal availability of lead within the children's environment. Particulate matter data measured at several ambient air quality monitoring stations exhibit a similar periodic seasonality, suggesting a possible relationship between blood lead levels and the availability of dust and airborne particulates during the summer months. CONCLUSION: Clinicians should consider the seasonality of blood lead levels when scheduling tests and interpreting test results.

Nitrogen-nitrate exposure from drinking water and colorectal cancer risk for rural women in Wisconsin, USA.

One unintentional result of widespread adoption of nitrogen application to croplands over the past 50 years has been nitrate contamination of drinking water with few studies evaluating the risk of colorectal cancer. In our population-based case-control study of 475 women age 20-74 years with colorectal cancer and 1447 community controls living in rural Wisconsin, drinking water nitrate exposure were interpolated to subjects residences based on measurements which had been taken as part of a separate water quality survey in 1994. Individual level risk factor data was gathered in 1990-1992 and 1999-2001. Logistic regression models estimated the risk of colorectal cancer for the study period, separately and pooled. In the pooled analyses, an overall colorectal cancer risk was not observed for exposure to nitrate-nitrogen in the highest category (> or =10 ppm) compared to the lowest category (<0.5 ppm). However, a 2.9 fold increase risk was observed for proximal colon cancer cases in the highest compared to the lowest category. Statistically significant increased distal colon or rectal cancer risk was not observed. These results suggest that if an association exists with nitrate-nitrogen exposure from residential drinking water consumption, it may be limited to proximal colon cancer.

Nanomaterial health effects part 3: conclusion--hazardous issues and the precautionary principle.

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.

Nanomaterial health effects--part 1: background and current knowledge.

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.

Nanomaterial health effects--Part 2: Uncertainties and recommendations for the future.

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.

Potential exposure to PCBs, DDT, and PBDEs from sport-caught fish consumption in relation to breast cancer risk in Wisconsin.

In Wisconsin, consumption of Great Lakes fish is an important source of exposure to polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), polybrominated diphenyl ethers (PBDEs), and other halogenated hydrocarbons, all of which may act as potential risk factors for breast cancer. We examined the association between sport-caught fish consumption and breast cancer incidence as part of an ongoing population-based case-control study. We identified breast cancer cases 20-69 years of age who were diagnosed in 1998-2000 (n = 1,481) from the Wisconsin Cancer Reporting System. Female controls of similar age were randomly selected from population lists (n = 1,301). Information about all sport-caught (Great Lakes and other lakes) fish consumption and breast cancer risk factors was obtained through telephone interviews. After adjustment for known and suspected risk factors, the relative risk of breast cancer for women who had recently consumed sport-caught fish was similar to women who had never eaten sport-caught fish [relative risk (RR) = 1.00; 95% confidence interval (CI), 0.86-1.17]. Frequency of consumption and location of sport-caught fish were not associated with an increased risk of breast cancer. Recent consumption of Great Lakes fish was not associated with postmenopausal breast cancer (RR = 0.78; 95% CI, 0.57-1.07), whereas risk associated with premenopausal breast cancer was elevated (RR = 1.70; 95% CI, 1.16-2.50). In this study we found no overall association between recent consumption of sport-caught fish and breast cancer, although there may be an increased breast cancer risk for subgroups of women who are young and/or premenopausal.

Moderate lead exposure and elementary school end-of-grade examination performance.

PURPOSE: This study investigated the association between moderate lead poisoning in early childhood with performance on a comprehensive set of end-of-grade examinations at the elementary school level in two urban school districts. METHODS: Children born between 1996 and 2000 who resided in Milwaukee or Racine, WI, with a record of a blood lead test before the age of 3 years were considered for the analysis. Children were defined as exposed (blood lead level ≥10 and <20 µg/dL) or not exposed (BLL < 5 µg/dL). Parents of eligible children were mailed surveys to consent to participation and elicit information on potential confounders. On consent, children were matched to educational records for fourth grade Wisconsin Knowledge and Concepts Examinations. Seemingly unrelated regression was used to evaluate the relation between scaled scores on all sections of the examination (math, reading, language arts, science, and social studies) with exposure status, controlling for demographics, social status indicators, health indicators, and district-based poverty indicators. RESULTS: A total of 1133 families responded to the survey and consented to have educational records released; 43% of children were considered exposed. After controlling for demographic and socioeconomic covariates, lead exposure was associated with significantly lower scores in all sections of the Wisconsin Knowledge and Concepts Examinations (range: science, ß = -5.21, P = .01; reading, ß = -8.91, P = .003). Children who were black, had a parent with less than a high-school education, and were classified by parents as having less than excellent health had significantly lower performance on all examination components. CONCLUSIONS: Children with moderate lead poisoning in early childhood performed significantly lower on all components of elementary school end-of-grade examinations compared with unexposed children. Household level social status and childhood health indicators partially explain decreased examination scores.

Removing barriers to participation in clinical trials, a conceptual framework and retrospective chart review study.

BACKGROUND: Enrollment in interventional therapeutic clinical trials is a small fraction of all patients who might participate given reasonable access. METHODS: A hierarchical approach is utilized in measuring staged participation from trial availability to patient enrollment. Our framework suggests that concern for justice comes in the design and eligibility criteria for clinical trials; attention to beneficence is given in the eligibility and physician triage stages. The remaining four stages rely on respect for persons. An example is given where reasons for nonparticipation or barriers to participation in prostate cancer clinical trials are examined within the framework. In addition, medical oncology patients with an initial six month consultation are tracked from one stage to the next by race using the framework to assess participation comparability. RESULTS: We illustrated seven transitions from being a patient to enrollment in a clinical trial in a small study of prostate cancer cases who consulted SKCCC Medical Oncology Department in early 2010. Pilot data suggest transition probabilities as follows: 65% availability, 84% eligibility, 92% patient triage, 89% trials discussed, 45% patient interested, 63% patient consented, and 92% patient enrolled. The average transition probability was 77.7%. The average transition probability, patient-trial-fit was 50%; opportunity was 51%, and acceptance was 66.7%. Trial availability, patient interest and patient consented were three transitions that were below the average; none were statistically significant. CONCLUSIONS: The framework may serve to streamline comprehensive reporting of clinical trial participation to the benefit of patients and the ethical conduct of clinical trials.

Lead exposure and educational proficiency: moderate lead exposure and educational proficiency on end-of-grade examinations.

PURPOSE: To investigate and quantify the impact of moderate lead exposure on students' ability to score at the "proficient" level on end-of-grade standardized tests. METHODS: We compared the scores of 3757 fourth grade students from Milwaukee, Wisconsin, on the Wisconsin Knowledge and Concepts Exam (WKCE). The sample consisted of children with a blood lead test before age 3 years that was either unquantifiable at the time of testing (<5 µg/dL) or in the range of moderate exposure (10-19 µg/dL). RESULTS: After controlling for gender, poverty, English language learner status, race/ethnicity, school disciplinary actions, and attendance percentage, results showed a significant negative effect of moderate lead exposure on academic achievement for all 5 subtests of the WKCE. Test score deficits owing to lead exposure were equal to 22% of the interval between student categorization at the "proficient" or "basic" levels in Reading, and 42% of the interval in Mathematics. CONCLUSIONS: Children exposed to amounts of lead before age 3 years that are insufficient to trigger intervention under current policies in many states are nonetheless at a considerable educational disadvantage compared with their unexposed peers 7 to 8 years later. Exposed students are at greater risk of scoring below the proficient level, an outcome with serious negative consequences for both the student and the school.

Mesothelioma from chrysotile asbestos: update.

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.

Risk of breast cancer for women living in rural areas from adult exposure to atrazine from well water in Wisconsin.

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.

Tuberculosis cases in Wisconsin: documentation of treatment improvement and completion of treatment, 2000-2002.

OBJECTIVE: In 2000, the Wisconsin Strategic Plan for the Elimination of Tuberculosis (TB) sets goals of 90 percent treatment completion and 95 percent documentation of treatment improvement for all reported cases of TB. This study measures the success in achieving these goals. METHODS: Data were abstracted from charts of all 249 reported TB cases during 2000-2002. Treatment completion was considered for patients indicated for completion in 12 months or less. Documentation of treatment improvement included therapy adherence, sputum culture conversion, and chest radiograph improvement for pulmonary cases, and therapy adherence and clinical improvement for extrapulmonary cases. RESULTS: Treatment completion was measured in 204 of 249 TB cases; 87.1 percent completed treatment in 12 months or less. There was a significant difference in completion by site of disease, 89.9 percent for pulmonary cases and 66.1 percent for extrapulmonary cases (P < .01). Documentation of treatment improvement was 61.2 percent among pulmonary cases and 83.6 percent among extrapulmonary cases (P < .01). During the study period, there was a significant decrease in documentation rates for patients with pulmonary TB (P < .01). CONCLUSIONS: The goal of 90 percent treatment completion was nearly accomplished but the goal of 95 percent documentation of treatment improvement was not achieved. Barriers to TB treatment in Wisconsin need to be identified. Case management of TB is necessary for control and prevention of TB.

Maternal exposure to Great Lakes sport-caught fish and dichlorodiphenyl dichloroethylene, but not polychlorinated biphenyls, is associated with reduced birth weight.

Fish consumption may be beneficial for a developing human fetus, but fish may also contain contaminants that could be detrimental. Great Lakes sport-caught fish (GLSCF) are contaminated with polychlorinated biphenyls (PCBs) and dichlorodiphenyl dichloroethylene (DDE), but the effects of these contaminants on birth outcome are not clear. To distinguish potential contaminant effects, we examined (1) whether the decrease over time in contaminant levels in GLSCF is paralleled by an increase in birth weight of children of GLSCF-consuming mothers and (2) the relation between maternal serum concentrations of these contaminants and birth weight. Mothers (n=511) were interviewed from 1993 to 1995, and maternal serum was collected from 1994 to 1995 (n=143). Potential confounders considered were child gender, maternal age at delivery, maternal prepregnancy body mass index, maternal cigarette and alcohol use during pregnancy, maternal education level, maternal parity, and maternal breastfeeding. Children born during 1970-1977, 1978-1984, and 1985-1993 to mothers who ate more than 116 meals of GLSCF before pregnancy were, on average, 164 g lighter, 46 g heavier, and 134 g heavier, respectively, than children of mothers who ate no GLSCF before pregnancy (P trend=0.05). GLSCF-consuming mothers had higher serum PCB and DDE concentrations, but only increased DDE was associated with lower birth weight. The data suggest that fetal DDE exposure (as indicated by maternal serum DDE concentration) may decrease birth weight and that decreased birth weight effects associated with GLSCF consumption have decreased over time.