Paul English

The 2006 California heat wave: impacts on hospitalizations and emergency department visits.

Background Climate models project that heat waves will increase in frequency and severity. Despite many studies of mortality from heat waves, few studies have examined morbidity. Objectives In this study we investigated whether any age or race/ethnicity groups experienced increased hospitalizations and emergency department (ED) visits overall or for selected illnesses during the 2006 California heat wave. Methods We aggregated county-level hospitalizations and ED visits for all causes and for 10 cause groups into six geographic regions of California. We calculated excess morbidity and rate ratios (RRs) during the heat wave (15 July to 1 August 2006) and compared these data with those of a reference period (8–14 July and 12–22 August 2006). Results During the heat wave, 16,166 excess ED visits and 1,182 excess hospitalizations occurred statewide. ED visits for heat-related causes increased across the state [RR = 6.30; 95% confidence interval (CI), 5.67–7.01], especially in the Central Coast region, which includes San Francisco. Children (0–4 years of age) and the elderly (≥ 65 years of age) were at greatest risk. ED visits also showed significant increases for acute renal failure, cardiovascular diseases, diabetes, electrolyte imbalance, and nephritis. We observed significantly elevated RRs for hospitalizations for heat-related illnesses (RR = 10.15; 95% CI, 7.79–13.43), acute renal failure, electrolyte imbalance, and nephritis. Conclusions The 2006 California heat wave had a substantial effect on morbidity, including regions with relatively modest temperatures. This suggests that population acclimatization and adaptive capacity influenced risk. By better understanding these impacts and population vulnerabilities, local communities can improve heat wave preparedness to cope with a globally warming future.

Maternal Residence Near Agricultural Pesticide Applications and Autism Spectrum Disorders among Children in the California Central Valley

Background Ambient levels of pesticides (“pesticide drift”) are detectable at residences near agricultural field sites. Objective Our goal was to evaluate the hypothesis that maternal residence near agricultural pesticide applications during key periods of gestation could be associated with the development of autism spectrum disorders (ASD) in children. Methods We identified 465 children with ASD born during 1996–1998 using the California Department of Developmental Services electronic files, and matched them by maternal date of last menstrual period to 6,975 live-born, normal-birth-weight, term infants as controls. We determined proximity to pesticide applications using California Department of Pesticide Regulation records refined using Department of Water Resources land use polygons. A staged analytic design applying a priori criteria to the results of conditional logistic regressions was employed to exclude associations likely due to multiple testing error. Results Of 249 unique hypotheses, four that described organochlorine pesticide applications—specifically those of dicofol and endosulfan—occurring during the period immediately before and concurrent with central nervous system embryogenesis (clinical weeks 1 through 8) met a priori criteria and were unlikely to be a result of multiple testing. Multivariate a posteriori models comparing children of mothers living within 500 m of field sites with the highest nonzero quartile of organochlorine poundage to those with mothers not living near field sites suggested an odds ratio for ASD of 6.1 (95% confidence interval, 2.4–15.3). ASD risk increased with the poundage of organochlorine applied and decreased with distance from field sites. Conclusions The association between residential proximity to organochlorine pesticide applications during gestation and ASD among children should be further studied.

Nitrogen dioxide prediction in Southern California using land use regression modeling: potential for environmental health analyses.

We modeled the intraurban distribution of nitrogen dioxide (NO2), a marker for traffic pollution, with land use regression, a promising new exposure classification technique. We deployed diffusion tubes to measure NO2 levels at 39 locations in the fall of 2003 in San Diego County, CA, USA. At each sample location, we constructed circular buffers in a geographic information system and captured information on roads, traffic flow, land use, population and housing. Using multiple linear regression, we were able to predict 79% of the variation in NO2 levels with four variables: traffic density within 40–300 m of the sampling location, traffic density within 300–1000 m, length of road within 40 m and distance to the Pacific coast. Applying this model to validation samples showed that the model predicted NO2 levels within, on average, 2.1 p.p.b for 12 training sites initially excluded from the model.Our evaluation of this land use regression model showed that this method had excellent prediction and robustness in a North American context. These models may be useful tools in evaluating health effects of long-term exposure to traffic-related pollution.

Evaluation of a Heat Vulnerability Index on Abnormally Hot Days: An Environmental Public Health Tracking Study

Background: Extreme hot weather conditions have been associated with increased morbidity and mortality, but risks are not evenly distributed throughout the population. Previously, a heat vulnerability index (HVI) was created to geographically locate populations with increased vulnerability to heat in metropolitan areas throughout the United States. Objectives: We sought to determine whether areas with higher heat vulnerability, as characterized by the HVI, experienced higher rates of morbidity and mortality on abnormally hot days. Methods: We used Poisson regression to model the interaction of HVI and deviant days (days whose deviation of maximum temperature from the 30-year normal maximum temperature is at or above the 95th percentile) on hospitalization and mortality counts in five states participating in the Environmental Public Health Tracking Network for the years 2000 through 2007. Results: The HVI was associated with higher hospitalization and mortality rates in all states on both normal days and deviant days. However, associations were significantly stronger (interaction p-value < 0.05) on deviant days for heat-related illness, acute renal failure, electrolyte imbalance, and nephritis in California, heat-related illness in Washington, all-cause mortality in New Mexico, and respiratory hospitalizations in Massachusetts. Conclusion: Our results suggest that the HVI may be a marker of health vulnerability in general, although it may indicate greater vulnerability to heat in some cases.

Environmental health indicators of climate change for the United States: findings from the state environmental health indicator collaborative.

Objective To develop public health adaptation strategies and to project the impacts of climate change on human health, indicators of vulnerability and preparedness along with accurate surveillance data on climate-sensitive health outcomes are needed. We researched and developed environmental health indicators for inputs into human health vulnerability assessments for climate change and to propose public health preventative actions. Data sources We conducted a review of the scientific literature to identify outcomes and actions that were related to climate change. Data sources included governmental and nongovernmental agencies and the published literature. Data extraction Sources were identified and assessed for completeness, usability, and accuracy. Priority was then given to identifying longitudinal data sets that were applicable at the state and community level. Data synthesis We present a list of surveillance indicators for practitioners and policy makers that include climate-sensitive health outcomes and environmental and vulnerability indicators, as well as mitigation, adaptation, and policy indicators of climate change. Conclusions A review of environmental health indicators for climate change shows that data exist for many of these measures, but more evaluation of their sensitivity and usefulness is needed. Further attention is necessary to increase data quality and availability and to develop new surveillance databases, especially for climate-sensitive morbidity.

Parental and birth characteristics in relation to testicular cancer risk among males born between 1960 and 1995 in California (United States)

Objective: We explored birth and parental risk factors for testicular cancer, examining risk factors for all testicular cancers and by histologic type. Methods: We linked 1645 testicular cancer cases to live singleton birth certificates, selecting three random controls per case, matched by sex and date of birth. We used conditional multiple logistic regression to assess the mutually adjusted effects of parental and birth characteristics on testicular cancer risk. Results: Sons of Black mothers had a lower risk than those of White mothers (adjusted odds ratio (AOR) = 0.38, 95% confidence interval (CI) = 0.12, 1.22). Increasing maternal age was associated with an increased risk in offspring (AOR = 1.03 for each year of maternal age, 95% CI = 1.01, 1.05). Sons of primiparous and low-multiparous women had increased risks compared to sons of high-multiparous women (AOR = 1.22, 95% CI = 1.04, 1.44; and AOR = 1.31, 95% CI = 1.12, 1.54, respectively). Among seminomas, term infants with birth weights of 1500–2499g had a higher risk compared to term, normal birth weight infants (AOR = 2.69, 95% CI = 1.40, 5.17; p-value for homogeneity = 0.008). Conclusions: Markers of higher estrogen exposure in the mother (age and parity) are associated with increased testicular cancer risk, and factors associated with fetal growth retardation may be associated with seminoma testicular cancer.

Physical exertion as a risk factor for spontaneous abortion.

This study examined the association of physical exertion and spontaneous abortion in a case-control study of 607 women whose pregnancies ended in spontaneous abortion and 1,287 women who delivered livebirths in Santa Clara County, CA, in 1986 and 1987. We interviewed women about the number of hours they spent doing heavy housework and caring for young children. We also interviewed women employed during their pregnancies (71% in each group) about their work schedule; the number of hours they worked, stood, commuted, and stooped or bent; and the number of times per day they lifted weights of >15 pounds. Standing >8 hours per day at work was the only variable associated with increased risk [adjusted odds ratio (OR) = 1.6; 95% confidence limits (CL) = 1.1, 2.3]. This association was present only for women with a history of spontaneous abortion (adjusted OR = 2.8; 95% CL = 1.4, 5.9). Among women with this history, the OR for a second trimester abortion was 4.9 (95% CL = 1.9, 12.2). Cleaning house for >7 hours per week or caring for young children for >50 hours per week was associated with decreased risk (adjusted OR = 0.6, 95% CL = 0.5, 0.9; adjusted OR = 0.8, 95% CL = 0.6, 1.0, respectively). Again, these associations were specific to women with a history of spontaneous abortion (adjusted OR = 0.4, 95% CL = 0.2, 0.7; adjusted OR = 0.5, 95% CL = 0.3, 0.8). These results indicate that the specific type of physical exertion, the amount of exertion, and the context of the exertion may be important.

Meeting Report: Consensus Statement—Parkinson’s Disease and the Environment: Collaborative on Health and the Environment and Parkinson’s Action Network (CHE PAN) Conference 26–28 June 2007.

Background Parkinson’s disease (PD) is the second most common neurodegenerative disorder. People with PD, their families, scientists, health care providers, and the general public are increasingly interested in identifying environmental contributors to PD risk. Methods In June 2007, a multidisciplinary group of experts gathered in Sunnyvale, California, USA, to assess what is known about the contribution of environmental factors to PD. Results We describe the conclusions around which they came to consensus with respect to environmental contributors to PD risk. We conclude with a brief summary of research needs. Conclusions PD is a complex disorder, and multiple different pathogenic pathways and mechanisms can ultimately lead to PD. Within the individual there are many determinants of PD risk, and within populations, the causes of PD are heterogeneous. Although rare recognized genetic mutations are sufficient to cause PD, these account for < 10% of PD in the U.S. population, and incomplete penetrance suggests that environmental factors may be involved. Indeed, interplay among environmental factors and genetic makeup likely influences the risk of developing PD. There is a need for further understanding of how risk factors interact, and studying PD is likely to increase understanding of other neurodegenerative disorders.

Infants of Mexican immigrants. Health status of an emerging population.

Previous studies suggest that infants of Mexican immigrants have favorable birth outcomes despite their high socioeconomic risks. These favorable outcomes have been associated with a protective sociocultural orientation among immigrants. A sample of 708 infants of Mexican origin was assessed to determine whether such health advantages at birth are sustained at 8 to 16 months of age, or alternatively, whether their health deteriorates because of adverse socioeconomic conditions. A a cross-sectional survey was conducted in San Diego County to determine whether the child was healthy or ill (the latter indicating a history of serious infectious disease) and the factors associated with this outcome. Among infants born without serious medical problems, 74% remained healthy. For 26% of the infants, their health status was eroded by social conditions. Factors associated with illness were large households, barriers to care, and maternal characteristics including smoking, pregnancy complications, and employment. Women born in Mexico who were newcomers to the United States and spoke Spanish exclusively were more likely than non-newcomers to have ill children. In this population, one fourth of Latino infants of immigrants were at high risk for serious infectious disease despite using preventive care.

Environmental Public Health Tracking of Childhood Asthma Using California Health Interview Survey, Traffic, and Outdoor Air Pollution Data

Background Despite extensive evidence that air pollution affects childhood asthma, state-level and national-level tracking of asthma outcomes in relation to air pollution is limited. Objectives Our goals were to evaluate the feasibility of linking the 2001 California Health Interview Survey (CHIS), air monitoring, and traffic data; estimate associations between traffic density (TD) or outdoor air pollutant concentrations and childhood asthma morbidity; and evaluate the usefulness of such databases, linkages, and analyses to Environmental Public Health Tracking (EPHT). Methods We estimated TD within 500 feet of residential cross-streets of respondents and annual average pollutant concentrations based on monitoring station measurements. We used logistic regression to examine associations with reported asthma symptoms and emergency department (ED) visits/hospitalizations. Results Assignment of TD and air pollution exposures for cross-streets was successful for 82% of children with asthma in Los Angeles and San Diego, California, Counties. Children with asthma living in high ozone areas and areas with high concentrations of particulate matter < 10 μm in aerodynamic diameter experienced symptoms more frequently, and those living close to heavy traffic reported more ED visits/hospitalizations. The advantages of the CHIS for asthma EPHT include a large and representative sample, biennial data collection, and ascertainment of important socio-demographic and residential address information. Disadvantages are its cross-sectional design, reliance on parental reports of diagnoses and symptoms, and lack of information on some potential confounders. Conclusions Despite limitations, the CHIS provides a useful framework for examining air pollution and childhood asthma morbidity in support of EPHT, especially because later surveys address some noted gaps. We plan to employ CHIS 2003 and 2005 data and novel exposure assessment methods to re-examine the questions raised here.