Archive for the ‘Environmental Health Perspectives’ Category

Near-Roadway Pollution and Childhood Asthma: Implications for Developing “Win-Win” Compact Urban Development and Clean Vehicle Strategies

September 25, 2012 Comments off

Near-Roadway Pollution and Childhood Asthma: Implications for Developing “Win-Win” Compact Urban Development and Clean Vehicle Strategies

Source: Environmental Health Perspectives

Background: The emerging consensus that exposure to near-roadway traffic-related pollution causes asthma has implications for compact urban development policies designed to reduce driving and greenhouse gases.

Objectives: We estimated the current burden of childhood asthma-related disease attributable to near-roadway and regional air pollution in Los Angeles County (LAC) and the potential health impact of regional pollution reduction associated with changes in population along major traffic corridors.

Methods: The burden of asthma attributable to the dual effects of near-roadway and regional air pollution was estimated, using nitrogen dioxide and ozone as markers of urban combustion-related and secondary oxidant pollution, respectively. We also estimated the impact of alternative scenarios that assumed a 20% reduction in regional pollution in combination with a 3.6% reduction or 3.6% increase in the proportion of the total population living near major roads, a proxy for near-roadway exposure.

Results: We estimated that 27,100 cases of childhood asthma (8% of total) in LAC were at

least partly attributable to pollution associated with residential location within 75m of a major

road. As a result, a substantial proportion of asthma-related morbidity is a consequence of nearroadway

pollution, even if symptoms are triggered by other factors. Benefits resulting from a

20% regional pollution reduction varied markedly depending on the associated change in nearroadway


Conclusions: Our findings suggest that there are large and previously unappreciated public health consequences of air pollution in LAC and probably in other metropolitan areas with dense traffic corridors. To maximize health benefits, compact urban development strategies should be coupled with policies to reduce near-roadway pollution exposure.

Environmental Inequality in Exposures to Airborne Particulate Matter Components in the United States

August 22, 2012 Comments off

Environmental Inequality in Exposures to Airborne Particulate Matter Components in the United States
Source: Environmental Health Perspective

Growing evidence indicates that toxicity of fine particles (PM2.5) differs by chemical component. Exposure to components may differ by population.

We investigated whether exposures to PM2.5 components differ by race/ethnicity, age, and socio-economic status (SES).

Long-term exposures (2000-2006) were estimated for 215 US census tracts for PM2.5 and 14 PM2.5 components. Population-weighted exposures were combined to generate overall estimated exposures by race/ethnicity, education, poverty status, employment, age, and earnings. Population characteristics for tracts with and without PM2.5 component monitors were compared.

Larger disparities in estimated exposures were observed for components than for PM2.5 total mass. For race/ethnicity, whites generally had the lowest exposures. Non-Hispanic blacks had higher exposures than whites for 13 of the 14 components. Hispanics generally had the highest exposures (e.g., 152% higher than whites for chlorine, 94% higher for aluminum). Young persons (0-19yrs) had levels as high as or higher than other ages for all exposures except sulfate. Persons with lower SES had higher estimated exposures, with some exceptions. For example, a 10% increase in the proportion unemployed was associated with a 20.0% increase in vanadium and an 18.3% increase in elemental carbon. Census tracts with monitors had more non-Hispanic blacks, lower education and earnings, and higher unemployment and poverty than tracts without monitors.

Exposures to PM2.5 components differed by race/ethnicity, age, and SES. If some components are more toxic than others, certain populations are likely to suffer higher health burdens. Demographics differed between populations covered and not covered by monitors.

Health Benefits From Large Scale Ozone Reduction in the United States

July 26, 2012 Comments off

Health Benefits From Large Scale Ozone Reduction in the United States

Source: Environmental Health Perspectives


Exposure to ozone has been associated with adverse health effects, including premature mortality, cardiopulmonary and respiratory morbidity. In 2008, the U.S. Environmental Protection Agency (EPA) lowered the primary (health-based) National Ambient Air Quality Standard (NAAQS) for ozone to 75ppb, expressed as the fourth-highest daily maximum 8-hr average over a 24-hr period. Based on recent monitoring data, U.S. ozone levels still exceed this standard in numerous locations resulting in avoidable adverse health consequences.


To quantify the potential human health benefits from achieving the current primary NAAQS standard of 75ppb and two alternative standard levels, 70 and 60ppb, representing the range recommended by the EPA Clean Air Scientific Advisory Committee (CASAC).


We apply health impact assessment methodology to estimate numbers of deaths and other adverse health outcomes that would have been avoided during 2005, 2006 and 2007 if the current NAAQS ozone standards (or lower standards) had been met. Estimated reductions in ozone concentrations were interpolated according to geographic area and year, and concentration-response functions were obtained or derived from the epidemiological literature.


We estimated that annual numbers of avoided ozone-related premature deaths would have ranged from 1,410-2,480 at 75ppb to 2,450-4,130 at 70ppb and 5,210-7,990 at 60ppb. Acute respiratory symptoms would have been reduced by 3 million cases and school-loss days by one million cases annually if the current 75ppb standard had been attained. Substantially greater health benefits would have resulted if the CASAC recommended range of standards (70 to 60ppb) had been met.


Attaining a more stringent primary ozone standard would significantly reduce ozone-related premature mortality and morbidity.

A Sensitive Approach to Studying ASDs: Teasing Out Relationships between Autism and Maternal Smoking

July 8, 2012 Comments off

A Sensitive Approach to Studying ASDs: Teasing Out Relationships between Autism and Maternal Smoking
Source: Environmental Health Perspectives

Both genetic and environmental factors have been implicated in autism spectrum disorders (ASDs), which affect an estimated 1 in 88 children. One such environmental factor, prenatal exposure to tobacco smoke via maternal smoking, has been associated with ASDs in some studies but not others. A new study reports evidence of a positive association between maternal smoking during pregnancy and higher-functioning ASD subtypes [EHP 120(7):1042–1048; Kalkbrenner et al.].

The authors collected information on maternal smoking and other factors from the birth certificates for 633,989 children born in 1992, 1994, 1996, and 1998 in 11 U.S. states. They linked these data with surveillance data from the U.S. Centers for Disease Control and Prevention’s Autism and Developmental Disabilities Monitoring network and identified 3,315 of the children who were subsequently diagnosed with an ASD by age 8 years.

About 13% of all the mothers smoked during pregnancy, compared with about 11% of mothers with children diagnosed with an ASD. Maternal smoking has been associated with both lower education and reduced access to health care, factors that might increase the likelihood that ASDs go undiagnosed among children of women who smoked during pregnancy. When the authors corrected for this potential bias using outcome misclassification sensitivity analyses, a weak positive association emerged between maternal smoking and cases classified as “ASD not otherwise specified,” which were assumed to be higher-functioning ASDs such as Asperger’s disorder. The association was not found for lower-functioning (that is, more severe) ASDs.

The authors write that their findings concerning ASD subgroups should be interpreted with caution because the accuracy of subgroup classification may have varied depending upon mothers’ access to evaluation services, and because it was not bas ed on direct clinical observation. They also note that positive associations may reflect the presence in higher-functioning subgroups of children with co-occurring disorders (such as attention deficit/hyperactivity disorder) that can be affected by nicotine exposure.

Strengths of the study include the large sample size, the population-based design with standardized identification of ASD cases, and the use of sensitivity analyses to evaluate potential sources of bias. The authors conclude that the observed association between maternal smoking during pregnancy and higher-functioning ASDs warrants further research.

Lung Cancer and Elemental Carbon Exposure in Trucking Industry Workers

June 4, 2012 Comments off

Lung Cancer and Elemental Carbon Exposure in Trucking Industry Workers
Source: Environmental Health Perspectives

Background: Diesel exhaust has been considered to be a probable lung carcinogen based on studies of occupationally exposed workers. Efforts to define lung cancer risk in these studies have been limited in part by lack of quantitative exposure estimates.

Objectives: We conducted a retrospective cohort study to assess lung cancer mortality risk in US trucking industry workers. Elemental carbon (EC) was used as a surrogate of exposure to engine exhaust from diesel vehicles, traffic, and loading dock operations.

Methods: Work records were available for 31,135 male workers employed in the unionized US trucking industry in 1985. A statistical model based on a national exposure assessment was used to estimate historical work-related exposures to EC. Lung cancer mortality was ascertained through 2000 and associations with cumulative and average EC were estimated using proportional hazards models.

Results: Duration of employment was inversely associated with lung cancer risk consistent with a healthy worker survivor effect and a cohort comprised of prevalent hires. Adjusting for employment duration, there was suggestion of a linear exposure-response relationship. For each 1000 µg/m3-months of cumulative EC, based on a 5-year exposure lag, the Hazard Ratio (HR) = 1.07 (95%CI: 0.99, 1.15) with a similar association for a 10-year exposure lag, HR=1.09 (95%CI: 0.99, 1.20). Average exposure was not associated with relative risk.

Conclusions: Lung cancer mortality in trucking industry workers increased in association with cumulative exposure to EC after adjustment for negative confounding by employment duration.

Information Quality in Regulatory Decision-making: Peer Review Versus Good Laboratory Practice

February 25, 2012 Comments off
Source:  Environmental Health Perspectives (CDC)
There is an ongoing discussion on the provenance of toxicity testing data regarding how best to ensure its validity and credibility. A central argument is whether journal peer review procedures are superior to Good Laboratory Practice (GLP) standards employed for compliance with regulatory mandates.
We examined pertinent published literature on the broader issue of how scientific data quality and validity is evaluated in peer review, GLP, and development of regulations.
Some contend that peer review is a coherent, consistent evaluative procedure providing quality control for experimental data generation, analysis, and reporting sufficient to reliably establish relative merit, whereas GLP is merely a tracking process designed to thwart investigator corruption. This view is not supported by published analyses pointing to subjectivity and variability in peer review processes. Although GLP is not designed to establish relative merit, it is an internationally-accepted quality assurance, quality control (QA/QC) method for documenting experimental conduct and data.
Neither process is completely sufficient for establishing relative scientific soundness. However, a convergence for ensuring information quality is evident both by changes to peer review processes and by regulatory guidance concerning clearer, more transparent communication of scientific information. The solution to determining relative merit lies in developing a well-documented, generally-accepted weight-of-evidence scheme to evaluate both peer reviewed and GLP information used in regulatory decision-making where both merit and specific relevance inform the process.

Full Paper (PDF)

Trending Now: Using Social Media to Predict and Track Disease Outbreaks

January 5, 2012 Comments off
Source:  Environmental Health Perspectives

It’s winter, flu season, and you’re at your computer feeling a bit woozy, with an unwanted swelling in the back of your throat and a headache coming on. If you’re like millions of other people, you might engage in a moment of Internet-enabled self-diagnosis. You pop your symptoms into a search engine, and in the blink of an eye dozens of health-related websites appear on your screen. That search supplied you with information—some useful and some not—but in today’s hyper-connected world, it also supplied a data point for those who survey disease outbreaks by monitoring how people report symptoms via social media. In fact, social media, cell phones, and other communication modes have opened up a two-way street in health research, supplying not just a portal for delivering information to the public but also a channel by which people reveal their concerns, locations, and physical movements from one place to another.

That two-way street is transforming disease surveillance and the way that health officials respond to disasters and pandemics. It’s also raising hard questions about privacy and about how data streams generated by cell-phone and social-media use might be made available for health research. “There’s a challenge here in that some of these [data] systems are tightening in terms of access,” says John Brownstein, director of the computational epidemiology group at Children’s Hospital Boston and an associate professor of pediatrics at Harvard Medical School. “But we are seeing a movement towards data philanthropy in that companies are looking for ways to release data for health research without risking privacy. And at the same time, government officials and institutions at all levels see the data’s value and potential. To me, that’s very exciting.”

Air Quality and Exercise-Related Health Benefits from Reduced Car Travel in the Midwestern United States

December 21, 2011 Comments off
Source:  Environmental Health Perspectives

Automobile exhaust contains precursors to ozone and fine particulate matter, posing health risks. Dependency on car commuting also reduces physical fitness opportunities.
To quantify benefits from reducing automobile usage for short urban and suburban trips.
We simulated census-tract level changes in hourly pollutant concentrations from the elimination of automobile round trips ≤ 8 kilometers in 11 metropolitan areas in the Upper Midwestern U.S. using the Community Multiscale Air Quality (CMAQ) Model. Next, we estimated annual changes in health outcomes and monetary costs expected from pollution changes using EPA’s Benefits Mapping Analysis Program (BenMAP). In addition, we used WHO’s Health Economic Assessment Tool (HEAT) to calculate benefits of increased physical activity if 50% of short trips were made by bicycle.
We estimate that annual average urban PM2.5 would decline by 0.1 µg/m3 and that summer O3 would increase slightly in cities but decline regionally, resulting in net health benefits of $3.5 billion/year (95% CI: $0.4–$9.8 billion), with 25% of PM2.5 and most O3 benefits to populations outside metropolitan areas. Across the study region of approximately 31.3 million people and 37,000 total square miles, mortality would decline by approximately 1,100 deaths/year (95% CI: 856 – 1,346) due to improved air quality and increased exercise. Making 50% of short trips by bicycle would yield savings of approximately $3.8 billion/year from avoided mortality and reduced health care costs (95% CI: $2.7 – $5.0 billion). We estimate that the combined benefits of improved air quality and physical fitness would exceed $7 billion/year.
Our findings suggest that significant health and economic benefits are possible if bicycling replaces short car trips. Less auto dependence in urban areas would also improve health in downwind rural settings.

Full Paper (PDF)

Associations Between the Quality of the Residential Built Environment and Pregnancy Outcomes Among Women in North Carolina

December 11, 2011 Comments off

Associations Between the Quality of the Residential Built Environment and Pregnancy Outcomes Among Women in North Carolina
Source: Environmental Health Perspectives

Background: The built environment, a key component of environmental health, may be an important contributor to health disparities, particularly for reproductive health outcomes.

Objective: The study investigates the relationship between seven indices of the residential built environment quality and adverse reproductive outcomes for Durham, North Carolina (NC).

Methods: We surveyed approximately 17,000 residential tax parcels in Central Durham assessing over 50 individual variables on each. These directly-observed data were combined with tax assessor, public safety, and US Census data to construct seven indices (housing damage, property disorder, security measures, tenure (owner or renter-occupied), vacancy, crime count and nuisance count) representing important domains of the residential built environment. Fixed slope random intercept multilevel models estimated the association between the residential built environment and five adverse birth outcomes. Models were adjusted for maternal characteristics and clustered at the primary adjacency community unit, defined as the index block, plus all adjacent blocks that share any portion of a line segment (block boundary) or vertex.

Results: Five built environment indices (housing damage, property disorder, tenure status, vacancy status, and nuisances) were associated with each of our five outcomes (preterm birth (PTB), small for gestational age (SGA), low birthweight (LBW), continuous birthweight and birthweight-percent for gestational age (sex-specific birthweight distributions for infants delivered at each gestational age using National Center for Health Statistics referent births for 2000-2004)) in the unadjusted context, but some estimates were attenuated following adjustment. In models adjusted for individual-level covariates, housing damage remained statistically significantly associated with SGA, birthweight and birthweight-percent for gestational age.

Conclusion: This work suggests a real and meaningful relationship between the quality of the residential built environment and birth outcomes, which we argue are a good measure of general community health.

+ Full Paper (PDF)

Complex Factors in the Etiology of Gulf War Illness: Wartime Exposures and Risk Factors in Veteran Subgroups

September 21, 2011 Comments off

Complex Factors in the Etiology of Gulf War Illness: Wartime Exposures and Risk Factors in Veteran Subgroups
Source: Environmental Health Perspectives

Background. At least one fourth of U.S. veterans who served in the 1990-1991 Gulf War are affected by the chronic symptomatic illness known as Gulf War illness (GWI). Clear determination of the causes of GWI has been hindered by many factors, including limitations in how epidemiologic studies have assessed the impact of the complex deployment environment on veterans’ health.

Objective. To address GWI etiologic questions by evaluating the association of symptomatic illness with characteristics of veterans’ deployment.

Methods. Veteran-reported wartime experiences were compared in a population-based sample of 304 Gulf War veterans: 144 cases who met pre-established criteria for GWI and 160 controls. Analyses considered veteran subgroups and confounding among deployment variables.

Results. Deployment experiences and the prevalence of GWI differed significantly by veterans’ location in theater. Among personnel who were in Iraq or Kuwait, where all battles took place, GWI was most strongly associated with using pyridostigmine bromide pills (OR=3.5, CI=1.7-7.4) and being within one mile of an exploding SCUD missile (OR=3.1, CI=1.5-6.1). For veterans who remained in support areas, GWI was significantly associated only with personal pesticide use, with increased prevalence (OR=12.7, CI=2.6-61.5) in the relatively small subgroup who wore pesticide-treated uniforms, nearly all of whom also used skin pesticides. Combat service was not significantly associated with GWI.

Conclusions. Findings support a role for a limited number of wartime exposures in the etiology of GWI, which differed in importance with the deployment milieu in which veterans served.

+ Full Paper (PDF)

See: Causes of Gulf War Illness Are Complex and Vary by Deployment Area, Study Finds (Science Daily)

I-131 Dose-Response for Incident Thyroid Cancers in Ukraine Related to the Chornobyl Accident

April 29, 2011 Comments off

I-131 Dose-Response for Incident Thyroid Cancers in Ukraine Related to the Chornobyl Accident
Source: Environmental Health Perspectives

Background: Current knowledge about Chornobyl-related thyroid cancer risks comes from ecological studies based on grouped doses, case-control studies and studies of prevalent cancers.

Objective: To address this limitation, we evaluated the dose-response for incident thyroid cancers using measurement-based individual iodine-131 (I-131) thyroid dose estimates in a prospective analytic cohort study.

Methods: The cohort consists of individuals < 18 years on April 26, 1986, who resided in three contaminated oblasts (states) of Ukraine and underwent up to four thyroid screening examinations between 1998 and 2007 (N = 12,514). I-131 thyroid doses were estimated based on individual radioactivity measurements taken within two months after the accident, environmental transport models and interview data. Excess radiation risks were estimated using Poisson regression models.

Results: There were 65 incident thyroid cancers diagnosed during the 2nd-4th screenings and 73,004 person-years of observation. The dose-response was consistent with linearity on relative and absolute scales, although the excess relative risk model (ERR) described data better than the excess absolute risk (EAR) model. The ERR per Gy was 1.91 (95% CI: 0.43-6.34) and EAR per 104 PY per Gy was 2.21 (95% CI: 0.04 – 5.78). The ERR per Gy varied significantly by oblast of residence, but not by time since exposure, use of iodine prophylaxis, iodine status, sex, age, or tumor size.

Conclusions: I-131-related thyroid cancer risks persisted for two decades following exposure with no evidence of decrease during the observation period. The radiation risks, while smaller, are compatible with those of retrospective and ecological post-Chornobyl studies.

+ Full Paper (PDF)


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