Comments on: Chari, R.; Burke, T.A.; White, R.H.; Fox, M.A. Integrating Susceptibility into Environmental Policy: An Analysis of the National Ambient Air Quality Standard for Lead. Int. J. Environ. Res. Public Health 2012, 9, 1077-1096

In their recent article [1], Chari et al. call attention to the important subject of setting National Ambient Air Quality Standards (NAAQS) to provide requisite protection for public health, including the health of sensitive groups, as specified under the Clean Air Act (73 FR 66965) [2]. The authors focus on consideration of susceptibility to inform policy choices, using lead (Pb)-related neurocognitive effects and children from low socioeconomic status (SES) families in the context of alternative Pb standard levels. Our comments focus on the authors’ analysis of the scientific evidence and not on policy. We agree with the authors that the health effects evidence for Pb indicates a role (or roles) for SES-related factors in influencing childhood Pb exposure and associated health effects. We disagree, however, with the authors’ interpretation of the literature on SES influence on the shape of the concentration-response (C-R) relationship between children’s blood Pb and IQ (e.g., steepness of the slope). We further address aspects of the scientific evidence that are important to the consideration of sensitive populations in the context of the Pb NAAQS, and how the U.S. Environmental Protection Agency (EPA) considered this evidence in setting the Pb NAAQS in 2008

A Comparison of Risk Estimates for the Effect of Short-Term Exposure to PM, NO2 and CO on Cardiovascular Hospitalizations and Emergency Department Visits: Effect Size Modeling of Study Findings

Although particulate matter (PM), nitrogen dioxide (NO2) and carbon monoxide (CO) typically exist as part of a complex air pollution mixture, the evidence linking these pollutants to health effects is evaluated separately in the scientific and policy reviews of the National Ambient Air Quality Standards (NAAQS). The objective of this analysis was to use meta-regression methods to model effect estimates for several individual yet correlated NAAQS pollutants in an effort to identify factors that explain differences in the effect sizes across studies and across pollutants. We expected that our consideration of the evidence for several correlated pollutants in parallel could lead to insights regarding exposure to the pollutant mixture. We focused on studies of hospital admissions for congestive heart failure (CHF) and ischemic heart disease (IHD), which have played an important role in the evaluation of the scientific evidence communicated in the PM, NO2, and CO Integrated Science Assessments (ISAs). Of the studies evaluated, 11 CHF studies and 21 IHD studies met our inclusion requirements. The size of the risk estimates was explained by factors related to the pollution mixture, study methods, and monitoring network characteristics. Our findings suggest that additional analyses focusing on understanding differences in effect sizes across geographic areas with different pollution mixtures and monitor network designs may improve our understanding of the independent and combined effects of correlated pollutants

Lead exposure and antisocial behavior: A systematic review protocol.

BACKGROUND: Lead exposure remains highly prevalent worldwide despite decades of research highlighting its link to numerous adverse health outcomes. In addition to well-documented effects on cognition, there is growing evidence of an association with antisocial behavior, including aggression, conduct problems, and crime. An updated systematic review on this topic, incorporating study evaluation and a developmental perspective on the outcome, can advance the state of the science on lead and inform global policy interventions to reduce exposure. OBJECTIVES: We aim to evaluate the link between lead exposure and antisocial behavior. This association will be investigated via a systematic review of human epidemiological and experimental nonhuman mammalian studies. METHODS: The systematic review protocol presented in this publication is informed by recommendations for the conduct of systematic reviews in toxicology and environmental health research (COSTER) and follows the study evaluation approach put forth by the U.S. EPA Integrated Risk Information System (IRIS) program. DATA SOURCES: We will search the following electronic databases for relevant literature: PubMed, BIOSIS and Web of Science. Search results will be stored in EPA's Health and Environmental Research Online (HERO) database. STUDY ELIGIBILITY AND CRITERIA: Eligible human epidemiological studies will include those evaluating any population exposed to lead at any lifestage via ingestion or inhalation exposure and considering an outcome of antisocial behavior based on any of the following criteria: psychiatric diagnoses (e.g., oppositional defiant disorder (ODD), conduct disorder (CD), disruptive behavior disorders (DBD)); violation of social norms (e.g., delinquency, criminality); and aggression. Eligible experimental animal studies will include those evaluating nonhuman mammalian studies exposed to lead via ingestion, inhalation, or injection exposure during any lifestage. The following outcomes will be considered relevant: aggression; antisocial behavior; and altered fear, anxiety, and stress response. STUDY APPRAISAL AND SYNTHESIS METHODS: Screening will be conducted with assistance from an artificial intelligence application. Two independent reviewers for each data stream (human, animal) will screen studies with highest predicted relevance against pre-specified inclusion criteria at the title/abstract and full-text level. Study evaluation will be conducted using methods adapted from the U.S. EPA IRIS program. After data extraction, we will conduct a narrative review and quantitative meta-analysis on the human epidemiological studies as well as a narrative review of the experimental animal studies. We will evaluate the strength of each evidence stream separately and then will develop a summary evidence integration statement based on inference across evidence streams

Associations of Ozone and PM2.5 Concentrations With Parkinson's Disease Among Participants in the Agricultural Health Study

ObjectiveThis study describes associations of ozone and fine particulate matter with Parkinson's disease observed among farmers in North Carolina and Iowa.MethodsWe used logistic regression to determine the associations of these pollutants with self-reported, doctor-diagnosed Parkinson's disease. Daily predicted pollutant concentrations were used to derive surrogates of long-term exposure and link them to study participants' geocoded addresses.ResultsWe observed positive associations of Parkinson's disease with ozone (odds ratio = 1.39; 95% CI: 0.98 to 1.98) and fine particulate matter (odds ratio = 1.34; 95% CI: 0.93 to 1.93) in North Carolina but not in Iowa.ConclusionsThe plausibility of an effect of ambient concentrations of these pollutants on Parkinson's disease risk is supported by experimental data demonstrating damage to dopaminergic neurons at relevant concentrations. Additional studies are needed to address uncertainties related to confounding and to examine temporal aspects of the associations we observed

Contribution of Particle-Size-Fractionated Airborne Lead to Blood Lead during the National Health and Nutrition Examination Survey, 1999–2008

The objective of this work is to examine associations between blood lead (PbB) and air lead (PbA) in particulate matter measured at different size cuts by use of PbB concentrations from the National Health and Nutrition Examination Survey and PbA concentrations from the U.S. Environmental Protection Agency for 1999–2008. Three size fractions of particle-bound PbA (TSP, PM₁₀, and PM_2.5) data with different averaging times (current and past 90-day average) were utilized. A multilevel linear mixed effect model was used to characterize the PbB–PbA relationship. At 0.15 μg/m³, a unit decrease in PbA in PM₁₀ was significantly associated with a decrease in PbB of 0.3–2.2 μg/dL across age groups and averaging times. For PbA in PM_2.5 and TSP, slopes were generally positive but not significant. PbB levels were more sensitive to the change in PbA concentrations for children (1–5 and 6–11 years) and older adults (≥60 years) than teenagers (12–19 years) and adults (20–59 years). For the years following the phase-out of Pb in gasoline and a resulting upward shift in the PbA particle size distribution, PbA in PM₁₀ was a statistically significant predictor of PbB. The results also suggest that age could affect the PbB–PbA association, with children having higher sensitivity than adults