Kimberly A. Gray

The outdoor air pollution and brain health workshop

Accumulating evidence suggests that outdoor air pollution may have a significant impact on central nervous system (CNS) health and disease. To address this issue, the National Institute of Environmental Health Sciences/National Institute of Health convened a panel of research scientists that was assigned the task of identifying research gaps and priority goals essential for advancing this growing field and addressing an emerging human health concern. Here, we review recent findings that have established the effects of inhaled air pollutants in the brain, explore the potential mechanisms driving these phenomena, and discuss the recommended research priorities/approaches that were identified by the panel.

The Faroes statement: Human Health effects of developmental exposure to chemicals in our environment

The periods of embryonic, foetal and infant developmentare remarkably susceptible to environmental hazards. Toxicexposures to chemical pollutants during these windows ofincreased susceptibility can cause disease and disability ininfants, children and across the entire span of human life.Among the effects of toxic exposures recognized in the pasthave been spontaneous abortion, congenital malformations,lowered birthweight and other adverse effects. These outcomesmay be readily apparent. However, even subtle changes causedby chemical exposures during early development may leadto important functional deficits and increased risks ofdisease later in life. The timing of exposure during early lifehas therefore become a crucial factor to be considered intoxicological assessments.During 20–24 May 2007, researchers in the fields of environmentalhealth, environmental chemistry, developmentalbiology, toxicology, epidemiology, nutrition and paediatricsgathered at the International Conference on Fetal Programmingand Developmental Toxicity, in Torshavn, FaroeIslands. The conference goal was to highlight new insightsinto the effects of prenatal and early postnatal exposure tochemical agents, and their sustained effects on the individualthroughout the lifespan. The conference brought togetherresearchers to focus on human data and the translationof laboratory results to elucidate the environmental risks tohuman health.

Developmental Origins of Health and Disease: Integrating Environmental Influences

There are now robust data supporting the Developmental Origins of Health and Disease (DOHaD) paradigm. This includes human and animal data focusing on nutrition or environmental chemicals during development. However, the term DOHaD has not been generally accepted as the official term to be used when one is concerned with understanding the pathophysiological basis for how environmental influences acting during early development influence the risk of later noncommunicable diseases. Similarly, there is no global research or public health program built around the DOHaD paradigm that encompasses all aspects of environment. To better inform the global health efforts aimed at addressing the growing epidemic of chronic noncommunicable diseases of environmental origin, we propose a two-pronged approach: first, to make it clear that the current concept of DOHaD comprehensively includes a range of environmental factors and their relevance to disease occurrence not just throughout the life span but potentially across several generations; and second, to initiate the discussion of how adoption of DOHaD can promote a more realistic, accurate, and integrative approach to understanding environmental disruption of developmental programming and better inform clinical and policy interventions.

Developmental Origins of Health and Disease

There are now robust data supporting the Developmental Origins of Health and Disease (DOHaD) paradigm. This includes human and animal data focusing on nutrition or environmental chemicals during development. However, the term DOHaD has not been generally accepted as the official term to be used when one is concerned with understanding the pathophysiological basis for how environmental influences acting during early development influence the risk of later noncommunicable diseases. Similarly, there is no global research or public health program built around the DOHaD paradigm that encompasses all aspects of environment. To better inform the global health efforts aimed at addressing the growing epidemic of chronic noncommunicable diseases of environmental origin, we propose a two-pronged approach: first, to make it clear that the current concept of DOHaD comprehensively includes a range of environmental factors and their relevance to disease occurrence not just throughout the life span but potentially across several generations; and second, to initiate the discussion of how adoption of DOHaD can promote a more realistic, accurate, and integrative approach to understanding environmental disruption of developmental programming and better inform clinical and policy interventions.

Children's health in Latin America: the influence of environmental exposures

Background Chronic diseases are increasing among children in Latin America. Objective and Methods To examine environmental risk factors for chronic disease in Latin American children and to develop a strategic initiative for control of these exposures, the World Health Organization (WHO) including the Pan American Health Organization (PAHO), the Collegium Ramazzini, and Latin American scientists reviewed regional and relevant global data. Results Industrial development and urbanization are proceeding rapidly in Latin America, and environmental pollution has become widespread. Environmental threats to children’s health include traditional hazards such as indoor air pollution and drinking-water contamination; the newer hazards of urban air pollution; toxic chemicals such as lead, asbestos, mercury, arsenic, and pesticides; hazardous and electronic waste; and climate change. The mix of traditional and modern hazards varies greatly across and within countries reflecting industrialization, urbanization, and socioeconomic forces. Conclusions To control environmental threats to children’s health in Latin America, WHO, including PAHO, will focus on the most highly prevalent and serious hazards—indoor and outdoor air pollution, water pollution, and toxic chemicals. Strategies for controlling these hazards include developing tracking data on regional trends in children’s environmental health (CEH), building a network of Collaborating Centres, promoting biomedical research in CEH, building regional capacity, supporting development of evidence-based prevention policies, studying the economic costs of chronic diseases in children, and developing platforms for dialogue with relevant stakeholders. Citation Laborde A, Tomasina F, Bianchi F, Bruné MN, Buka I, Comba P, Corra L, Cori L, Duffert CM, Harari R, Iavarone I, McDiarmid MA, Gray KA, Sly PD, Soares A, Suk WA, Landrigan PJ. 2015. Children’s health in Latin America: the influence of environmental exposures. Environ Health Perspect 123:201–209; http://dx.doi.org/10.1289/ehp.1408292

Research on the Premotor Symptoms of Parkinson’s Disease: Clinical and Etiological Implications

Background: The etiology and natural history of Parkinson’s disease (PD) are not well understood. Some non-motor symptoms such as hyposmia, rapid eye movement sleep behavior disorder, and constipation may develop during the prodromal stage of PD and precede PD diagnosis by years. Objectives: We examined the promise and pitfalls of research on premotor symptoms of PD and developed priorities and strategies to understand their clinical and etiological implications. Methods: This review was based on a workshop, Parkinson’s Disease Premotor Symptom Symposium, held 7–8 June 2012 at the National Institute of Environmental Health Sciences in Research Triangle Park, North Carolina. Discussion: Research on premotor symptoms of PD may offer an excellent opportunity to characterize high-risk populations and to better understand PD etiology. Such research may lead to evaluation of novel etiological hypotheses such as the possibility that environmental toxicants or viruses may initiate PD pathogenesis in the gastrointestinal tract or olfactory bulb. At present, our understanding of premotor symptoms of PD is in its infancy and faces many obstacles. These symptoms are often not specific to PD and have low positive predictive value for early PD diagnosis. Further, the pathological bases and biological mechanisms of these premotor symptoms and their relevance to PD pathogenesis are poorly understood. Conclusion: This is an emerging research area with important data gaps to be filled. Future research is needed to understand the prevalence of multiple premotor symptoms and their etiological relevance to PD. Animal experiments and mechanistic studies will further understanding of the biology of these premotor symptoms and test novel etiological hypothesis. Citation: Chen H, Burton EA, Ross GW, Huang X, Savica R, Abbott RD, Ascherio A, Caviness JN, Gao X, Gray KA, Hong JS, Kamel F, Jennings D, Kirshner A, Lawler C, Liu R, Miller GW, Nussbaum R, Peddada SD, Comstock Rick A, Ritz B, Siderowf AD, Tanner CM, Tröster AI, Zhang J. 2013. Research on the premotor symptoms of Parkinson’s Disease: clinical and etiological implications. Environ Health Perspect 121:1245–1252; http://dx.doi.org/10.1289/ehp.1306967

Elucidating the Links Between Endocrine Disruptors and Neurodevelopment

Recent data indicate that approximately 12% of children in the United States are affected by neurodevelopmental disorders, including attention deficit hyperactivity disorder, learning disorders, intellectual disabilities, and autism spectrum disorders. Accumulating evidence indicates a multifactorial etiology for these disorders, with social, physical, genetic susceptibility, nutritional factors, and chemical toxicants acting together to influence risk. Exposure to endocrine-disrupting chemicals during the early stages of life can disrupt normal patterns of development and thus alter brain function and disease susceptibility later in life. This article highlights research efforts and pinpoints approaches that could shed light on the possible associations between environmental chemicals that act on the endocrine system and compromised neurodevelopmental outcomes.

Review of developmental origins of health and disease publications in environmental epidemiology

The Developmental Origins of Health and Disease (DOHaD) scientific field investigates the influence of early life environmental stressors on later life health outcomes. Environmental chemical exposures are a particular focus area within this field. Although the DOHaD hypothesis originated in the 1990s, the data evaluating this hypothesis in environmental epidemiology has not been comprehensively summarized. We conducted a scoping literature review to describe the human evidence for the DOHaD hypothesis and to identify, 1) where there may be reasonable data to draw conclusions, and 2) areas warranting further research. Using PubMed and Web of Science we identified 425 publications through 2014 that met our criteria for evaluating the DOHaD hypothesis in environmental epidemiology. These publications covered 60 different chemicals. The majority of publications focused on neurological/cognitive outcomes, followed by cancer, and respiratory outcomes. We note areas ready for more detailed review, those requiring more data and ideas for future directions.

Strength in numbers: three separate studies link in utero organophosphate pesticide exposure and cognitive development.

Children entering classrooms for the first time this fall can be seen carrying backpacks filled with school supplies, yet each new student brings something less obvious but more important—a legacy of their earlier experiences and environment. Three studies published in this issue of Environmental Health Perspectives (Bouchard et al. 2011; Engel et al. 2011; Rauh et al. 2011) deliver compelling new data linking one aspect of a child’s history—in utero exposure to organophosphates (OP), a commonly used class of pesticides—and early cognitive development. Working memory, perceptual reasoning, and IQ were among the measures of intellectual development associated with prenatal OP exposure. Bouchard et al. (2011) found that children in the category corresponding to the highest 20% of maternal urinary levels of OP metabolites during pregnancy showed a 7-point decrease in full scale IQ compared with children of mothers in the lowest 20%, an association of magnitude similar to that observed with an increase in blood lead concentrations from 1 to 10 µg/dL (Canfield et al. 2003). The strength of evidence arising from these studies reflects, in part, their rigorous study design. Each used a longitudinal birth cohort, a design well suited to detect the evolution of exposure effects over time. Accordingly, the latest findings build on previous data from these birth cohorts showing relationships between prenatal OP pesticide exposure levels and developmental end points in the first 3 years of life (e.g., Engel et al. 2007; Eskenazi et al. 2004; Rauh et al. 2006). Decrements in full-scale IQ, working memory, and perceptual reasoning showed the most consistent associations with prenatal exposure biomarkers across studies. Comparability of these results, despite differences in populations and exposure metrics, underscores the robustness of this latest group of findings. Two of the birth cohorts represent multiethnic inner city populations in New York City, while the third cohort comprises low-income families living in California’s Salinas Valley, an agricultural area. Rauh et al. (2011) measured chlorpyrifos in cord blood, whereas Engel et al. (2011) and Bouchard et al. (2011) relied on measurement of nonspecific OP metabolites in maternal urine samples collected during pregnancy. A primary limitation of these three studies relates to exposure assessment. One study measured chlorpyrifos and diazinon in blood (Rauh et al. 2011), but the other studies (Bouchard et al. 2011; Engel et al. 2011) measured OP pesticide breakdown products in urine. Some of these breakdown products can also be found pre-formed in food; thus, measurements in urine do not show how much exposure was due to the parent pesticide compounds or the preformed breakdown product. Another complication is that measurement of the breakdown products reflects exposure to many different OP pesticides, some that are much more toxic than others. For many OP pesticides, however, there are no laboratory methods to measure the parent pesticides in blood or specific breakdown products in urine at levels needed for epidemiologic research. The National Institute of Environmental Health Sciences (NIEHS), through the Exposure Biology Program, is supporting efforts to improve exposure assessment for epidemiological research. The three birth cohort studies highlighted here were initiated in the first phase of the Children’s Centers for Environmental Health and Disease Prevention Research Program. This program was developed jointly by the NIEHS and the U.S. Environmental Protection Agency (EPA) in response to a 1997 Executive Order that charged agencies to prioritize the identification and assessment of environmental health risks to children and to ensure that policies, programs, activities, and standards address these risks (Clinton 1997). At present, six full centers and six developmental/formative Children’s Centers, each comprised of interdisciplinary research teams, receive support through this program. Collectively, these centers are addressing a range of established and emerging priority issues in the environmental health of children, including neurodevelopment, respiratory health, and endocrine function. An important component of these NIEHS/U.S. EPA Children’s Centers is meaningful engagement of affected communities. Although not the focus of the articles in this issue of EHP, all three research teams have community outreach and translation cores whose primary objective is to rapidly and effectively translate the center study findings at local, state, and national levels to communities and stakeholders. These efforts have taken various forms, from hosting town hall meetings, developing community advisory boards, and encouraging integrated pest management solutions in New York City to outreach efforts to reduce take home exposures among farm workers in the Salinas Valley. The present findings in young children are likely to have implications for longer-term learning and academic success. Determining the persistence of these associations, and their generalizability to other populations, requires additional study. The U.S. EPA began a phase-out of the residential use of chlorpyrifos and diazinon in 2001 and 2004, respectively, which led to a marked reduction of markers of chlorpyrifos exposure in the United States, yet exposure to children continues due to use of organophosphate pesticides on crops and residues on foods. Spurred by recent advances in mechanistic toxicology and exposure science, efforts to improve identification of neurodevelopmental toxicity of new and existing industrial compounds are under way (e.g., U.S. Senate Committee on Environment & Public Works 2009). The findings of Bouchard et al. (2011), Engel et al. (2011), and Rauh et al. (2011) should stimulate renewed efforts to develop and fully implement measures that can identify threats before widespread exposure occurs and harms pregnant women and children.

The Childrenʼs Health Exposure Analysis Resource: enabling research into the environmental influences on childrenʼs health outcomes

Purpose of review The Childrens Health Exposure Analysis Resource (CHEAR) is a new infrastructure supported by the National Institute of Environmental Health Sciences to expand the ability of childrens health researchers to include analysis of environmental exposures in their research and to incorporate the emerging concept of the exposome. Recent findings There is extensive discussion of the potential of the exposome to advance understanding of the totality of environmental influences on human health. Childrens health is a logical choice to demonstrate the exposome concept due to the extensive existing knowledge of individual environmental exposures affecting normal health and development and the short latency between exposures and observable phenotypes. Achieving this demonstration will require access to extensive analytical capabilities to measure a suite of exposures through traditional biomonitoring approaches and to cross-validate these with emerging exposomic approaches. Summary CHEAR is a full-service exposure assessment resource, linking up-front consultation with both laboratory and data analysis. Analyses of biological samples are intended to enhance studies by including targeted analysis of specific exposures and untargeted analysis of small molecules associated with phenotypic endpoints. Services provided by CHEAR are made available without cost but require a brief application and adherence to policies detailed on the CHEAR web page at https://chearprogram.org/.