Environews
FOCUS | Contaminants in Human Milk: Weighing the Risks against the Benefits of Breastfeeding
For some 200 million years, human milk has served as the perfect food for the human infant, with breastfeeding providing myriad physical and emotional benefits believed to continue long after weaning. With increasing discoveries of toxic chemicals in milk, however, questions arise as to whether the benefits of breastfeeding outweigh the potential risks posed by infant exposure to biopersistent chemicals in milk. This article p. A426) explores the evidence.
SPHERES OF INFLUENCE | Wild Child: Guiding the Young Back to Nature
As a result of profound lifestyle, societal, and technological changes in the past 30 years, including academic achievement legislation that has left some schools foregoing recess in favor of more class time, children today can go for days without having a single meaningful encounter with nature. This article (p. A436) looks at how limited contact with the natural world may affect future generations of environmental health stewards.
Commentary
POPULATION HEALTH | CBPR and Public Engagement in China's Environmental Health
Because of its remarkable economic growth and rapid agricultural-to-industrial and rural-to-urban transitions over the past 25 years, China now faces many environmental challenges that significantly affect human health and the quality of life. Ali et al. (p. 1281) highlight the success of community-based participatory research (CBPR)—a collaborative approach to research involving community members, organizational representatives, and researchers as equal participants the research process—in the United States. They suggest CBPR as a model for addressing environmental health problems in China.
Review
CHILDREN' HEALTH | Lead Exposure in U.S. Children, 2008
To evaluate whether the U.S. public health goal to eliminate pediatric elevated blood lead levels (EBLs) by 2010 can be met, Levin et al. (p. 1285) reviewed the sources of lead in the environments of U.S. children and their contributions to children's blood lead levels, source elimination and control efforts, and existing federal authorities. They determined that the 2010 goal can be met if current efforts are maintained, especially programs addressing lead paint, and additional interventions that prevent exposure continue to be developed. It will also require active collaboration across all levels of government to identify and control all potential sources of lead exposure, as well as the continuation of primary prevention activities.
Research
CARDIOVASCULAR DISEASE | Particulate Matter and Pulmonary Circulation
Because pulmonary circulation is the primary vascular target of inhaled particulate matter (PM) and because nitric oxide (NO) a major vasculoprotective agent, Courtois et al. (p. 1294) investigated the effect of various particles on the NO–cyclic guanosine monophosphate (cGMP) pathway in pulmonary arteries. They found that, in contrast to manufactured particles (including nanoparticles), urban PM impaired NO but not cGMP responsiveness in intrapulmonary arteries. The authors attribute this effect to oxidative-stress–independent inflammatory response, resulting in decreased guanylyl cyclase activation by NO. Such impairment of the NO pathway may contribute to urban-PM–induced cardiovascular dysfunction.
BUILT ENVIRONMENT | Built Environment and Physical Functioning in Hispanic Elders
In a population-based study in a low-socioeconomic-status Hispanic neighborhood, Brown et al. (p. 1300) examined whether architectural features of the built environment believed to facilitate social interactions and monitoring of behavior among residents (e.g., porches, stoops) predicted Hispanic elders' social support as well as psychological and physical functioning. Analyses suggested that elders living on blocks marked by low levels of positive front entrance features were at 2.7 times greater risk of having subsequent poor levels of physical functioning compared with elders living on blocks with a greater number of positive front entrance features.
NEURODEVELOPMENT | Parathion Developmental Neurotoxicity
Organophosphates elicit developmental neurotoxicity through multiple mechanisms other than their shared property as cholinesterase inhibitors. Accordingly, these agents may differ in their effects on specific brain circuits. Slotkin et al. (p. 1308) treated neonatal rats with parathion at doses straddling the threshold for cholinesterase inhibition and systemic effects. They found that neonatal exposure to parathion compromises indices of acetylcholine synaptic function in adolescence and adulthood. Differences between the effects of parathion compared with chlorpyrifos or diazinon and the nonmonotonic dose–effect relationships reinforce the finding that various organophosphates diverge in their effects on neurodevelopment, unrelated to their anticholinesterase actions.
METABOLISM | DE-71 Metabolites Are Weak ER-α Ligands
Polybrominated diphenyl ethers (PBDEs), which are widely found in the environment, are suspected endocrine disruptors. Mercado-Feliciano and Bigsby (p. 1315) investigated whether hydroxylated metabolites of PBDEs would interact with and alter activity of estrogen receptor-α (ER-α). The observations that DE-71 (a commercial mixture of mostly tetra- and penta-PBDEs, which has been used extensively as a flame retardant) did not displace 3H-estradiol (3H-E2) from ER-α—while the hydroxylated metabolites did—suggests that the weak estrogenic effects of DE-71 are due to metabolic activation of individual congeners. However, the behavior of DE-71 and its metabolites when co-administered with E2 suggest a secondary, undetermined mechanism from classical ER-α activation.
NEUROBEHAVIORAL DISEASE | Lead Exposure and Tactile Defensiveness
Tactile defensiveness in children is associated with difficult social relations, emotional dysregulation, and inattention, but no studies have investigated the effects of lead exposure and tactile defensiveness in children or animals, in spite of the fact that lead exposure is also associated with inattention and emotional dysregulation. Moore et al. (p. 1322) investigated whether lead exposure induces tactile defensiveness in rhesus monkeys and examined whether succimer chelation affected lead levels. Results showed that lead-exposed monkeys had higher negative responses to repeated tactile stimulation than controls, implicating lead as a cause of tactile defensiveness. The authors also found an interaction of lead exposure 
succimer chelation trials, but it is not clear that succimer chelation was beneficial with respect to tactile defensiveness.
RISK ASSESSMENT | Lung Cancer and Vehicle Exhaust
An elevated risk of lung cancer in truck drivers has been attributed to diesel exhaust exposure, but interpretation of studies specifically implicating diesel exhaust as a carcinogen has been limited because of limited exposure measurements and lack of work records relating job title to exposure-related job duties. Garshick et al. (p. 1327) established a large retrospective cohort of trucking company workers to assess the association of lung cancer mortality and measures of vehicle exhaust exposure. They found that workers who have had regular exposure to vehicle exhaust from diesel and other types of vehicles have an elevated risk of lung cancer with increasing years of work.
RESPIRATORY DISEASE | Black Carbon and Lung Function among Women
Franco Suglia et al. (p. 1333) examined the relationship between black carbon (BC), a surrogate of traffic-related particles, and lung function among women in the Maternal-Infant Smoking Study of East Boston, an urban cohort in Boston, Massachusetts. In this cohort, exposure to traffic-related BC, a component of particulate matter, independently predicted decreased lung function in urban women after adjusting for tobacco smoke, asthma diagnosis, and socioeconomic status.
BONE AND CARTILAGE | Urinary Cadmium and Osteoporosis in U.S. Women
Urinary cadmium (U-Cd) has been associated with decreased peripheral bone mineral density (BMD) and osteoporosis. Gallagher et al. (p. 1338) investigated the statistical association between U-Cd, at levels ≤ 1 µg/g creatinine, and osteoporosis, as indicated by hip BMD and self-report, in a population-based sample of U.S. women ≥ 50 years of age. Results suggest that U.S. women are at risk for osteoporosis at U-Cd levels below the Occupational Safety and Health Administration's 3-µg/g safety standard. Based on null findings among smokers, dietary cadmium, rather than tobacco, is the likely source of cadmium-related osteoporosis risk for the U.S. female population ≥ 50 years of age.
RISK ASSESSMENT | MOE Assessment for Dioxins using Human Data
Aylward et al. (p. 1344) examined the feasibility of relying directly on human studies of exposure and potential responses to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDFs) and dioxin-like compounds in terms of measured lipid-adjusted concentrations to assess the margin of exposure (MOE) in a quantitative, benchmark dose–based framework. Using available data sets, they characterized estimated central tendency and upper-bound general U.S. population lipid-adjusted concentrations of PCDD/PCDFs from the 1970s and early 2000s using estimates of benchmark concentrations induction of cytochrome P4501A2 activity, dental anomalies, and neonatal thyroid hormone alterations.
LIVER | Perinatal Helicobacter hepaticus Exposure and Liver Tumors
Although severe hepatitis and liver tumors occur in a high percentage of A/J male mice naturally infected with Helicobacter hepaticus, these effects have not been observed in adult mice after injection with the bacteria. To test the hypothesis that perinatal exposure to the bacteria is required for liver tumorigenesis, Diwan et al. (p. 1352) treated female mice with H. hepaticus before pregnancy and examined offspring at progressive time intervals; they also treated weanling male mice and observed them for up to 2 years. Results indicate that development of liver tumors in mice infected with H. hepaticus requires perinatal exposure. Contributing perinatal factors could include known high sensitivity of neonatal liver to tumor initiation and/or modulation of immune response to the bacterium or its toxins.
Also see Science Selections, p. A440
CARDIOVASCULAR DISEASE | Long-term Exposure to NO2 and HRV
Heart rate variability (HRV), a measure of cardiac autonomic tone, has been associated with cardiovascular morbidity and mortality; short-term studies have shown that subjects exposed to higher traffic-associated air pollutant levels have lower HRV. Felber Dietrich et al. (p. 1357) investigated the effect of long-term exposure to NO2 on HRV in the Study on Air Pollution and Lung Diseases in Adults cohort study. They recorded electrocardiograms in participants ≥ 50 years of age, used hybrid models to predict annual exposure to NO2 at the address of residence, and investigated health status and measurements of blood pressure, body height, and weight. The researchers found some evidence that long-term exposure to NO2 is associated with cardiac autonomic dysfunction in elderly women and in subjects with cardiovascular disease.
ENVIRONMENTAL JUSTICE | Air Pollution, Odor, and Industrial Swine Operations
Odors can affect health and quality of life, and industrialized animal agriculture creates odorant compounds that are components of a mixture of agents that could trigger symptoms reported by neighbors of livestock operations. Wing et al. (p. 1362) quantified swine odor episodes reported by neighbors of swine concentrated animal feeding operations and their relationships with environmental measurements. Nonsmoking volunteers living within 1.5 miles of industrial swine operations in eastern North Carolina completed twice-daily odor diaries for approximately 2 weeks, and meteorological conditions, hydrogen sulfide, and particulate matter ≤ 10 µm in aerodynamic diameter were monitored in each neighborhood. Results indicate that malodor from swine operations is commonly present in these communities and that the odors reported by neighbors are related to objective environmental measurements and interruption of activities of daily life.
Environmental Medicine
NEUROBEHAVIORAL DISEASE | The Effect of Heat Waves on Mental Health Disorders
To identify mental, behavioral, and cognitive disorders that may be triggered or exacerbated during heat waves, predisposing individuals to heat-related morbidity and mortality, Hansen et al. (p. 1369) used health outcome data from Adelaide, South Australia, to estimate the effect of heat waves on hospital admissions and mortalities attributed to these disorders. Results suggest that episodes of extreme heat pose a salient risk to the mentally ill. Improvements in the management and care of the mentally ill should be addressed to avoid an increase in psychiatric morbidity and mortality exacerbated by climate change.
Children's Health
RESPIRATORY HEALTH | Children's Health after the 9/11 WTC Disaster
Thomas et al. (p. 1383) collected data on children recruited for the World Trade Center (WTC) Health Registry (WTCHR) who were < 18 years of age on 11 September 2001 (9/11) in order to describe respiratory health findings and examine associations between disaster-related exposures and respiratory health. Asthma prevalence after 9/11 among WTCHR enrollees < 5 years of age was higher than national estimates, and new asthma diagnosis was associated with dust cloud exposure in all age groups. The authors plan to determine severity of asthma and persistence of other respiratory symptoms in follow-up surveys.
Also see Science Selections, p. A440
NEURODEVELOPMENT | Perfluorinated Chemicals and Developmental Milestones
Perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) are fluorinated organic compounds present in the general population at low concentrations. Animal studies have shown that they may affect neuromuscular development at high concentrations. Fei et al. (p. 1391) investigated the association between plasma levels of PFOS and PFOA in pregnant women and motor and mental developmental milestones of their children. They found no convincing associations between developmental milestones in early childhood and levels of PFOA or PFOS as measured in maternal plasma early in pregnancy.
Also see Science Selections, p. A441
NEUROBEHAVIORAL TOXICITY | Prenatal PAH Exposure and Neurodevelopment in China
Coal burning provides 70% of the energy for China's industry and power, but it releases large quantities of polycyclic aromatic hydrocarbons (PAHs) and other pollutants (PAHs are reproductive and developmental toxicants, mutagens, and carcinogens). Perera et al. (p. 1396) evaluated the benefit to neurobehavioral development from the closure of a coal-fired power plant in Tongliang, Chongqing, China, that was the major local source of ambient PAHs, using two identical prospective cohort studies that enrolled nonsmoking women and their newborns in 2002 (before shutdown) and 2005 (after shutdown). Findings indicate that neurobehavioral development in Tongliang children benefited by elimination of PAH exposure from the coal-burning plant, consistent with the significant reduction in PAH–DNA adducts in cord blood of children in the 2005 cohort.
Also see Science Selections, p. A441
NEUROBEHAVIORAL TOXICITY | ADHD and Blood Lead Levels
Wang et al. (p. 1401) investigated the association between attention deficit/hyperactivity disorder (ADHD) and blood lead levels (BLLs) in Chinese children, adjusting for known ADHD risk factors and potential confounding variables. They found significant difference in BLLs between ADHD cases and controls. After adjustment for other known risk factors, ADHD cases were more likely to have been exposed to lead during childhood than the non-ADHD control subjects; these results were not modified by age and sex. The authors concluded that ADHD may be an additional deleterious outcome of lead exposure during childhood, even when BLLs are < 10 µg/dL.
HUMAN TOXICOLOGY | Organochlorine Compounds and Urinary Porphyrins in Children
Hexachlorobenzene (HCB) and other organochlorines induce porphyria cutanea tarda (PCT) in animal studies; however, evidence in humans is contradictory. In neonates and adults from populations historically highly exposed to HCB, no relation with PCT or porphyrin excretion has been reported. Sunyer et al. (p. 1407) analyzed the association between urinary porphyrin excretion and exposure to HCB and other organochlorinated compounds in 4-year-old children. HCB did not induce porphyria or increase uroporphyrins. However, the increase of urinary coproporphyrins suggests an incipient toxic effect of the organochlorines.
FETAL DEVELOPMENT | Air Pollution and Oral Clefts
Air pollution influences the development of oral clefts in animals. There are few epidemiologic data on the relation of prenatal air pollution exposure and the risk of oral clefts. Hwang and Jaakkola (p. 1411) assess the relations between exposure to ambient air pollution and the risk of cleft lip with or without cleft palate (CL/P). The study provides new evidence that exposure to outdoor air O3 during the first and second month of pregnancy may increase the risk of CL/P. Similar levels of O3 are encountered globally by large numbers of pregnant women.
NEUROBEHAVIORAL TOXICITY | Prenatal PCB Exposure and IQ in 9-Year-Old Children
Although several epidemiologic studies have demonstrated relationships between prenatal exposure to polychlorinated biphenyls (PCBs) and modest cognitive impairments in infancy and early childhood, few studies have followed cohorts of exposed children long enough to examine the possible impact of prenatal PCB exposure on psychometric intelligence in later childhood. To determine whether environmental exposure to PCBs predicts lower IQ in school-age children, Stewart et al. (p. 1416) measured prenatal PCB exposure and IQ at 9 years of age in 156 subjects from Oswego, New York, and also measured > 50 potential predictors of intelligence. Results show that for each 1-ng/g (wet weight) increase in PCBs in placental tissue, Full-Scale IQ dropped by three points and Verbal IQ dropped by four points.
RESPIRATORY DISEASE | Air Pollution and Respiratory Health
Dales et al. (p. 1423) assessed the effects of living near local residential roadways based on objective indicators of ventilatory function and airway inflammation in children. They estimated ambient air pollution, resolved to the level of the child's neighborhood, using a land-use regression model for children 9–11 years of age, and summed the length of roadways found within a 200-m radius of each child's neighborhood. The authors concluded that traffic from local neighborhood roadways may cause airway inflammation as indicated by exhaled nitric oxide, which may be a more sensitive indicator of adverse air pollution effects than traditional measures of ventilatory function.
ASTHMA | Indoor Nitrogen Dioxide Levels and Asthma Symptoms
To estimate the effect of indoor nitrogen dioxide concentrations on asthma morbidity in an inner-city children while adjusting for other indoor pollutants, Hansel et al. (p. 1428) recruited 150 children (2–6 years of age) with physician-diagnosed asthma from inner-city Baltimore, Maryland. Indoor air was monitored over a 72-hr period in the children's bedrooms at baseline and at 3 and 6 months. The authors found that higher indoor NO2 concentrations were associated with increased asthma symptoms in these children. Interventions aimed at lowering NO2 concentrations in inner-city homes may reduce asthma morbidity in this vulnerable population.
ASTHMA | Traffic-Related Pollution and Childhood Asthma
Jerrett et al. (p. 1433) assessed the association between asthma onset in children and traffic-related air pollution in a sample of 217 children selected from participants in the Southern California Children's Health Study, a prospective cohort designed to investigate associations between air pollution and respiratory health in children 10–18 years of age. In this cohort, markers of traffic-related air pollution were associated with the onset of asthma. The risks observed suggest that air pollution exposure contributes to new-onset asthma.
