Environews
FOCUS | Environmental LIteracy: Knowledge for a Healthier Public
With evidence continuing to mount linking the activities of our modern life to the Earth's eroding sustainability, the need for environmental literacy among the world's population has become more important than ever before. An emerging movement seeks to promote sound environmental stewardship by increasing the understanding of how our actions impact the environment we live in, but delivering relevant, useful information to all members of the multifaceted general public can be challenging. This article (p. A494) takes a look at the growth in environmental literacy initiatives over the last few decades, and discusses the potential of particular strategies to successfully effect change.
SPHERES OF INFLUENCE | Standing on Principle: The Global Push for Environmental Justice
Increased worldwide industrialization and globalization have dispatched the conveniences of modern living throughout the world. But with those advantages for some have come disparities for those living in poorer, disadvantaged communities. In the United States, environmental advocacy has gained ground as a tool to protect the health and well-being of less-privileged neighborhoods from the burdens of environmental hazards. But environmental justice concerns are not unique to any one area of the world. This article (p. A500) looks at how advocates all over the globe are working together to combat environmental injustices.
Commentary
CHILDREN'S HEALTH | Fellowship in Environmental Pediatrics
Evidence is mounting that environmental exposures contribute to causation of disease in children. However, few pediatricians are trained to diagnose, treat, or prevent diseases of environmental origin. The Ambulatory Pediatric Association (APA) launched a new 3-year fellowship in 2001 [the world's first formal training program in pediatric environmental health (PEH)] to develop a cadre of future leaders. To objectively assess the program's success in preparing fellows for leadership careers in PEH, Landrigan et al. (p. 1383) conducted a mailed survey in 2006 with follow-up in 2007. The APA fellowship program is successfully preparing pediatricians for leadership careers in PEH.
Review
GENE REGULATION/GENE EXPRESSION | Gene by Environment Interactions and Disease
Health or disease is shaped for all individuals by interactions between their genes and their environment. Current studies are exploring how the environment changes gene expression and how this can lead to disease. Edwards and Myers (p. 1264) searched the Web of Science and references of relevant publications to understand the diversity of gene regulatory mechanisms affected by environmental exposures with disease implications. These studies indicate that disease risk is best predicted in the context of genetic and environmental factors in combination.
RISK ASSESSMENT | Comparative Air Pollution Risks in Houston
To address the problem of airborne emissions from numerous point, area, and mobile sources, along with stagnant meteorologic conditions, that contribute to frequent episodes of elevated air pollution in Houston, Texas, decision makers must set priorities among thousands of individual air pollutants as they formulate effective and efficient mitigation strategies. Using an evidence-based approach supplemented by an expert panel of academic scientists, Sexton et al. (p. 1388) compared and ranked relative health risks of 179 air pollutants in Houston. They concluded that risk-based priority setting is an important step in the development of cost-effective solutions to Houston's air pollution problem.
Review
CHILDREN'S HEALTH | Secondhand Tobacco Smoke and New Childhood Asthma
Studies have identified associations between household secondhand tobacco smoke (SHS) exposure and childhood asthma, but evidence is not consistent. To determine sources of potential bias and to uncover consistent patterns of relative risk estimates, Vork et al. (p. 1394) conducted a meta-analysis of studies published between 1970 and 2005. Their findings indicate that exposure duration may be more important in the induction of asthma than previously understood, and suggest that SHS could be a more fundamental and widespread cause of childhood asthma than indicated in some previous meta-analyses.
Research
RISK ASSESSMENT | Mesothelioma Incidence in Wives of Asbestos Workers
Family members of asbestos workers are at increased risk of malignant mesothelioma (MM). The magnitude of the risk is uncertain, and it is unclear whether risk is also increased for other cancers. Ferrante et al.(p. 1401) studied a cohort of women, each who had been married to a worker of the "Eternit" factory (Casale Monferrato, Italy), which was among the most important Italian plants producing asbestos-cement (AC) goods. Results indicate that household exposure, as experienced by these AC workers' wives, increases the risk for pleural MM but not for lung cancer.
RISK CHARACTERIZATION | DDT and Breast Cancer
Previous studies of DDT and breast cancer have assessed exposure later in life when the breast may not have been vulnerable, after most DDT had been eliminated, and after DDT had been banned. Cohn et al. (p. 1406) investigated whether DDT exposure in young women during the period of peak DDT use predicts breast cancer using blood samples obtained from young women during 1959–1967. Because exposure to p,p´-DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane] early in life may increase breast cancer risk and because many U.S. women who were heavily exposed to DDT in childhood have not yet reached 50 years of age, the public health significance of DDT exposure in early life may be great.
Also see Science Selections, p. A505
BIOMONITORS | Arsenic Exposure and Cell Adhesion Molecules
Epidemiologic studies of cardiovascular disease risk factors and appropriate biomarkers in populations exposed to a wide variety of arsenic concentrations are a public health research priority. Chen et al. (p. 1415) investigated the relationship between inorganic As exposure from drinking water and plasma levels of two markers of endothelial dysfunction and vascular inflammation (soluble intercellular adhesion molecule-1 and soluble vascular adhesion molecule-1) in an As-exposed population in Araihazar, Bangladesh. Their findings indicate an effect of chronic As exposure from drinking water on vascular inflammation that persists over time and suggest a potential mechanism underlying the association between As exposure and cardiovascular disease.
MARINE SCIENCE | Mercury and Loggerhead Sea Turtle Health
The toxic effects of mercury, a pervasive environmental pollutant, have not been studied in sea turtles in spite of their threatened status and evidence of immunosuppression in diseased populations. Day et al. (p. 1421) investigated Hg toxicity in loggerhead sea turtles by examining trends between blood Hg concentrations and various health parameters. They found a positive correlation between blood Hg concentration and hematocrit, which reflects the higher affinity of Hg species for erythrocytes than for plasma. In vitro immunosuppression occurred at methylmercury concentrations that correspond to approximately 5% of the individuals and suggests that subtle negative impacts of Hg on immune function are possible at concentrations observed in the wild.
EXPOSURE ASSESSMENT | Organobromine Compounds in Plasma of Quebec Women
Although brominated flame retardants, especially polybrominated diphenyl ethers (PBDEs), have been widely used in North America, little is known about the level of exposure in human populations. Sandanger et al. (p. 1429) measured concentrations of several organobromine compounds in plasma samples from a group of postmenopausal Canadian women and investigated factors associated with exposure. Results suggest that exposure to PBDE-47 likely occurs through direct contact with the penta-PBDE formulation; however, exposure to PBDE-153 may originate in part from the food chain.
POPULATION HEALTH | Lead, Cadmium, and Mercury in the Blood of NYC Adults
As part of the New York City (NYC) Health and Nutrition Examination Survey, 2004, McKelvey et al. (p. 1435) measured blood metal concentrations in a representative sample of 1,811 adult NYC residents to assess the extent of exposure to lead, cadmium, and mercury in the population. In NYC adults, blood Hg levels were higher than national levels, which indicates a need to educate New Yorkers about how to choose fish and seafood to maximize health benefits while minimizing potential risks from exposure to Hg. Local biomonitoring can provide valuable information about environmental exposures.
DIABETES | PCBs, Pesticides, and Diabetes
Recent research suggests that diabetes, a disease of increasing incidence, is associated with exposure to polychlorinated biphenyls (PCBs) and chlorinated pesticides. Codru et al. (p. 1442) investigated the potential association between diabetes and serum levels of PCBs, dichlorodiphenyldichloroethylene (DDE), hexachlorobenzene (HCB), and mirex in a cross-sectional study of an adult Native American (Mohawk) population. Elevated serum PCBs, DDE, and HCB were positively associated with diabetes after controlling for potential confounders; however, a negative association was observed for mirex.
NEURODEGENERATIVE DISEASE | Toxicokinetics and Toxicodynamics of Paraquat
Paraquat (PQ) has been implicated as a risk factor for the Parkinson disease phenotype in humans and mice using epidemiologic or experimental approaches; however, the toxicokinetics (TK) and toxicodynamics (TD) of PQ in the brain are not well understood. Using C57BL/6J mice, Prasad et al. (p. 1448) measured TK and TD of PQ in the brain after single or repeated doses and analyzed brain regions for PQ levels, the amount of lipid peroxidation, and the functional activity of the 20S proteasome. The data suggest that PQ may be a risk factor in humans and in rodent models of the Parkinson disease phenotype.
TOXICOGENOMICS | Cadmium Transformation and Tumor Suppressor Loss
Aberrant DNA methylation, common in carcinogenesis, appears to involve reduced expression of maintenance DNA methyltransferase (DNMT1), inducing genomic hypomethylation, whereas increased expression of de novoDNMT3a or 3b causes gene-specific hypermethylation. During cadmium-induced malignant transformation, an unusual pattern of genomic hypermethylation occurs. Benbrahim-Tallaa et al. (p. 1454) assessed gene expression and DNA methylation in control and chronic Cd-transformed prostate epithelial cells (CTPE) to provide insight into the roles of specific DNMTs in oncogenesis. Data indicate that DNMT3b overexpression can result in generalized DNA hypermethylation and gene silencing but that DNMT1 is required to maintain these effects. The pattern of genomic DNA hypermethylation, combined with up-regulation of DNMT3b, may provide biomarkers to identify Cd-induced human prostate cancers.
BIOMONITORS | Identification of Gene Markers for Formaldehyde
Formaldehyde (FA) is classified as a human carcinogen and has been linked to increased leukemia rates in some epidemiologic studies. Inhalation of relatively low concentrations of FA induces sensory irritation, but little is known about the cellular alterations that occur after FA exposure in humans. Li et al. (p. 1460) profiled global gene expression in Hs 680.Tr human tracheal fibroblasts exposed to FA and developed biomarkers for the evaluation of FA exposure. The identification of gene marker candidates in vitro using microarray analysis and the validation of these markers using human samples provide a good tool for discovering genes of potential mechanistic interest and biomarkers of exposure.
OBESITY | Leanness in Mice Exposed to Dietary Phytoestrogens
Obesity is an increasingly prevalent health problem, and natural effective therapeutic approaches are required to prevent its occurrence. Phytoestrogens, plant-derived compounds with estrogenic activities, can bind to both estrogen receptors α and β and mimic the action of estrogens on target organs. Cederroth et al. (p. 1467) examined the influence of soy-derived phytoestrogens on energy balance and metabolism in CD-1 mice. The data suggest that dietary soy could have beneficial effects on obesity, but they also emphasize the importance of monitoring the phytoestrogen content of diets as a parameter of variability in animal experiments.
EXPOSURE ASSESSMENT | Atrazine Exposure
Atrazine (ATZ) is the second most abundantly applied pesticide in the United States. Measurement of ATZ's urinary mercapturic acid metabolite have indicated that < 5% of the population has been exposed to ATZ-related chemicals. Barr et al. (p. 1474) aimed to determine if ATZ exposure was underestimated by measuring its urinary mercapturic acid metabolite and if the urinary metabole profile changed with the exposure scenario. The authors concluded that exposure to ATZ-related metabolites is underestimated when only one urinary metabolite is measured, and that several urinary metabolites (e.g., diaminochlorotriazine and desethylatrazine) should be measured to accurately classify exposure to ATZ and its environmental degradates.
Environmental Medicine
LIVER | Quizalofop-p-ethyl Hepatotoxicity
Quizalofop-p-ethyl (QpE) is an often applied, slightly toxic herbicide, but severe toxicity has not been reported in humans. Elefsiniotis et al. (p. 1479) report the case of a QpE-exposed farmer who presented with obstructive cholestasis. A complete workup disclosed no other cause of liver pathology, but liver biopsy established drug-induced hepatotoxicity. The patient was treated with ursodeoxycholic acid and prednisolone; 70 days after his exposure to the herbicide, the patient had fully recovered. The authors concluded that QpE can induce a mixed cholestatic/hepatocellular liver injury.
Children's Health
NEUROBEHAVIORAL DISEASE | Agricultural Pesticide Applications and Autism
Ambient levels of pesticides ("pesticide drift") are detectable at residences near agricultural field sites. Roberts et al. (p. 1482) evaluated the hypothesis that maternal residence near agricultural pesticide applications during defined periods of gestation could be associated with the development of autism spectrum disorders (ASD) in children. Using State of California electronic files, they identified children with ASD and matched them by maternal date of last menstrual period to live-born, normal-birth-weight, term infants as controls. Proximity to pesticide applications was determined using state pesticide regulation records and Department of Water Resources land use polygons. The findings suggest the possibility of a connection between gestational exposure to organochlorine pesticides and ASD among children, which requires further study.
Also see Science Selections, p. A504
ENDOCRINE SYSTEM | Prenatal PCB Exposure and Neonatal TSH
Prenatal exposure to polychlorinated biphenyls (PCBs) may alter neurodevelopment. Also, prenatal exposure to some PCB congeners and commercial mixtures has been shown to decrease blood levels of free and total thyroxine in
animals. Chevrier et al. (p. 1490) grouped PCB congeners on the basis of their potential to induce microsomal enzymes in animals, and examined the relationship between levels of neonatal
thyroid-stimulating hormone (TSH) and prenatal exposure to PCB congeners, grouped according to their structure and potential mechanisms of action. The results support grouping PCB congeners based on their potential mechanism of action of enzyme induction when investigating associations with thyroid hormones.
Also see Science Selections, p. A505
NEURODEVELOPMENT | DNA Adducts, ETS, Child Development, and the WTC
Polycyclic aromatic hydrocarbons (PAHs), including benzo[a]pyrene (BaP), are air pollutants released by the World Trade Center (WTC) fires and urban combustion sources. Levels of BaP–DNA adducts in maternal and umbilical cord blood obtained at delivery were reported to be elevated among subjects who had resided within 1 mile of the WTC site during the month after 11 September 2001. Perera et al. (p. 1497) assessed possible effects of prenatal exposure to WTC pollutants on child development. Their results suggest that exposure to elevated levels of PAHs in conjunction with prenatal environmental tobacco smoke (ETS) exposure may have contributed to a modest reduction in cognitive development among cohort children.
FETAL DEVELOPMENT | Arsenic Metabolism in Maternal–Newborn Pairs
In Bangladesh, tens of millions of people have been consuming waterborne arsenic for decades. However, the extent to which As is transported to the fetus during pregnancy has not been well characterized. Hall et al. (p. 1503) conducted a study of pregnant women who gave birth in Matlab, Bangladesh. Maternal and cord blood sample pairs were collected and analyzed for concentrations of total As and As metabolites and for plasma concentrations of plasma folate, cobalamin, and homocysteine. Concentrations of maternal urinary As metabolites were also measured. For 38% of the cases, As concentrations in water from household tube wells exceeded the World Health Organization guidelines. The authors concluded that newborns are prenatally exposed to all metabolites of inorganic As.
RESPIRATORY DISEASE | PM2.5, PAHs, and Bronchitis in Preschool Children
To examine rates of lower respiratory illnesses in preschool children in relation to ambient particles and hydrocarbons, Hertz-Picciotto et al. (p. 1510) evaluated bronchitis in children from two Czech districts: Teplice (with high ambient air pollution) and Prachatice (characterized by lower exposures). Ambient PAHs and fine particles were associated with early-life susceptibility to bronchitis. Associations were stronger for longer pollutant-averaging periods and, among children > 2 years of age, for PAHs compared with fine particles. Preschool-age children may be particularly vulnerable to air pollution–induced illnesses.
Also see Science Selections, p. A504
REPRODUCTIVE HEALTH | Flame Retardants and Cryptorchidism
Polybrominated diphenyl ethers (PBDEs) are widely used in Western countries. Because the prevalence of cryptorchidism appears to be increasing, Main et al. (p. 1519) investigated whether exposure to PBDEs was associated with testicular maldescent. In a prospective Danish–Finnish study in 1997–2001, all boys were examined for cryptorchidism. Two different matrices were used for prenatal PBDE exposure: Levels in breast milk, but not in placenta, showed an association with congenital cryptorchidism. Other environmental factors may contribute to cryptorchidism, and human exposure to PBDEs is high in some geographic areas.
EXPOSURE ASSESSMENT | Urinary Mercury from Dental Amalgam in Children
Urinary mercury concentrations are widely used to measure mercury exposure from dental amalgam fillings, but no studies have evaluated the relationship of these measures in a longitudinal context in children. In an evaluation of urinary mercury in children (8–18 years of age), Woods et al. (p. 1527) found that urinary mercury concentrations are highly correlated with both the number of amalgam fillings and the time since placement over a 7-year course of amalgam treatment in children. Girls excrete significantly higher concentrations of mercury in the urine than boys with comparable treatment, suggesting possible sex-related differences in mercury handling and susceptibility to mercury toxicity.
