Environews
NIEHS NEWS | NIEHS Strategic Plan: New Frontiers in Environmental Sciences and Human Health
Under the helm of a new leader, the NIEHS is reexamining, redirecting, and reinvigorating its trajectory, to clearly define where the institute is today, where it wants to go over the next five years, and how it intends to get there. This article (p. A280) describes the key components of and response to the recently released NIEHS Strategic Plan, a blueprint that will guide evaluation and decision making as the institute strives to achieve its vision of using environmental sciences to understand human disease and improve human health.
FOCUS | Putting the Earth in Play: Environmental Awareness and Sports
Sports participation and spectatorship has long provided us with relaxation, exercise, and entertainment. But even though these social and physical benefits are indisputable, how are we affecting our environment when we engage in sporting activities? This article (p. A286) discusses the environmental impact of the sports industry, and looks at the movement gaining momentum to increase awareness of and ease the burden posed by enjoying our favorite pastimes.
SPHERES OF INFLUENCE | The Regulation Equation: Factoring In the Price of Health
How do you assign a dollar value to someone's health and age? Is it even fair or reasonable to do so? These are only two of the questions policy makers must ask when examining the benefits and costs of new or existing regulations. This article (p. A296) examines the cost effectiveness analysis method currently used by the U.S. Office of Management and Budget in policy decisions and describes recommendations for improvements offered by a new Institute of Medicine report.
INNOVATIONS | Biogas: A Bright Idea for Africa
With limited access to energy sources commonly used in industrialized nations, residents in the developing world must often depend on energy supplies that can be scarce or hazardous to their health. One response to this deficiency--biogas--offers a simple yet effective means of energy generation that also imparts environmental benefits. This article (p. A300) takes a look at the emerging renewable energy technology that's responding to resource needs by converting human and animal waste directly into power for use in homes.
Review
DIABETES | Systematic Review of Arsenic and Diabetes
Chronic arsenic exposure has been suggested to contribute to diabetes development. Navas-Acien et al. (p. 641) systematically reviewed the experimental and epidemiologic evidence on the association of arsenic and type 2 diabetes. The evidence was inconsistent from both occupational studies and general populations other than those reported in Taiwan or Bangladesh. The evidence was not adequate to establish a causal role of arsenic in diabetes. Because arsenic exposure is widespread and diabetes prevalence is reaching epidemic proportions, experimental studies that use arsenic concentrations relevant to human exposure and prospective epidemiologic studies that measure arsenic biomarkers and appropriately assess diabetes should be a research priority.
Research
EXPOSURE ASSESSMENT | Factors Affecting Personal-Ambient Associations
Air pollution exposure assessment suggests that ambient fine particles, but not ambient gases, are proxies of corresponding personal exposures. For particles, the strength of the personal-ambient association can differ by particle component and level of home ventilation. For gases, the impact of home ventilation is untested. Sarnat et al. (p. 649) found strong associations between ambient particle concentrations and corresponding personal exposures. The results suggest that ventilation may be an important modifier of the magnitude of effect in time-series health studies, and that results from time-series health studies based on 24-hr ambient concentrations are more readily interpretable for particles than for gases.
CARDIOVASCULAR DISEASE | Source-Specific PM2.5 and Myocardial Ischemia
Epidemiologic studies have shown that ambient particulate matter (PM) has adverse effects on cardiovascular health. Effective mitigation of the health effects requires identification of the most harmful PM sources. Lanki et al. (p. 655) evaluated relative effects of fine PM from different sources on exercise-induced ischemia. Forty-five elderly nonsmoking persons with stable coronary heart disease visited a clinic biweekly for submaximal exercise testing, during which the occurrence of ST segment depressions was recorded. Results suggest that the PM fraction originating from combustion processes, notably traffic, exacerbates ischemic heart diseases associated with PM mass.
ENVIRONMENTAL TOXICOLOGY | Maternal Transfer of Contaminants in Amphibians
Global amphibian populations are declining at alarming rates, and several factors have been implicated. Environmental contamination may have particularly important effects on sensitive developmental stages. Hopkins et al. (p. 661) examined maternal transfer of contaminants in eastern narrow-mouth toads (Gastrophryne carolinensis) collected from a reference site and near a coal-burning power plant. Adult toads transferred significant quantities of selenium and strontium to their eggs. Although there was no statistical relationship between the concentration of Se or Sr transferred to eggs and offspring viability, the study demonstrates that maternal transfer may be an important route of contaminant exposure in amphibians.
NEURODEVELOPMENT | Effects of Chlorpyrifos
The organophosphate insecticide chlorpyrifos (CPF) adversely affects mammalian brain development through multiple mechanisms. Jameson et al. (p. 667) exposed PC12 cells to CPF to determine if CPF affects neuron replication and phenotype, and to identify the vulnerable stages of differentiation. CPF exerts stage-specific effects, reduces DNA synthesis in the undifferentiated state, impairs development of the cholinergic phenotype at the start of differentiation, and promotes the catecholaminergic phenotype both in undifferentiated and differentiated cells. CPF administration produces deficits in the number of neurons and cholinergic function in vivo and in vitro, suggesting that CPF directly influences the phenotypic fate of neuronal precursors.
Also see Science Selections, p. A304
BIOMONITORS | Biomarkers of Coke Oven Emission Exposure
Liu et al. (p. 673) recruited coke oven workers and control subjects from a plant in northern China to investigate associations among occupational exposure to coke oven emissions (COEs), oxidative stress, cytogenotoxic effects, changes in glutathione S-transferase (GST), and internal levels of polycyclic aromatic hydrocarbons (PAHs). Multivariate logistic regression analysis revealed that exposure to COEs had the highest odds ratio among variables analyzed and that smoking was not a significant confounder of the levels of studied biomarkers. Overall, the present findings suggest that COE exposure led to increased internal PAH burden, genetic damage, oxidative stress, and GST activity.
INFECTIOUS DISEASE | Weather Variability and Barmah Forest Virus Disease
Naish et al. (p. 678) examined the impact of weather variability and tides on the transmission of Barmah Forest virus (BFV) disease and developed a weather-based forecasting model for BFV disease in the Gladstone region, Australia. Seasonal autoregressive integrated moving-average (SARIMA) models were used to determine the contribution of weather variables to BFV transmission after the time-series data of response and explanatory variables were made stationary through seasonal differencing. The SARIMA model shows that the 5-month moving average of minimum temperature was statistically significantly and positively associated with BFV disease, whereas high tide in the current month was statistically significantly and inversely associated with this disease.
TOXICOLOGY | Oxidative Properties of PM2.5 across Europe
The redox activity of particles has been proposed to represent a major determinant of their toxicity. Künzli et al. (p. 684) measured the in vitro ability of ambient fine particles to form hydroxyl radicals in an oxidant environment and their ability to deplete physiologic antioxidants in the naturally reducing environment of the respiratory tract. PM oxidative activity varied significantly, and correlations with other characteristics of PM were low. These novel measures reflect crucial biologic mechanisms of PM and their use may be relevant in epidemiologic studies; therefore, appropriate methods to determine oxidative activity of PM need to be established.
NEUROBEHAVIORAL DISEASE | Organophosphate Pesticides and Neurobehavioral Performance
Our understanding of the health risks of farmworkers exposed to pesticides in their work and home environments is rapidly increasing, but studies designed to examine the possible neurobehavioral effects of low-level chronic pesticide exposure are limited. Rothlein et al. (p. 691) measured urinary levels of dialkyl phosphate metabolites, collected dust samples from homes, obtained information on work practices, and conducted neurobehavioral tests on farmworkers in Oregon. Performance was lower for Hispanic immigrant farmworkers than for the nonagricultural Hispanic immigrant population. Within the sample of agricultural workers, there was a positive correlation between urinary levels of organophosphate metabolites and poorer performance on some neurobehavioral tests.
GENE EXPRESSION | Estrogenic Activity of Gas-Phase Air Contaminants
Adverse health effects are linked to particulate matter exposure in ambient air. Using aryl hydrocarbon receptor (AHR) and estrogen receptor (ER)-based cell bioassay systems, Klein et al. (p. 697) assessed the dioxin-like and estrogenic activities of gas-phase organic ambient air contaminants compared with those of particulate-phase contaminants. Gas-phase samples induced significant AHR- and ER-dependent gene expression. In the estrogen assay, the activity of gas-phase samples was greater than that of particulate-phase samples. The authors found no strong associations between either summer or winter, or urban or rural locations in the relative efficacy of the extracts in either the ER or AHR assay, despite differences in chemical composition, concentration, and abundance.
ENVIRONMENTAL TOXICOLOGY | Infectious Disease and PCBs in Harbor Porpoise
Using a case-control study design, Hall et al. (p. 704) determined whether the risk of mortality from infectious disease in harbor porpoise in U.K. waters increased with exposure to polychlorinated biphenyls (PCBs). For each 1 mg/kg increase in blubber PCBs, the average increase in risk of infectious disease mortality was 2%. A doubling of risk occurred at approximately 45 mg/kg lipid. The authors endeavored to avoid selection bias by using controls that died of physical trauma as representative of the exposure prevalence in the population that gave rise to the cases.
INFECTIOUS DISEASE | Infection Risk of Divers
Divers run a higher risk of infection with waterborne pathogens than bathers because of more frequent and intense contact with water that may not comply with microbiologic water quality standards. Schijven and de Roda Husman (p. 712) estimated the volume of water swallowed as a key factor for infection risk assessment associated with diving. From the volumes of swallowed water and concentrations of pathogens in fecally contaminated water, they estimated the infection risks per dive and per year to be as high as a few to up to tens of percents. It is highly recommended that divers be informed about contaminated diving conditions.
Also see Science Selections, p. A304
REPRODUCTIVE HEALTH | POPs and Sperm Sex Chromosome Ratio
Recent studies indicate that persistent organohalogen pollutants (POPs) may contribute to sex ratio changes in offspring of exposed populations. Tiido et al. (p. 718) investigated whether exposure to 2,2´,4,4´,5,5´-hexachlorobiphenyl (PCB-153) and dichlorodiphenyldichloroethene (p,p´-DDE) affects sperm Y:X chromosome distribution. They analyzed PCB-153 and p,p´-DDE levels in semen and blood samples obtained from 547 men from Sweden, Greenland, Poland (Warsaw), and Ukraine (Kharkiv), with regionally different levels of POP exposure. The authors found that POP exposure might be involved in changing the proportion of ejaculated Y-bearing spermatozoa in human populations and that intercountry differences, with different exposure situations and doses, may contribute to varying Y:X chromosome ratios.
RESPIRATORY DISEASE | Health Effects of Sugar Cane Burning
Cançado et al. (p. 725) analyzed the influence of emissions from burning sugar cane on the respiratory systems of citizens of Piracicaba, Brazil. Samples of inhalable particles, separated into fine and coarse particulate mode, were analyzed for black carbon and tracer elements. The authors examined daily records of children and elderly people admitted to the hospital because of respiratory diseases and found that effects on respiratory hospital admissions were much higher during the burning period. The results show that sugar cane-burning emissions have an adverse impact on the health of the population, reinforcing the need for public efforts to reduce this source of air pollution.
CARDIOVASCULAR DISEASE | Geochemistry of Well Water and AMI Incidence
Several epidemiologic studies have shown an association between calcium and magnesium and coronary heart disease mortality and morbidity. Kousa et al. (p. 730) examined the relationship between acute myocardial infarction (AMI) risk and content of Ca, Mg, and chromium in groundwater in Finnish rural areas using Bayesian modeling and geospatial data. Results support earlier findings of a protective role of Mg and low Ca: Mg ratio against coronary heart disease but do not support the hypothesis of a protective role of Ca.
TOXICOLOGY | Neonatal Mercury Accumulation
Exposure of pregnant rats to elemental mercury (Hg0) vapor causes significant accumulation of Hg in tissues of neonates. Because elevated Hg in neonatal tissues may adversely affect growth and development, Morgan et al. (p. 735) investigated how rapidly Hg was eliminated from neonatal tissues. There was no elimination of Hg between birth and weaning, indicating that neonates were exposed continuously to elevated levels of Hg during postpartum growth and development. The data indicate that dietary exposure to trace amounts of Hg can result in a significantly greater accumulation of Hg in neonates than gestational exposure to high concentrations of Hg0 vapor.
ENDOCRINE SYSTEM | Dioxins and Estrogen Metabolism
Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) are environmental endocrine disruptors that have half-lives of 7-10 years in the human body and have toxicities that probably include carcinogenesis. In this cohort study of maternal-fetal pairs, Wang et al. (p. 740) examined the relationship of PCDD/PCDF and PCB exposure to levels of estrogen metabolites in the sera of 50 pregnant women 25-34 years of age from central Taiwan. The study suggests that exposure to PCDDs/PCDFs significantly affects estrogen metabolism. Therefore, PCDD/PCDF exposure must be considered when using the OH-E2 ratio as a breast cancer marker.
NEURODEVELOPMENT | Organophosphate Developmental Neurotoxicity
Slotkin et al. (p. 746) contrasted neuritic outgrowth and cholinergic synaptic development in neonatal rats given different organophosphates (chlorpyrifos, diazinon, parathion) at doses spanning the threshold for impaired growth and viability. The results indicate a complete dichotomy between the systemic toxicity of organophosphates and their propensity to elicit developmental neurotoxicity. For parathion, the threshold for lethality lies below that necessary for adverse effects on brain development, whereas the opposite is true for chlorpyrifos and diazinon.
ENVIRONMENAL TOXICOLOGY | Evaluating Xenoestrogens in Glial Cells
Brain cytochrome P450 aromatase (Aro-B) in zebrafish is expressed in radial glial cells and stimulated by estrogens and can be used as an in vivo biomarker of xenoestrogen effects on the central nervous system. Using quantitative real-time PCR, Le Page et al. (p. 752) confirmed that the expression of Aro-B gene is robustly stimulated after exposure to several xenoestrogens. They developed a glial cell-based assay to investigate the impact of environmental estrogenic chemicals on distinct estrogen receptor (ER) activity. The bioassay provides a fast, reliable, sensitive, and efficient test for evaluating estrogenic potency of endocrine disruptors on ER subtypes in a glial context.
Environmental Medicine
RESPIRATORY DISEASE | A Case of Wood-Smoke-Related Pulmonary Disease
Biomass serves as a major fuel source for > 50% of the world's population. The global burden of disease attributed to indoor air pollution from biomass combustion accounts for approximately 3% of worldwide disability-adjusted life-years lost. Diaz et al. (p. 759) present the case of a man who was referred to a pulmonary clinic for evaluation of chronic productive cough and pulmonary nodules. In his youth, he worked at a charcoal plant in Mexico, where he burned wood and was exposed to massive amounts of smoke. The patient was diagnosed with "hut lung," a noninfectious, nonmalignant respiratory manifestation of chronic, high-level exposures to biomass smoke.
HUMAN TOXICOLOGY | Hepatic Injuries and Hexachloroethane Smoke Inhalation
Loh et al. (p. 763) report on two patients (23- and 24-year-old men) who had chemical pneumonitis and respiratory distress after inhaling hexachloroethane/zinc oxide (HC/ZnO) smoke during military training. Both men were healthy before the exposure. Hematologic tests revealed leukocytosis, with neutrophils predominant. In both patients, the respiratory condition improved after steroid therapy and oxygen support, but deterioration of liver function was found. The authors attributed the hepatotoxic effect to inhalation of high-concentration HC/ZnO smoke in an enclosed area, where several hepatotoxicants (e.g., ZnCl2, HC, chlorinated vapors) could have been generated and mixed in the smoke. These case reports show that hepatic effects may occur in addition to pulmonary effects of HC/ZnO smoke.
Children's Health
ASTHMA | Traffic, Susceptibility, and Childhood Asthma
Results from studies of traffic and childhood asthma have been inconsistent. McConnell et al. (p. 766) examined the relationship of traffic-related exposure and asthma in southern California school children. Residential exposure was assessed by proximity to a major road and by modeling exposure to local traffic-related pollutants. The higher risk of asthma near a major road decreased to background rates at 150-200 m from the road; also, a greater effect of residential proximity to roadways was found in girls. A similar pattern of effects was observed with traffic-modeled exposure. These results indicate that residence near a major road is associated with childhood asthma.
Also see Science Selections, p. A305
NEURODEVELOPMENT | PCBs, Dioxins, and Child Neurodevelopment
Prenatal and/or postnatal background-level exposure to environmental chemicals, such as polychlorinated biphenyls (PCBs) and dioxins, induces adverse effects in some studies of neurodevelopment in children. Other studies have not detected any harmful influences. Except in western countries, no developmental tests have been carried out in relation to detailed assessment of exposure to PCBs and dioxins. Nakajima et al. (p. 773) examined the effects of prenatal exposure to background levels of PCBs and dioxins on infant neurodevelopment in Sapporo, Japan. The background-level exposure of several isomers of dioxins probably affects the motor development of 6-month-old infants more than it does their mental development.
CHILD DEVELOPMENT | Prenatal PCB Exposure and Childhood Growth
Polychlorinated biphenyls (PCBs) are persistent environmental contaminants with suspected endocrine-disrupting properties. PCBs may mimic or inhibit hormone and endocrine processes based in part on their structural configuration. Animal studies link prenatal PCB exposure to adverse birth and early-life growth outcomes, but epidemiologic studies are conflicting. Lamb et al. (p. 779) examined whether prenatal exposure to PCBs affected childhood height and weight attainment in 150 children born at the Columbia-Presbyterian Hospital from 1959 through 1962 to African-American mothers. The results suggest that prenatal exposure to PCBs may affect growth and that ortho-substitution is an important determinant of its effect on growth.
RESPIRATORY DISEASE | Infant Mortality and Air Pollution
Studies suggest that airborne particulate matter (PM) may be associated with postneonatal infant mortality, particularly with respiratory causes and sudden infant death syndrome (SIDS). Woodruff et al. (p. 786) examined the relationship between long-term exposure to fine PM air pollution and postneonatal infant mortality in California. Adjusted odds ratio for a 10-µg/m3 increase in PM2.5 was 1.07 for overall postneonatal mortality, 2.13 for respiratory-related postneonatal mortality, 0.82 for SIDS, and 0.83 for external causes. These findings add further evidence of a PM air pollution effect on respiratory-related postneonatal infant mortality.
NEURODEVELOPMENT | Pregnancy Lead Exposure and Child IQ to 10 Years of Age
Low-level postnatal lead exposure is associated with poor intellectual development in children, although the effects of prenatal exposure are less well studied. Schnaas et al. (p. 791) hypothesize that prenatal lead exposure would have a more powerful and lasting impact on child development than postnatal exposure. Results indicate that lead exposure around 28 weeks gestation is a critical period for later child intellectual development, with lasting and possibly permanent effects. The authors found no evidence of a threshold; the strongest lead effects on IQ occurred within the first few micrograms of BPb.
ENDOCRINE SYSTEM | Perchlorate and California Newborns
Perchlorate (ClO4-) has been detected in groundwater sources in numerous communities in California and other parts of the United States, raising concerns about potential impacts on health. For communities where ClO4- was tested in 1997 and 1998, Buffler et al. (p. 798) evaluated the prevalence of primary congenital hypothyroidism (PCH) and high thyroid-stimulating hormone (TSH) levels among the 342,257 California newborns screened in 1998. Using an assessment of ClO4- in drinking water based on available data, they found no observed association between estimated average ClO4- concentrations > 5 µg/L in drinking water supplies and the prevalence of clinically diagnosed PCH or high TSH concentrations.
