Environews
Summer Science Sizzles
For many students, the summer months are a time to work a short-term job, earn a little money, and gain useful work skills in preparation for a future career. This month's NIEHS News (p. A94) looks at institute-funded summer research programs geared toward high school and college students, as well as their teachers. Programs such as the institute's own Summers of Discovery and other offerings at NIEHS centers around the country are helping the scientists of today grow the scientists of tomorrow.
All Systems Go
A global effort is under way to revolutionize our understanding of the Earth and its ecosystems as an interrelated whole. The Focus (p. A98) describes the Global Earth Observation System of Systems, which seeks to unite Earth-observing capabilities such as satellites with ground-based data-gathering systems. The resulting system of systems is envisioned as a way to more fully understand the interactions of broad forces in nature.
A Plan for Ocean Policy
The U.S. Commission for Ocean Policy has released its final report, An Ocean Blueprint for the 21st Century, and thereby discharged its presidential duty. The picture is grim: the United States is in desperate need of a focused, coherent ocean management policy, states the report, and there is much work to be done before such a policy can be achieved and enacted. The Spheres of Influence (p. A106) reviews the recommendations and findings set forth by the report.
Water Strategies for Space--and Earth, Too
Astronauts aren't allotted much water for daily use--a bare half-gallon or so. But even that small amount can cost more than $50,000 to lift into orbit. At that price, it's imperative that aerospace engineers find a way to literally pull water out of thin air. The Innovations (p. A110) examines space travel strategies for water production that--while designed for the stars--may someday aid the growing number of areas on Earth where water is scarce.
Research
Investments in Large-Scale Prospective Cohorts and Biobanks
Prospective cohorts and biobanks constitute significant, long-term investments in research infrastructure, with ongoing consequences and opportunities for biomedical research. Foster and Sharp (p. 119) suggest that these additions may come at the price of concealing contributors to complex diseases that are less common across all the participants in those larger studies, and of limiting hypothesis generation. These large investments need to be more productive in generating hypotheses and in identifying genetic and environmental factors that are more frequent within subsets.
Developmental Neurotoxicity of Pyrethroids
Pyrethroid insecticides account for 25% of the worldwide insecticide market. Shafer et al. (p. 123) review the scientific data related to potential for age-dependent and developmental neurotoxicity of pyrethroids. Many studies suffer from inadequate study design, problematic statistical analyses, use of formulated products, and/or inadequate controls, all of which confound interpretation of results. Additional developmental neurotoxicity studies should employ methods that promote understanding of the mode of action in the developing nervous system.
Airborne Drug-Resistant Bacteria in a Swine CAFO
It is unclear whether the air within swine operations serves as a source of exposure to antibiotic-resistant bacterial pathogens. Chapin et al. (p. 137) sampled the air within a swine CAFO (concentrated animal feeding operation) and analyzed enterococcus and coagulase-negative staphylococci isolates for resistance to erythromycin, clindamycin, virginiamycin, tetracycline, and vancomycin. Regardless of bacterial species, 98% of the isolates expressed high-level resistance to at least two antibiotics. Inhalation of air from these facilities may transfer multidrug-resistant bacterial pathogens from swine to humans. (Also see Science Selections, p. A116)
Topophilia and the Quality of Life
Ogunseitan (p. 143) tested the hypothesis that individual preferences for ecosystem components and restorative environments are associated with quality of life (QOL). Human subjects responded to a questionnaire on topophilia and to the World Health Organization's QOL instrument. Factor analyses revealed four domains of topophilia (ecodiversity, synesthetic tendency, cognitive challenge, and familiarity) and four domains of QOL (physical, psychological, social, and environmental). Synesthetic tendency was the strongest domain of topophilia, whereas the psychological aspect of QOL was the strongest. Results provide a new framework for linking environmental quality and human health and for implementing restorative targeted design of built environments. (Also see Science Selections, p. A117)
Developmental Exposure to Low-Dose PBDE-99
Polybrominated diphenyl ethers (PBDEs) are a widely used class of persistent flame retardants. Kuriyama et al. (p. 149) assessed juvenile basal motor activity and adult male reproductive health following exposure of Wistar dams to PBDE-99 on gestation day 6. Exposure to low-dose PBDE-99 (60or 300µg/kg body weight) during development caused hyperactivity in the offspring and permanently impaired spermatogenesis. The doses used in this study are approximately 6 and 29 times higher than the highest level reported in human breast adipose tissue.
Estimation of Maternal Methyl Mercury Intake Dose
The U.S. Environmental Protection Agency (EPA) has adopted a reference dose for methyl mercury of 0.1 µg/kg/day based on effects measured in children from in utero exposure. The dose reconstruction used by the U.S. EPA does not account for the ratio of cord blood:maternal blood Hg concentration and does not resolve central tendency estimates for pregnancy and third-trimester parameters. Stern (p. 155) has reassessed the dose reconstruction based on review and recalculation. It was estimated that the lower 5th and 1st percentiles of the maternal intake dose, corresponding to a fetal cord blood Hg concentration of 58 µg/L, are 0.3 and 0.2 µg/kg/day, respectively. For the 99th percentile, this is half the value previously estimated by the U.S. EPA.
Metals and Peripheral Arterial Disease
Exposure to metals may promote atherosclerosis. In the 1999-2000 National Health and Nutrition Examination Survey (NHANES), blood cadmium and lead were associated with peripheral arterial disease (PAD). Navas-Acien et al. (p. 164) evaluated the association between urinary levels of cadmium, lead, barium, cobalt, cesium, molybdenum, antimony, thallium, and tungsten with PAD in a cross-sectional analysis of participants
40 years of age in NHANES 1999-2000. Urinary cadmium, tungsten, and possibly antimony were associated with PAD in a representative sample of the U.S. population; other metals in urine were not associated with PAD at the levels found in the general population.
Carbon and Carbon/Iron Cytotoxicity
Long et al. (p. 170) tested the hypothesis that iron in carbon particulates enhances ultrastructural perturbation in human monocyte-derived macrophages (MDM) following phagocytosis. Cultures of human MDM or T lymphocytes (as a nonphagocytic control) were exposed to carbon or carbon/iron 1µm synthetic carbon-based particulates and examined by transmission electron microscopy. Results suggest that, among particulates of similar size, biological activity can vary profoundly as a function of particulate physicochemical properties.
PCB, p,p´-DDE and Sperm Chromatin Structure
Rignell-Hydbom et al. (p. 175) explore the hypothesis that exposure to polychlorinated biphenyls (PCBs) and dichlorodiphenyldichloroethylene (p,p´-DDE), the major metabolite of dichlorodiphenyltrichloroethane (DDT), is associated with altered human sperm chromatin structure among Swedish fishermen. The authors determined serum levels of 2,2´,4,4´,5,5´-hexachlorobiphenyl (CB-153) and p,p´-DDE and used the sperm chromatin structure assay (SCSA) to assess sperm DNA/chromatin integrity. A significantly lower DNA fragmentation index (%DFI) was found in the lowest CB-153 quintile compared with the other quintiles. There was a similar tendency, although not statistically significant, between %DFI and p,p´-DDE.
Biological Activity of Remediation Products
Bioremediation is usually assessed from the loss of the chemical of interest. Little is known about the effect of remediation on toxicity to mammalian organisms. Ganey and Boyd (p. 180) discuss an approach using mammalian cell bioassays to evaluate the biological response to mixtures of polychlorinated biphenyls before and after remediation by reductive dechlorination. The results demonstrate the potential to assess the impact of remediation on a range of biological activities in mammalian cells and thus to estimate the effects of remediation strategies on toxicity.
Microbial Biomarkers
New Bedford Harbor (NBH), Massachusetts, is a heavily contaminated U.S. EPA-designated Superfund site. Microorganisms are thought to contribute to the fate and distribution of contaminants in NBH through a variety of mechanisms, including direct transformations and formation of soluble and insoluble species. Ford et al. (p. 186) discuss changes in microbial community structure and function in response to exposure to toxic contaminants, with the ultimate goal of using microbes as ecotoxicological tools.
Urinary Creatinine Concentrations in the United States
Urinary biomonitoring data are typically adjusted to a constant creatinine concentration to correct for variable dilutions among spot samples. Traditionally, this approach has been used in population groups with little diversity. Barr et al. (p. 192) examined the impact of variations in creatinine concentrations among demographic groups on classifying exposure status. For multiple regression analysis of population groups, the unadjusted analyte concentration should be included in the analysis, with urinary creatinine added as a separate independent variable. This approach allows the statistical significance of other variables in the model to be independent of effects of creatinine concentration.
Air Pollution and Atherosclerosis
Long-term exposure to ambient air pollution is associated with cardiovascular morbidity and mortality. Animal data suggest that ambient particulate matter (PM) may contribute to atherogenesis. Künzli et al. (p. 201) investigated the association between atherosclerosis and long-term exposure to ambient PM
2.5µm in diameter (PM2.5) among participants from two clinical trials. Baseline data included assessment of the carotid intima-media thickness (CIMT), a measure of subclinical atherosclerosis. The authors geocoded subjects' residential areas in order to assign annual mean concentrations of ambient PM2.5. Among subjects
60 years of age, women, never smokers, and those reporting lipid-lowering treatment at baseline, the associations of PM2.5 and CIMT were larger; the strongest associations were found in women. (Also see Science Selections, p. A116)
Environmental Medicine
Arsenic Exposure in Chinese Traditional Medicine
Chronic arsenic toxicity occurs primarily through inadvertent ingestion or occupational exposure, but it can also occur through medicinal ingestion. Lee and Bebb (p. 207) review the case of a 53-year-old male treated for 10years in childhood with Chinese traditional medicine containing arsenic. He was diagnosed with Bowen's disease and developed extensive-stage small-cell carcinoma of the lung 10years and 47years, respectively, after the onset of arsenic exposure. Individuals with documented arsenic-induced Bowen's disease should be considered for more aggressive screening for the development of subsequent malignancies.
Children's Health
Chlorpyrifos Accumulation Patterns
Hore et al. (p. 211) investigated the in-home distribution of chlorpyrifos for a 2-week period following a professional crack-and-crevice application and determined the amount of chlorpyrifos absorbed by a child within the home. The authors measured pesticides in indoor air and on indoor surfaces and plush toys, as well as in morning urine samples collected from children. Chlorpyrifos concentrations in and on the plush toys increased throughout the period, demonstrating a cumulative adsorption/absorption process. There was no significant increase in the amount of chlorpyrifos absorbed by the children.
Organochlorine Pesticides and Male Genital Anomalies
Bhatia et al. (p. 220) conducted a case-control study of serum levels of p,p´-dichlorodiphenyltrichloroethane (DDT) and its major metabolite p,p´-dichlorodiphenyldichloroethylene (DDE) and the incidence of cryptorchidism and hypospadias in a longitudinal cohort of pregnancies that occurred between 1959 and 1967. Overall, the authors observed no statistically significant relationships or trends between outcomes and serum measures of DDT or DDE.
Chlorination By-products and Adverse Birth Outcomes
Toledano et al. (p. 225) investigated the associations of total trihalomethanes (TTHMs) and individual THMs with risk of stillbirth and low birth weight in three water regions in England during 1992-1998. Overall summary estimates across the three regions using a random-effects model showed small excess risks in areas with high TTHMs. Among the individual THMs, chloroform showed a similar pattern of risk as TTHMs. Findings overall suggest an association of stillbirths with maternal residence in high TTHM areas, but further work needs to differentiate between alternative explanations and those that may be due to the water supply.
Toxicogenomics
Blood Gene Expression Profiles and Metal-Fume Exposure
Particulate air pollutants can cause both pulmonary and airway inflammation, but few data show that particulates induce systemic inflammatory responses. Wang et al. (p. 233) analyzed gene expression using whole-blood total RNA from boilermakers before and after occupational exposure to metal fumes. Genes with altered expression in response to particulate exposure were clustered in inflammatory response, oxidative stress, intracellular signal transduction, cell cycle, and programmed cell death.
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Last Updated: January 19, 2005