Environews
Roundtable Wrap-up
The NIEHS News (p. A28) describes the activities of the past year's NIEHS-cosponsored Institute of Medicine Roundtable on Environmental Health Sciences, Research, and Medicine. It's been a year packed with productive discussion on the future of environmental health research. In other news, participants at a recent institute symposium shared new data on environmental contributors to asthma.
Getting an Earful: Noise Pollution
Sounds are all around us, and when they become loud enough, prolonged enough, or otherwise annoying enough, they become "noise." The Focus (p. A34) discusses the world's noise burden and looks at why the world has become so loud--and how it's affecting our health.
Too Quiet on the Regulatory Front?
As the sound level rises around the United States, it becomes ever more apparent that people suffering from noise pollution--the aural version of secondhand smoke--often have no recourse. Although the U.S. Environmental Protection Agency once had an office devoted to noise control, presidential reform pulled the plug on federal funding for enforcing noise laws. The Spheres of Influence (p. A42) examines the state of the legislature today as it regards noise.
Lowering the Boom
It's well established that noise is a problem--so what do we do about it? The Innovations (p. A46) looks at several techniques and technologies being used to clamp down on the sound emissions of airplanes, highways, lawn equipment, and other sources of noise.
Research
Radiation and Chronic Lymphocytic Leukemia
The U.S. government has implemented rules for compensation to individuals with cancer who were exposed to radiation in the nuclear weapons complex; chronic lymphocytic leukemia (CLL) is considered a nonradiogenic form of cancer and is therefore not eligible for compensation. Richardson et al. (p. 1) review molecular, clinical, and epidemiologic evidence regarding the radiogenicity of CLL. There is a mechanistic basis for expecting that ionizing radiation exposure increases CLL risk, and epidemiologic findings are consistent with the hypothesis of CLL mortality risk following a latency and morbidity period spanning decades. The authors found no persuasive evidence that CLL is a nonradiogenic form of cancer.
Estrogenic PAH Metabolites from Colon Microbiota
Polycyclic aromatic hydrocarbons (PAHs) enter the human body via ingestion, but nothing is known about PAH transformation by human intestinal microbiota. Using a gastrointestinal simulator, Van de Wiele et al. (p. 6) show that human intestinal microbiota can bioactivate PAHs to estrogenic metabolites. Stomach and small intestine digestions of PAH compounds showed no estrogenic effects in the human estrogen receptor bioassay. In contrast, colon digests of the same PAHs displayed estrogenicity. Inactivating the colon microbiota eliminated these estrogenic effects.
Blood Brevetoxin in Striped Mullet
There is a critical need to reliably and routinely monitor brevetoxins in the blood of humans and aquatic animals. Woofter et al. (p. 11) used striped mullet as laboratory test animals to characterize blood brevetoxin during exposure to the brevetoxin-producing dinoflagellate Karenia brevis. Time point blood samples were taken and applied to blood collection cards for brevetoxin analysis using radioimmunoassay. The study demonstrates an effective method for monitoring blood brevetoxin levels in finfish and provides a means to characterize brevetoxin in other species impacted by red tide events.
Synthetic Musk Compounds as MXR Inhibitors
Synthetic musk compounds have been detected in human tissue and in aquatic organisms such as fish and mollusks, but the toxicity and environmental risks are generally regarded as low. However, Luckenbach and Epel (p. 17) show that nitromusks and polycyclic musks inhibit the activity of multidrug efflux transporters responsible for multixenobiotic resistance (MXR) in gills of the marine mussel Mytilus californianus. The inhibitory effects of a brief 2-hr exposure to musks were only partially reversed after a 24- to 48-hr recovery period in clean seawater. (Also see Science Selections, p. A50)
Autoimmune Responses with Asbestos Exposure
Systemic autoimmune responses are associated with exposures to crystalline particles such as silica. Pfau et al. (p. 25) explored the possibility of exacerbated autoimmune responses using markers in age- and sex-matched serum samples collected from Libby, Montana, where exposures have resulted from mining asbestos-contaminated vermiculite, in comparison with samples from Missoula, Montana. In the Libby samples, positive correlations were found between antinuclear antibody titers and both lung disease severity and extent of exposure. Results support the hypothesis that asbestos exposure is associated with autoimmune responses and suggest a relationship with asbestos-related disease processes. (Also see Science Selections, p. A51)
Blood Lead and Homocysteine
Lead and homocysteine are both associated with cardiovascular disease and cognitive dysfunction. Schafer et al. (p. 31) used a cross-sectional analysis of data among subjects in the Baltimore Memory Study to investigate the relations among blood lead, tibia lead, and homocysteine levels. After adjustment for age, sex, race/ethnicity, educational level, tobacco and alcohol consumption, and body mass, results revealed that homocysteine levels increased 0.35 µmol/L per 1.0 µg/dL increase in blood lead. The findings suggest that homocysteine could be a mechanism that underlies the effects of lead on the cardiovascular and central nervous systems.
Uric Acid in Lead Workers
Uric acid and lead may be nephrotoxic at lower concentrations than previously recognized. Weaver et al. (p. 36) analyzed data from current and former lead workers to determine whether lead biomarkers were associated with uric acid and whether associations between lead dose and renal outcomes were altered after adjustment for uric acid. The data suggest that older workers comprise a susceptible population for increased uric acid due to lead. Uric acid may be one, but not the only, mechanism for lead-related nephrotoxicity.
Dioxin TEF Evaluation
The dioxin toxic equivalency factor (TEF) assumes that the combined effects of dioxin-like compounds can be predicted based on a potency-adjusted dose-additive combination. Walker et al. (p. 43) evaluated the TEF approach in experimental 2-year rodent cancer bioassays using 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 3,3´,4,4´,5-pentachlorobiphenyl (PCB-126), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF), or a mixture of the three compounds. The dose responses were the same in studies of the three individual chemicals and the mixture, and support the use of the TEF approach for dioxin cancer risk assessments.
Glyphosate and Cancer Incidence
Glyphosate is one of the most frequently applied pesticides in the world, and a few epidemiologic reports suggest potential health effects. De Roos et al. (p. 49) evaluated associations between glyphosate exposure and cancer incidence in the Agricultural Health Study (AHS), a prospective cohort study of licensed pesticide applicators. Glyphosate exposure was not associated with cancer incidence overall or with most of the cancer subtypes studied. There was a suggested association with multiple myeloma incidence that should be followed up as more cases occur in the AHS.
Impacts of Co-solvent Flushing on Soil Microorganisms
Ramakrishnan et al. (p. 55) assessed the impact of ethanol flushing on trichloroethylene-degrading microbial populations present in aquifer soils taken immediately after and 2 years after ethanol flushing of a former dry cleaner site. Results indicated that impacts of ethanol were not as severe as anticipated and imply that ethanol may mitigate the toxicity of trichloroethylene to the microorganisms.
Biomarkers of Anaerobic Hydrocarbon Biodegradation
Basic research has led to the development of methods for detecting in situ biodegradation of petroleum-related pollutants in anoxic groundwater. Young and Phelps (p. 62) show that 2-methylbenzylsuccinate can be used as a reliable indicator of anaerobic toluene degradation. Field studies confirmed that the biomarker is detectable in field samples that correspond to areas where active biodegradation is predicted. For naphthalene, three biomarkers were identified (2-naphthoic acid, tetrahydro-2-naphthoic acid, and hexahydro-2-naphthoic acid) that can be used in the field to identify areas of active in situ degradation.
Uranium in Drinking Water and Bone
Ingested uranium accumulates in bone and affects bone metabolism in laboratory animals. Kurttio et al. (p. 68) studied men and women 26-83 years of age who had used drinking water originating from wells drilled in bedrock in areas with naturally high uranium content. Results suggest that elevation of serum type I collagen carboxy-terminal telopeptide and osteocalcin could be associated with increased uranium exposure in men, but no similar relationship was found among women. Bone may be a target of chemical toxicity of uranium in humans; therefore, detailed evaluation is warranted.
Benefits of Attaining the 8-Hr Ozone Standard
Each year during 2000-2002, between 36-56% of ozone monitors in the United States failed to meet the ozone standard of 80 ppb for the fourth highest maximum 8-hr ozone concentration. Hubbell et al. (p. 73) estimated the health benefits of attaining the ozone standard at these monitors. The simple average of health impacts across the 3 years includes reductions of 800 premature deaths, 4,500 hospital and emergency room admissions, 900,000 school absences, and over a million minor restricted activity days.
PCBs, Dietary Fat, and Atherosclerosis
Dietary fat can modify the cytotoxicity of polychlorinated biphenyls (PCBs), and coplanar PCBs can induce inflammatory processes of vascular diseases. Hennig et al. (p. 83) tested the hypothesis that interactions of PCBs with dietary fat are dependent on the type of fat by injecting PCB-77 into LDL-R-/- mice fed diets enriched with either olive oil or corn oil. Vascular cell adhesion molecule-1 expression in aortic arches was not detectable in the mice fed olive oil but was highly expressed in the presence of PCB-77. These findings have implications for understanding how the interactions of nutrients with environmental contaminants affect the pathology of inflammatory diseases.
Exposure-Response Relationships of Ambient Particles and Mortality
Samoli et al. (p. 88) investigated the exposure-response association between ambient particles and mortality in the 22 European cities. This association could be adequately estimated using the linear model. The heterogeneity found in the different city-specific relations reflects real effect modification, which can be partly explained by factors characterizing the air pollution mix, climate, and the health of the population.
Environmental Medicine
Squamous Cell Carcinoma in a Railroad Worker
Carlsten et al. (p. 96) describe a 50-year-old male railroad worker who presented to his primary care physician with an erythematous, tender skin lesion on the right knee. Biopsy revealed squamous cell carcinoma in situ. The site of the lesion was sun-protected but was associated with 30 years of creosote-soaked clothing. The authors review dermal and other malignancies associated with creosote, along with creosote occupational exposures and exposure limits. This is a unique case report, given the lack of other potentially confounding polyaromatic hydrocarbons and the sun-protected location of the lesion.
Children's Health
ETS Exposure and Child Cognition
Yolton et al. (p. 98) used the Third National Health and Nutrition Examination Survey conducted from 1988 to 1994, to investigate the relationship between environmental tobacco smoke (ETS) exposure and cognitive abilities among U.S. children 6-16 years of age. A log-linear analysis was the best fit to characterize the increased slope in cognitive deficits at lower levels of exposure. The results indicate an inverse association between ETS exposure and cognitive deficits among children, even at extremely low levels of exposure. (Also see Science Selections, p. A50)
Bone Lead in Children and Lead Abatement Efficacy
Measures to reduce children's household lead exposures often result in only limited reductions in blood lead levels. Gwiazda et al. (p. 104) present an isotopic approach to estimate the magnitude of the bone lead contribution to blood in children following household lead remediation. Results from a limited number of cases support the hypothesis that the release of bone lead into blood may substantially buffer the decrease in blood lead levels expected from the reduction in lead intake.
Fluoride Exposure and Risk of Children
Dental fluorosis in the United States has increased during the last 30 years. Erdal and Buchanan (p. 111) use a mathematical model commonly employed by the U.S. EPA to estimate average daily intake of fluoride via all exposure pathways contributing to fluorosis risk to children living in communities with fluoridated and nonfluoridated water. The theoretical estimates are in good agreement with measurement-based estimates and suggest that a segment of the child population may likely be at risk for fluorosis.
[Table of Contents]
Last Updated: December 15, 2004
