Environews
FOCUS | Carbon Capture and Storage: Blue-Sky Technology or Just Blowing Smoke?
Faced with the threat of global climate change, governments and industries worldwide are exploring new avenues to deal with greenhouse gas emissions. One technique with potential for large-scale use is carbon capture and storage (CCS). However, ensuring continued development and practical application of new processes such as CCS requires a substantial commitment of resources. This article (p. A538) takes a look at the technologies behind CCS as well as some of the technical and logistical questions that remain regarding future implementation.
SPHERES OF INFLUENCE | Of Two Minds: Groups Square Off on Carbon Mitigation
In the midst of concerns about the effects of climate change, carbon capture and storage (CCS) has emerged as a promising method of mitigation. But taking a firm stand toward implementing CCS has prompted concerns among environmental advocacy groups regarding public safety and health. Does CCS present a genuine cause for concern to the public? This article (p. A546) examines the arguments of environmental justice groups against a bill introduced in the California State Legislature seeking, among other goals, to regulate CCS as a means of handling carbon dioxide emissions.
Review
EXPOSURE ASSESSMENT Evaluation of Water Manganese Guidelines
Ljung and Vahter (p. 1533) reviewed the scientific background for the current health-based World Health Organization (WHO) guideline value for manganese in drinking water; this guideline value is based partly on debatable assumptions for which information from previous reports was used without revisiting the original research articles. At present, when water containing Mn concentrations equivalent to the WHO guideline value are used to prepare common infant formula, the Mn concentration will then exceed the maximum allowed in infant formula. Further research is needed to understand the causal relationship between Mn exposure and children's health and to improve risk assessment.
Research
RISK ASSESSMENT | VOCs in Drinking Water from Domestic Wells
As both the population and the demand for safe drinking water from domestic wells increase, it is important to examine water quality and contaminant occurrence. A national assessment in 2006 by the U.S. Geological Survey reported findings for 55 volatile organic compounds (VOCs) based on 2,401 domestic wells sampled during 1985–2002. Rowe et al. (p. 1539) examined the occurrence of individual and multiple VOCs and assessed the potential human-health relevance of VOC concentrations. Drinking water supplied by domestic wells is vulnerable to low-level VOC contamination. About 1% of samples had concentrations of potential human-health concern.
Also see Science Selections, p. A550
NEURODEVELOPMENT | Pentylenetetrazole-Induced Seizures in DA-Exposed Zebrafish
Domoic acid (DA) is a neurotoxin produced by diatoms that target the limbic system to induce tonic–clonic seizures and memory impairment. Tiedeken and Ramsdell (p. 1547) used in ovo microinjection of zebrafish to characterize the effect of embryonic exposure of DA on seizure-inducing agents later in life as an alternative species model to screen environmental contaminants that might induce a fetal-originating adult disease. The study demonstrates that in ovo exposure to DA reduces the threshold to chemically induced seizures in larval fish and increases the severity of seizure behavior in a manner that is consistent with in utero studies of laboratory rodents.
GENE POLYMORPHISM | HLA-B*1301 Associated with TCE Hypersensitivity
Trichloroethylene (TCE), which is used extensively as an industrial solvent, has been recognized as one of the major environmental pollutants. To date, > 200 cases of TCE-induced hypersensitive dermatitis have been reported worldwide among exposed workers, and it has become a critical occupational health issue in Asia. Li et al. (p. 1553) identified genetic susceptible biomarkers associated with TCE-induced hypersensitive dermatitis in genes located in the human leukocyte antigen (HLA) region. The HLA-B*1301 allele is strongly associated with TCE-induced hypersensitive dermatitis among exposed workers and could be used as a biomarker to identify individuals at risk from TCE exposure.
RESPIRATORY DISEASE | MMP-9 Attenuates Lung Injury Caused by O3
Exposure to ozone causes airway inflammation, hyperreactivity, lung hyperpermeability, and epithelial cell injury. An early inflammatory response to inhaled O3 is characterized primarily by release of inflammatory mediators. Matrix metalloproteinases (MMPs) have been implicated in the pathogenesis of oxidative lung disorders including acute lung injury, asthma, and chronic obstructive pulmonary disease. Yoon et al. (p. 1557) demonstrate a protective role of MMP-9, but not MMP-7, in O3-induced lung neutrophilic inflammation and hyperpermeability. The mechanism through which Mmp9 limits O3-induced airway injury may be via posttranscriptional effects on proinflammatory CXC chemokines including KC and MIP-2.
NEURODEGENERATIVE DISEASE | Blood Lead Concentrations in Essential Tremor
Essential tremor (ET) is one of the most common neurologic disorders. Aside from underlying susceptibility genes, recent studies have also begun to focus on environmental toxic factors. A recent study in New York City found elevated blood lead concentrations in ET cases compared with matched controls. Chronic exposure to lead produces cerebellar damage, which could predispose individuals to develop ET. Dogu et al. (p. 1564) determined whether the elevation in blood lead concentrations observed in a single study in New York was similarly present in ET cases sampled from Mersin, Turkey.
CANCER | Water Intake, Disinfection By-Products, and Bladder Cancer Risk
Findings on water and total fluid intake and bladder cancer are inconsistent; this may be attributed partly to different levels of carcinogens in drinking water. High levels of arsenic and chlorinated by-products in drinking water have been associated with elevated bladder cancer risk in most studies. Michaud et al. (p. 1569) examined the association between total fluid and water consumption and bladder cancer risk, as well as the interaction between water intake and trihalomethane (THM) exposure, in a large case–control study in Spain. Findings suggest that water intake is inversely associated with bladder cancer risk, regardless of THM exposure level.
Also see Science Selections, p. A551
BIOMONITORS | Lymphocyte and Plasma Hsp70 in Coke Oven Workers
Hsp70 is an early-response protein induced when organisms are confronted with simple or complicated environmental stresses and can act as either a cellular protector or a danger signal. Yang et al. (p. 1573) evaluated levels of lymphocyte and/or plasma Hsp70 as biomarkers for assessing exposure response to complex coke oven emissions (COEs). High lymphocyte Hsp70 levels may provide protection, whereas high plasma Hsp70 levels may serve as a danger marker in workers exposed to COEs. Larger validation studies are needed to establish the utility of Hsp70 as a response marker.
POPULATION HEALTH | Effects of Carbon Monoxide on Mortality
Samoli et al. (p. 1578) investigated the short-term effects of carbon monoxide on total and cardiovascular mortality in 19 European cities participating in the APHEA-2 (Air Pollution and Health: A European Approach) project. The authors examined the association using hierarchical models implemented in two stages. In the first stage, data from each city were analyzed separately; in the second stage, the city-specific air pollution estimates were regressed on city-specific covariates to obtain overall estimates and to explore sources of possible heterogeneity. The results are consistent with an independent effect of CO on mortality.
RESPIRATORY DISEASE | Newly Diagnosed Asthma among WTC Workers
Studies have consistently documented declines in respiratory health after 11 September 2001 among surviving first responders and other World Trade Center (WTC) rescue, recovery, and clean-up workers. Wheeler et al. (p. 1584) describe newly diagnosed asthma among WTC site workers and volunteers, and characterize its association with WTC site exposures. The rate of self-reported newly diagnosed asthma was high in the study population and was significantly associated with increased exposure to the WTC disaster site. Although the authors could not distinguish appropriate respiratory protection from inappropriate, they observed a moderate protective effect of mask or respirator use.
RISK ASSESSMENT | Sensitivity of Ozone–Mortality Relationship to PM
A critical question regarding the association between short-term exposure to ozone and mortality is the extent to which this relationship is confounded by ambient exposure to particles. Bell et al. (p. 1591) used data for 98 U.S. urban communities from 1987 to 2000 to investigate whether particulate matter (< 10 µm and < 2.5 µm in aerodynamic diameter; PM10 and PM2.5, respectively) is a confounder of the association between ozone and mortality. Results provide evidence that neither PM10 nor PM2.5 is a likely confounder of observed ozone and mortality relationships. Further investigation is needed to examine potential confounding of the short-term effects of ozone on mortality by PM chemical composition.
POPULATION HEALTH | Polyfluoroalkyl Chemicals in the United States in 2003–2004
Polyfluoroalkyl chemicals (PFCs) have been used since the 1950s in numerous commercial applications. Exposure of the general U.S. population to PFCs is widespread. Since 2002, the manufacturing practices for PFCs in the United States have changed considerably. Calafat et al. (p. 1596) assessed exposure to perfluorooctane sulfonic acid, perfluorooctanoic acid, perfluorohexane sulfonic acid, perfluorononanoic acid, and eight other PFCs in a representative 2003–2004 sample of the general U.S. population ? 12 years of age to determine whether serum concentrations have changed since the 1999–2000 National Health and Nutrition Examination Survey.
RISK ASSESSMENT | Mobile Phone Base Stations and Well-Being
Individuals with idiopathic environmental illness with attribution to electromagnetic fields (IEI-EMFs) believe they suffer negative health effects when exposed to EMFs from everyday objects, such as mobile phone base stations. Eltiti et al. (p. 1603) used both open provocation and double-blind tests to determine whether sensitive or control individuals experience more negative health effects when exposed to base station–like signals compared with sham signals. Short-term exposure to a typical global system for mobile communication base station–like signal did not affect well-being or physiologic functions in sensitive or control individuals. Sensitive individuals reported elevated levels of arousal when exposed to a universal mobile telecommunications system signal.
RISK ASSESSMENT | Evaluation and Application of the RD50 for Public Exposure Levels
The test for RD50 (exposure concentration producing a 50% respiratory rate decrease) evaluates airborne chemicals for sensory irritation and has become a standard method for the American Society for Testing and Materials. Past studies reported good correlations (R2) between RD50 values and the occupational exposure limits, particularly threshold limit values. Kuwabara et al. (p. 1609) examined the relationship between RD50 values and human sensory irritation responses in a quantitative manner, particularly for chemicals that produce burning sensation of the eyes, nose, or throat, based on lowest observed adverse effect levels reported for human subjects.
GENE POLYMORPHISM | PM2.5 and Genetics of Oxidative Stress
Reduced defenses against oxidative stress due to GSTM1 deletion have been shown to modify the effects of PM2.5 (particulate matter < 2.5 µm in aerodynamic diameter) on heart rate variability (HRV) in a cross-sectional analysis of the Normative Aging Study. Chahine et al. (p. 1617) extended this to include a longitudinal analysis with more subjects, and they also examined the GT short tandem repeat polymorphism in the HMOX1 promoter. PM2.5 was significantly associated with SDNN (standard deviation of normal-to-normal intervals) and high frequency in all subjects. Data suggest that particle exposure interacts with individual variations in the antioxidant response pathway to determine its effects on HRV.
Also see Science Selections, p. A551
ENDOCRINE SYSTEM | PCB Metabolism and Thyroid Hormone Action
Polychlorinated biphenyls (PCBs) may interfere with thyroid hormone (TH) signaling by reducing TH levels in blood, by exerting direct effects on TH receptors (TRs), or both. Gauger et al. (p. 1623) identified individual PCBs that directly affect TH signaling by acting on the TR. PCB 126 induces CYP1A1 through the aryl hydrocarbon receptor in GH3 cells, and CYP1A1 activates PCB 105 and/or PCB 118 to a form that acts as a TR agonist. Data suggest that some tissues may be especially vulnerable to PCBs that interfere directly with TH signaling because of their capacity to express CYP1A1 in response to coplanar PCBs if sufficient mono-ortho PCBs are present.
NANOTECHNOLOGY | P25 Neurotoxicity
Titanium dioxide is a widely used nanomaterial whose photoreactivity suggests that it could damage biological targets (e.g., brain) through oxidative stress. Long et al. (p. 1631) exposed brain cultures of immortalized mouse microglia (BV2), rat dopaminergic neurons (N27), and primary cultures of embryonic rat striatum to Degussa P25, a commercially available TiO2 nanomaterial, and measured physical properties of P25 under conditions that paralleled biological measures. The data indicate that P25 stimulates reactive oxygen species (ROS) in BV2 microglia and is nontoxic to isolated N27 neurons. However, P25 at low concentrations rapidly damages neurons in complex brain cultures, plausibly though microglial-generated ROS.
RISK ASSESSMENT | Source-Specific Air Pollution Exposure
Although the dispersion model approach has been used in some epidemiologic studies to examine health effects of traffic-specific air pollution, no study has evaluated the model predictions vigorously. Liu et al. (p. 1638) evaluated total and traffic-specific PM10 (particulate matter with aerodynamic diameter < 10 µm), PM2.5, nitrogen dioxide, and NOx concentrations predicted by Gaussian dispersion models against fixed-site measurements at different locations including traffic-impacted, urban background, and alpine settings between and across cities. The model predictions were then used to estimate individual subjects' historical and cumulative exposures with a temporal trend model. The dispersion model predictions for PM10 are suitable for examining individual exposures and health effects within and between cities.
GENE EXPRESSION | BPA Modulates ER? Expression in Prostate Cancer
Androgen receptor (AR) activity is required for growth and progression of prostatic adenocarcinomas, and therapy for disseminated disease depends on ablation of AR activity. Recurrent tumors ultimately arise when AR has been reactivated. Hess-Wilson et al. (p. 1646) used microarray analysis to investigate the mechanism of action of bisphenol A (BPA) action in cancer cells carrying BPA-responsive AR mutants. BPA induces a distinct gene expression signature in prostate cancer cells expressing a somatic AR mutation, and a major molecular consequence of BPA action is down-regulation of estrogen receptor? (ER?). Because ER? antagonizes AR function and AR-dependent proliferation, these results reveal a novel mechanism by which BPA likely regulates cellular proliferation.
NANOTECHNOLOGY | Hazard Assessment for Nanoparticles
Balbus et al. (p. 1654) present the findings from a nanotoxicology workshop held 6–7 April 2006 in Washington, DC. Over 2 days, 26 scientists from government, academia, industry, and nonprofit organizations addressed two specific questions: What information is needed to understand the human health impact of engineered nanoparticles? And how is this information best obtained? To assess hazards of nanoparticles in the near-term, it was recommended that existing in vivo toxicologic tests should be used because of their greater familiarity and interpretability.
Environmental Medicine
CARDIOVASCULAR DISEASE | Noise Exposure and Ambulatory Vascular Properties
Epidemiologic studies have demonstrated that occupational noise exposure is associated with hypertension, but the related mechanism in vascular structural changes is unclear. Chang et al. (p. 1660) investigated effects of occupational noise exposure on ambulatory vascular structural properties in male workers. Volunteers were recruited and divided into a high-exposure group and a low-exposure group based on environmental noise measurement in an automobile manufacturing company. The findings suggest that occupational noise exposure may have sustained, not transient, effects on vascular properties of automobile workers, and that it enhances the development of hypertension.
Children's Health
ASTHMA | Home Pollutant Exposures in Inner-City Children
Evidence for environmental causes of asthma is limited, especially among African Americans. To look for systematic differences in early-life domestic exposures between inner-city preschool children with and without asthma, Diette et al. (p. 1665) performed a study of home indoor air pollutants and allergens. Exposures to common home indoor pollutants and allergens are similar for inner-city preschool children with and without asthma. Although these exposures may exacerbate existing asthma, this study does not support a causative role of these factors for risk of developing childhood asthma.
FETAL DEVELOPMENT | Polyfluoroalkyl Compounds and Fetal Growth
Recent studies have reported developmental toxicity among rodents dosed with perfluorooctane- sulfonate (PFOS) and perfluorooctanoate (PFOA). Apelberg et al. (p. 1670) examined the relationship between PFOS and PFOA cord serum concentrations (surrogates for in utero exposures) and gestational age, birth weight, and birth size in humans. The study involved a hospital-based cross-sectional epidemiologic study of singleton deliveries in Baltimore, Maryland. Despite relatively low cord serum concentrations, the authors observed small negative associations between both PFOS and PFOA concentrations and birth weight and size. Future studies should attempt to replicate these findings in other populations.
Also see Science Selections, p. A550
FETAL DEVELOPMENT | Perfluorinated Chemicals and Fetal Growth
Perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) are man-made, persistent organic pollutants widely spread in the environment and human populations. They have been found to interfere with fetal growth in some animal models, but whether a similar effect is seen in humans is uncertain. Fei et al. (p. 1677) investigated the association between plasma levels of PFOS and PFOA in pregnant women and their infants' birth weight and length of gestation. The nationwide cohort data suggest an inverse association between maternal plasma PFOA levels and birth weight. Because of widespread exposure to these chemicals, the findings may be a potential public health concern.
