Environews
FOCUS | Rooting Out Invasive Species: Lessons from Down Under
In Australia and New Zealand, where ecosystems have evolved largely in isolation, the threat posed by invasive exotic species can be especially potent. The response from officials in these two countries has been equally potent. This article (p. A352) takes a look at how Australia and New Zealand are implementing biosecurity measures to control the movement of invasive plant, animal, and insect species across their borders, and discusses how the experiences of these two nations may benefit public health managers in other countries.
INNOVATIONS | The Vanadium Advantage: Flow Batteries Put Wind Energy in the Bank
Renewable resources provide a host of energy-saving and environmental benefits. Wind power in particular is emerging as one of the world's fastest growing alternative fuels. But although this fuel offers numerous advantages, stockpiling it for large-capacity use at reasonable cost can be challenging. This article (p. A358) describes vanadium redox-flow batteries, a new way to store wind power stably.
Research
EXPOSURE ASSESSMENT | Spatial and Temporal Variation in PM2.5
Many studies have demonstrated links between particulate matter (PM) and adverse health effects, but the chemical components of the PM mixture that cause injury are unknown. Bell et al. (p. 989) describe the challenges of analyzing a national database of PM < 2.5 µm in aerodynamic diameter (PM2.5), identify important variable components of PM2.5, and characterize the seasonal and regional variability of targeted compounds. Further investigation of the subset of identified PM2.5 components is needed to determine whether their daily variation is associated with daily variation of health indicators, and whether their seasonal and regional patterns can explain the seasonal and regional heterogeneity in health risks caused by PM10 and PM2.5.
CARDIOVASCULAR DISEASE | Improved Stove Intervention Lowers Blood Pressure
RESPIRE, a randomized trial of an improved woodstove with a chimney (the plancha), was conducted in Guatemala to assess health effects of long-term reductions in wood smoke exposure. Given the evidence that ambient particles increase blood pressure, McCracken et al. (p. 996) hypothesized that use of the plancha would lower blood pressure. Two study designs were used: between-group comparisons based on randomized stove assignment, and before-and-after comparisons within subjects before and after they received the stoves. The between-group comparisons provide evidence, particularly for diastolic blood pressure, that use of the improved stove reduces blood pressure, and the before-and-after comparisons are consistent with this evidence.
CARDIOVASCULAR DISEASE | Obesity Modifies PM-Mediated Cardiac Effects
Increasing evidence suggests that obesity may increase susceptibility to adverse effects of air pollution. Particulate matter, especially PM2.5 (PM < 2.5 µm in aerodynamic diameter), is associated with increased cardiac events and reduction of heart rate variability (HRV). Chen et al. (p. 1002) examined PM2.5-mediated acute effects on HRV and heart rate (HR) using ten 24-hr and thirteen 48-hr ambulatory electrocardiogram recordings collected from 18 boilermakers (39.5 ± 9.1 years of age, mean ± SD) exposed to high-levels of metal particulates. The study revealed greater autonomic cardiac responses to metal particulates in obese workers (reduced HRV and increased HR), which supports the hypothesis that obesity may affect susceptibility to acute cardiovascular effects of fine particles.
RESPIRATORY DISEASE | Office Exposures and Adult-Onset Asthma
Office exposures, which have been linked to symptoms of sick building syndrome, are gaining importance because an increasing proportion of the workforce is working in office environments. Jaakkola and Jaakkola (p. 1007) assessed the relationship of exposure to carbonless copy paper, paper dust, and fumes from photocopiers and printers, to adult-onset asthma. The study provides new evidence that exposures to paper dust and carbonless copy paper in office work are related to increased risk of adult-onset asthma.
CARDIOVASCULAR DISEASE | Interactions of Ultrafine Carbon Black with Iron and Nickel on HRV
Particulate matter (PM)-associated alterations in heart rate variability (HRV) have been reported, but the results are inconsistent. Chang et al. (p. 1012) proposed that different components cause the discrepancy; therefore, they attempted to determine whether different exposure would cause different HRV effects, and to verify the interactions between coexposing components. PM components may induce different cardioregulatory responses, and a single component can induce different responses during different phases. Concurrent exposure to ultrafine carbon black and either iron or nickel might introduce interactions on cardioregulatory effects.
BONE AND CARTILAGE | Lead Exposure and Osteoporosis in Adults—NHANES III
Osteoporosis is a reduction in bone mass sufficient to increase the risk of fracture. Lead exposure during childhood may be a risk factor for low bone mineral density (BMD). Lead exposure is associated with a decrease in BMD in animals, but human studies are limited. Campbell and Auinger (p. 1018) used data from the Third National Health and Nutrition Examination Survey (NHANES III) to explore the association between lead exposure and osteoporosis in adults. They found a significant inverse association between lead exposure and BMD among white subjects. Because of the cross-sectional design of NHANES, the authors cannot make inferences about the temporal sequence of this association.
SKIN | Lack of Sensitization by Pfiesteria Extract
Members of the estuarine dinoflagellate genus Pfiesteria have been reported to be responsible for massive fish kills in the southeastern United States. Exposure to waters containing Pfiesteria blooms might result in Pfiesteria-induced dermal irritation and inflammation. Patterson et al. (p. 1023) examined a bioactive C18-bound putative toxin (CPE) extracted from Pfiesteria-ladenaquarium water to evaluate its potential to produce inflammation and dermal sensitization and to determine whether the inflammation and dermatitis reported in early human exposure studies were allergic or irritant in nature.
ENDOCRINE SYSTEM | Phthalates and Thyroid Hormones
Phthalates are used extensively in many personal-care and consumer products, resulting in widespread nonoccupational human exposure. A limited number of animal studies have suggested that exposure to phthalates may be associated with altered thyroid function, but human data are lacking. Meeker et al. (p. 1029) collectedconcurrent samples of urine and blood from 408 adult men and measured urinary concentrations of mono(2-ethylhexyl) phthalate (MEHP) and other phthalate monoester metabolites, along with serum levels of free thyroxine (T4), total triiodothyronine (T3), and thyroid-stimulating hormone. Urinary MEHP concentrations may be associated with altered free T4 and/or T3 levels in adult men, but additional study is needed to confirm their findings.
Also see Science Selections, p. A363
POPULATION HEALTH | Fluoroquinolone-Resistant Campylobacter Persists on Poultry Products
The use of antibiotics in food animal production has been associated with antibiotic-resistant infections in humans. In 2005, the Food and Drug Administration (FDA) banned fluoroquinolone use in U.S. poultry production in order to reduce the prevalence of fluoroquinolone-resistant Campylobacter. Price et al. (p. 1035) found no significant change in the proportion of fluoroquinolone-resistant Campylobacter isolates from two conventional producers over the study period, and Campylobacter strains from the two conventional producers were significantly more likely to be fluoroquinolone resistant than those from antibiotic-free producers. The results of this study indicate that fluoroquinolone-resistant Campylobacter may be persistent contaminants of poultry products even after on-farm fluoroquinolone use has ceased.
Also see Science Selections, p. A362
POPULATION HEALTH | Resistant Enterococci in Surface and Groundwater
The nontherapeutic use of antibiotics in swine feed can select for antibiotic resistance in swine enteric bacteria. Leaking swine waste storage pits and the land application of swine manure can result in the dispersion of resistant bacteria to water sources. Sapkota et al. (p. 1040) detected elevated levels of fecal indicators and antibiotic-resistant enterococci in surface water and groundwater situated down gradient from a swine facility compared with up-gradient sources. These findings provide additional evidence that water contaminated with swine manure could contribute to the spread of antibiotic resistance.
CARDIOVASCULAR DISEASE | Night HRV and Occupational PM
Although studies have documented the association between heart rate variability (HRV) and ambient particulate exposures, the association between HRV, especially at night, and metal-rich, occupational particulate exposures remains unclear. Cavallari et al. (p. 1046) used 24-hr ambulatory electrocardiograms to monitor 36 male boilermaker welders (mean age of 41 years) over a workday and nonworkday to investigate the association between long-duration HRV and occupational exposures to particulate matter < 2.5 µm in aerodynamic diameter (PM2.5). The metal-rich particulate exposures were associated with decreased long-duration HRV, especially at night. Further research is needed to elucidate which particulate metal constituent is responsible for decreased HRV.
METABOLISM | PBDE Metabolites in Mice
Previous studies have shown that polybrominated diphenyl ethers (PBDEs) behave as weak estrogens in animal and in cell culture bioassays. In vivo metabolites of PBDEs are suspected to cause these effects. Qiu et al. (p. 1052) analyzed mouse plasma samples collected after continuous exposure of mice to DE-71, a commercial pentabromodiphenyl ether product. They found three metabolic pathways: cleavage of the diphenyl ether bond, which formed bromophenols, and both hydroxylation and debromination/hydroxylation, which formed hydroxylated (HO)-BDEs. para-HO-PBDEs are most likely formed from 2,2´,4,4´-tetrabromodiphenyl ether (BDE-47); these metabolites could be the most thyroxine-like and/or estrogen-like congeners among the HO-PBDEs.
ENVIRONMENTAL TOXICOLOGY | C60 and Toxicity of THF Decomposition Products
C60, a highly insoluble nanoparticle, can form colloidal suspended aggregates in water, which may lead to environmental exposure in aquatic organisms. Toxicity from C60 aggregates has been reported; however, the effects could be caused by tetrahydrofuran (THF), a vehicle used to prepare the aggregates. Henry et al. (p. 1059) investigated changes in survival and gene expression in larval zebrafish, Danio rerio, after exposure to aggregates of C60 dissolved in either water or THF. This research is the first to link directly the toxic effects to a THF degradation product (-butyrolactone) rather than to C60 and may explain toxicity attributed to C60 in other investigations.
RISK ASSESSMENT | Environmental Asbestos Exposure and Mesothelioma Risk
Environmental asbestos pollution can cause malignant mesothelioma, but few studies have involved dose–response analyses with detailed information on occupational, domestic, and environmental exposures. In this case–control study, Maule et al. (p. 1066) examined the spatial variation of mesothelioma risk in an area with high levels of asbestos pollution from an asbestos cement plant in Casale Monferrato, Italy, adjusting for occupational and domestic exposures. This study provides strong evidence that asbestos pollution from an industrial source greatly increases mesothelioma risk. Furthermore, relative risks from occupational exposure were were markedly increased after adjusting for residential distance.
CARDIOVASCULAR DISEASE | Air Pollution and Inflammation
Ambient air pollution has been associated with cardiovascular disease exacerbation. Rückerl et al. (p. 1072) conducted a prospective longitudinal study of 1,003 myocardial infarction (MI) survivors in six European cities to determine whether particulate air pollution induced systemic inflammation and contributed to increased vulnerability to elevated concentrations of ambient particles. The results indicate an immediate response of interleukin-6 to ambient air pollution, which might lead to the production of acute-phase proteins, as indicated by increased fibrinogen levels. This could provide a link between air pollution and adverse cardiac events.
Also see Science Selections, p. A362
METABOLISM | Metabolism of Low-Dose Inorganic Arsenic in Europe
The wide variation in susceptibility to health effects of arsenic may be due to differences in arsenic metabolism (arsenic is metabolized by reduction and methylation reactions, catalyzed by reductases and methyltransferases). Lindberg et al. (p. 1081) measuredarsenic metabolites in urine from a group of 415 individuals from Hungary, Romania, and Slovakia. The factors investigated (gene polymorphisms, body mass index, and sex) explained almost 20% of the variation seen in the metabolism of arsenic among men and only around 4% among women. The rest of the variation is probably explained by other methyltransferases backing up the methylation of arsenic.
ENVIRONMENTAL JUSTICE | Superfund: Evaluating the Impact of Executive Order 12898
Hazardous waste sites that are perceived to be a significant threat to both surrounding populations and the environment can be placed on the U.S. Environmental Protection Agency's Superfund list and qualify for federal cleanup funds. However, the representation of minority and low-income populations in this cleanup program is lower than would be expected. In 1994, President Clinton signed Executive Order 12898requiring that federal agencies implement environmental justice policies to specifically address the disproportionate environmental effects of federal programs and policies on minority and low-income populations. O'Neil (p. 1087) suggests that despite environmental justice legislation, sites in minority and poor areas discovered since the 1994 executive order are even less likely to be listed as Superfund sites.
CARCINOGENESIS | Cadmium-Induced Apoptotic Resistance
Cadmium induces malignant transformation of the human prostate epithelial cell line, and these cadmium-transformed prostate epithelial (CTPE) cells acquire apoptotic resistance concurrently with malignant phenotype. Qu et al. (p. 1094) investigated the mechanism of acquired apoptotic resistance in CTPE cells. Compared with the control, CTPE cells showed a generalized resistance to apoptosis induced by cadmium, cisplatin, or etoposide. Disruption of the JNK pathway and Bcl-2 overexpression play important roles in CTPE cells' resistance to apoptosis during malignant transformation. Bcl-2 BH4 domain is required for modulating JNK phosphorylation and antiapoptotic function.
BIOMONITORS | Metallothionein as a Biomarker for Arsenicosis
Metallothionein (MT), a metal-binding protein that protects against metal intoxication, could be a biomarker for individual sensitivity to metal toxicity. Liu et al. (p. 1101) assessed the use of bloodborne MT transcript as a reflection of tissue MT levels and examined the potential role of MT in arsenic toxicity in an environmentally exposed human population. Blood MT transcript appears to be a useful biomarker of tissue MT levels. Arsenicosis patients in Guizhou, China, have significantly lower MT transcript levels in blood, which may have predisposed this population to arsenic intoxication.
Children's Health
RISK CHARACTERIZATION | Water Manganese Exposure and Infant Mortality
Manganese is a common natural contaminant of groundwater in Bangladesh. Hafeman et al. (p. 1107) assessed the association between water manganese and all-cause infant mortality in the offspring of female participants in the Health Effects of Arsenic Longitudinal Study Cohort. Infants exposed to water manganese ≥ 0.4 mg/L (the 2003 World Health Organization standard) had an elevated mortality risk during the first year of life compared with unexposed infants. The findings indicate a possible association between manganese exposure and infant mortality. However, given the methodologic limitations of the study, the association needs to be confirmed through future work.
Also see Science Selections, p. A363
RISK CHARACTERIZATION | Children Blood Lead in an e-Waste Recycling Town
Huo et al.(p. 1113) compared the blood lead levels (BLLs) of children living in the electronic-waste (e-waste) recycling town of Guiyu, China, with those of children living in the neighboring town of Chendian. Statistical analyses showed that children living in Guiyu have a significantly higher BLL compared with those living in Chendian; 88% of children in Guiyu had BLLs > 10 µg/dL compared with 37.7% of children in Chendian. In addition, a significant increasing trend in BLLs was observed with increasing age in Guiyu. The BLLs in children appear to be correlated with the number of e-waste workshops.
FETAL DEVELOPMENT | Air Pollution and Low Birth Weight
Several studies have examined whether air pollution affects birth weight; however, results vary and many studies were focused on Southern California or were conducted outside of the United States. Bell et al. (p. 1118) investigated maternal exposure to particulate matter with aerodynamic diameter < 10 µm (PM10) or < 2.5 µm (PM2.5), sulfur dioxide, nitrogen dioxide, and carbon monoxide and birth weight for 358,504 births in Massachusetts and Connecticut during 1999–2002.The results indicate that exposure to air pollution, even at low levels, may increase the risk of low birth weight, particularly for some segments of the population.