Environews
NIEHS NEWS | IOM: The Economics of Better Environmental Health
Over the years, epidemiological studies have linked air pollution exposure to a range of respiratory illnesses such as asthma, but less is known about how to translate health effects into economic values. The first of two NIEHS News articles (p. A80) looks at ideas on this topic generated and discussed at the Institute of Medicine’s recent Roundtable on Environmental Health Sciences, Research, and Medicine. In other news, a recent conference highlights advances in toxicogenomics made possible by the Toxicogenomics Research Consortium and the National Center for Toxicogenomics.
FOCUS | Biodiesel: Cultivating Alternative Fuels
With fossil fuel supplies diminishing and becoming ever costlier, the need for alternative fuels is becoming more pressing. One up-and-coming solution can be traced back as far as the 1800s: biodiesel. This article (p. A86) explores why interest in biodiesel continues to grow, the benefits of its use, and the impacts this fuel may have on the environment.
SPHERES OF INFLUENCE | Battle of the Biofuels
With skyrocketing petroleum prices and war in the oil-producing nations of the Middle East, biofuels are increasingly touted as desirable alternatives to petroleum fuels. How do biofuels compete with conventional fuels and each other on a cost and environmental basis? This article (p. A92) discusses the results of a recent study comparing corn grain ethanol and soybean biodiesel.
Research
REMEDIATION | Soil Contamination from PCB-Containing Buildings
Polychlorinated biphenyls (PCBs) in construction materials, such as caulking and expansion joints, may constitute a source of contamination in building interiors and in surrounding soil. Studies of soil contamination have been conducted around buildings where the caulking has been removed by grinding or scraping. These PCBs in soil may have been generated during removal of the caulking, but natural weathering and deterioration of caulking may also be a source. Herrick et al. (p. 173) measured PCB levels in soil surrounding buildings where PCB-containing caulk was still in place and evaluated the mobility of the PCBs from caulking using the Toxicity Characteristic Leaching Procedure.
BIOMARKERS | Air Pollution, Smoking, and Homocysteine
Mild hyperhomocysteinemia is independently associated with an increased risk of cardiovascular disease. Air pollution exposure induces short-term inflammatory changes that may determine hyperhomocysteinemia, particularly in the presence of a preexisting proinflammatory status, such as that found in cigarette smokers. Baccarelli et al. (p. 176) examined the relation of air pollution levels with fasting and postmethionine-load total homocysteine (tHcy) in 1,213 normal subjects from Lombardia, Italy. In smokers, 24-hr PM10 (particulate matter < 10 µm in aerodynamic diameter) levels were associated with increases in fasting and postmethionine-load tHcy, respectively, but no association was seen in nonsmokers. Air particles may interact with cigarette smoking and increase plasma homocysteine in healthy subjects.
HUMAN TOXICOLOGY | Temporal Patterns in Perchlorate, Thiocyanate, and Iodide Excretion
in Human Milk
Perchlorate (a common contaminant of water, food, and human milk) and thiocyanate interfere with iodide uptake at the sodium–iodide symporter and are potential disruptors of thyroid hormone synthesis. Although it is known that iodide undergoes significant diurnal variations in serum and urinary excretion, less is known about diurnal variations of milk iodide levels. Kirk et al. (p. 182) investigated the variability of perchlorate, thiocyanate, and iodide in serially collected samples of human milk.
NANOTOXICOLOGY | Particle Parameters Relevant for Lung Inflammation
Little is known about the mechanisms involved in lung inflammation caused by the inhalation or instillation of nanoparticles. Current research is focused on identifying the particle parameter that can serve as a proper dose metric. Wittmaack (p. 187) reviewed the published dose–response data on acute lung inflammation after instillation of titanium dioxide particles or six types of carbon nanoparticles. The analysis suggests that the physical characterization of nanoparticles and the methods to determine surface toxicity must be improved significantly before the appropriate dose metric for lung inflammation can be safely identified. Refinements are also needed in quantifying response to exposure.
INFECTIOUS DISEASE | Wind Direction and Vibrio cholerae Dissemination
The relevance of climatic events as causative factors for cholera epidemics is well known; however, few studies have investigated the involvement of climatic factors in intracontinental disease distribution. To determine whether the spreading of cholera epidemics is related to the dominant wind direction over land, Paz and Broza (p. 195) examined the geographic diffusion of three cholera outbreaks. Their results support the hypothesis that aeroplankton carry the cholera bacteria from one body of water to an adjacent one.
NEUROBEHAVIORAL DISEASE | Benefits and Potential Risks of Succimer Lead Chelation
There is growing pressure for clinicians to prescribe chelation therapy when blood lead levels are only slightly elevated. However, very few studies have evaluated whether chelation improves cognitive outcomes in Pb-exposed children, or whether these agents have adverse effects that may affect brain development in the absence of Pb exposure. Stangle et al. (p. 201) show that treatment with any chelating agent can alleviate cognitive deficits due to Pb exposure. The findings suggest that it may be possible to identify a succimer treatment protocol that improves cognitive outcomes in Pb-exposed children.
Also see Science Selections, p. A97
ASTHMA | Human Exposure to Formaldehyde
Exposure to formaldehyde may lead to exacerbation of asthma. Ezratty et al. (p. 210) investigated whether exposure to a low level of formaldehyde enhances inhaled allergen responses. Formaldehyde exposure did not increase allergen-induced responsiveness to methacholine. The authors found no formaldehyde-associated effect on the airway inflammatory response, in particular the eosinophilic inflammatory response, which was induced by the allergen challenge 8 hr earlier. Exposure to formaldehyde had no significant deleterious effect on airway allergen responsiveness of patients with intermittent asthma; in fact, a trend toward a protective effect was found.
ASTHMA | Dust Weight and Asthma Prevalence
Settled dust has been used to assess exposures to allergens and other biologically active components, but it has not been considered in the aggregate in relation to respiratory health outcomes in the general population. Elliott et al. (p. 215) addressed whether total house dust weight, an index of total dust exposure, was associated with respiratory health outcomes in the National Survey of Lead and Allergens in Housing (1998–1999). Dust weight, an index of total dust exposure in the home, may contribute to respiratory outcomes independently of the exposure to specific components.
EXPOSURE ASSESSMENT | Chloramines and Blood Lead Levels
More municipal water treatment plants are using chloramines as a disinfectant in order to reduce carcinogenic by-products. In some instances, this has coincided with an increase in lead levels in drinking water in those systems. Lead in drinking water can be a significant health risk. Using data from Wayne County, North Carolina, Miranda et al. (p. 221) tested the potential effect of water treatment systems switching to chloramines for disinfection on childhood blood lead levels. Their results indicate that changing to chloramine disinfection may lead to an increase in blood lead levels, the impact of which is progressively mitigated in newer housing.
Also see Science Selections, p. A96
EXPOSURE ASSESSMENT | Exposure to Perfluorinated Chemicals through Lactation
Only limited data exist on lactation as an exposure source of persistent perfluorinated chemicals (PFCs) for children. Kärrman et al. (p. 226) studied occurrence and levels of PFCs in human milk in relation to maternal serum together with the temporal trend in milk levels between 1996 and 2004 in Sweden. They detected eight PFCs in the serum samples; five of them were also above the detection limits in the milk samples. The calculated total amount of PFCs transferred by lactation to a breast-fed infant was approximately 200 ng/day. Lactation is a considerable source of exposure for infants, and reference concentrations for hazard assessments are needed.
Also see Science Selections, p. A97
RISK ASSESSMENT | A Polygenic Approach to Assess Risk
Incorporating the influence of genetic variation in the risk assessment process is often considered, but no generalized approach exists. Many human diseases are complex in nature, and are influenced variably by environmental, physiologic, and genetic factors. The genetic components most responsible for differences in individual disease risk are thought to be DNA variants (polymorphisms) that influence the expression or function of mediators involved in the pathological processes. Demchuk et al. (p. 231) estimated the combinatorial contribution of multiple genetic variants to disease risk. They predict that multiple disease variants broaden the risk distribution, facilitating the identification of susceptible populations.
EXPOSURE ASSESSMENT | Mercury Exposure from Estuarine and Marine Fish
Methylmercury exposure causes a variety of adverse effects on human health. Per capita estimates of mercury exposure are critical for risk assessments and for developing effective risk management strategies. Sunderland (p. 235) investigated the impact of natural stochasticity in mercury concentrations among fish and shellfish harvested from the Atlantic Ocean, the Pacific Ocean, and foreign shores on estimated mercury exposures. Differences in reported mercury concentrations can significantly affect per capita mercury intake estimates, pointing to the importance of spatially refined mercury concentration data. The analysis shows that national exposure estimates are most influenced by reported concentrations in imported tuna, swordfish, and shrimp; Pacific pollock; and Atlantic crabs.
CARCINOGENESIS | Arsenic-Induced Androgen Independence
Prostate cancer progression often occurs with overexpression of growth factors and receptors, many of which engage the Ras/mitogen-activated protein kinase (MAPK) pathway. Benbrahim-Tallaa et al. (p. 243) used arsenic-transformed human prostate epithelial cells, which show androgen-independent growth, to study the possibility that chronic activation of Ras/MAPK signaling may contribute to arsenic-induced prostate cancer progression. Chronic activation of this pathway can sensitize the androgen receptor to subphysiologic levels of androgen. This may be important in arsenic carcinogenesis and provide a mechanism for prostate cancer progression driven by diverse agents.
EXPOSURE ASSESSMENT | Pesticide–Exposure Matrix
In retrospective studies of the health effects of home and garden pesticides, self-reported information typically forms the basis for exposure assessment. Participants generally find it easier to remember the types of pests treated than the specific pesticides used. However, if the goal of the study is to assess disease risk from specific chemicals, the investigator must be able to link the pest type treated with specific chemicals or products. Colt et al. (p. 248) developed a "pesticide– exposure matrix" that lists active ingredients on the market for treating different types of pests in past years, and provide an estimate of the probability that each active ingredient was used.
EXPOSURE ASSESSMENT | Bioaccumulation Data Sources
Chemical management programs strive to protect human health and the environment by accurately identifying persistent, bioaccumulative, toxic substances and restricting their use in commerce. The advance of these programs is challenged by the reality that few empirical data are available for the tens of thousands of commercial substances that require evaluation. In 2005, a workshop was held for experts from governments, industry, and academia to examine the availability and quality of in vivo fish bioconcentration and bioaccumulation data, and to propose steps to improve its prediction. Weisbrod et al. (p. 255) reviewed the quantity, features, and public availability of bioconcentration, bioaccumulation, and biota–sediment accumulation data.
Environmental Medicine
RESPIRATORY DISEASE | Hypersensitivity Pneumonitis from Hot Water Aerosol
Human activities associated with aerosol-generating hot water sources are increasingly popular. Recently, a hypersensitivity pneumonitis (HP)-like granulomatous lung disease, with nontuberculous mycobacteria from exposure to hot water aerosols from hot tubs/spas, showers, and indoor swimming pools (also called "hot tub lung"), has been described in immunocompetent individuals. Sood et al. (p. 262) examined four additional cases of hot tub lung and compared these cases with others reported in the literature. Primary prevention of this disease relies on ventilation and good use practices. Secondary prevention of this disease requires education of both the general public and clinicians to allow for the early diagnosis of the disease.
RISK CHARACTERIZATION | Illness Outbreaks Associated with Swimming Pools
Chlorination destroys pathogens in swimming pool water, but by-products of chlorination can cause human illness. Bowen et al. (p. 267) investigated outbreaks of ocular and respiratory symptoms associated with chlorinated indoor swimming pools at two hotels. The authors interviewed registered guests and companions who stayed at hotels X and Y within 2 days of outbreak onset. Indoor pool areas were associated with illness in these outbreaks. A large proportion of bathers were affected; symptoms were consistent with chloramine exposure and were sometimes severe. Improved staff training, pool maintenance, and pool area ventilation could prevent future outbreaks.
Children's Health
FETAL DEVELOPMENT | Cryptorchidism and Maternal Alcohol Consumption
Damgaard et al. (p. 272) investigated the association between maternal alcohol consumption during pregnancy and cryptorchidism (undescended testis) among newborn boys. The odds for cryptorchidism increased with increasing weekly alcohol consumption. After adjustment for confounders (country, smoking, caffeine intake, binge episodes, social class, maternal age, parity, maturity, and birth weight), the odds remained significant for women with a weekly consumption of five or more alcoholic drinks. Regular alcohol intake during pregnancy appears to increase the risk of congenital cryptorchidism in boys. Therefore, counseling of pregnant women with regard to alcohol consumption should take into account this new finding.
Also see Science Selections, p. A96
EXPOSURE ASSESSMENT | A Comparison of Land Use Regression Models
Ryan et al. (p. 278) previously reported an association between infant wheezing and residence < 100 m from stop-and-go bus and truck traffic. The use of a proximity model, however, may lead to exposure misclassification. The authors compared results obtained from a land use regression (LUR) model of exposure to truck and bus traffic with those obtained with a proximity model. The estimates derived from the LUR model were then related to infant wheezing. The LUR model resulted in a range of elemental carbon attributable to traffic individually derived for all infants' homes that may reduce the exposure misclassification that can arise from a proximity model.
NEURODEVELOPMENT | Arsenic Exposure and Intellectual Function
Wasserman et al. (p. 285) recently reported results of an investigation of intellectual function in 10-year-old children in Bangladesh who had been exposed to arsenic in drinking water from their home wells. The authors present results of a similar investigation of randomly selected 6-year-olds whose parents participated in the prospective study of the health effects of As exposure in residents of Araihazar, Bangladesh. Exposure to As from drinking water was associated with reduced intellectual function before and after adjusting for water manganese, blood lead, and sociodemographic features known to contribute to intellectual function. This expands concerns about As neurotoxicity to a younger age group.
FETAL DEVELOPMENT | Disinfection By-Products and Preterm Births
Using improved exposure assessment and more appropriate analysis methods than used in prior studies, Lewis et al. (p. 290) evaluated the association between drinking-water disinfection by-products and preterm births. During 1999–2001, vital record data were obtained for a large, racially diverse population residing in 27 Massachusetts communities that received drinking water from a single public utility. The findings confirm previous reports of a negative association of delivering preterm during the second trimester. The data also suggest a possible positive association with shorter-term third trimester total trihalomethane exposure in mothers of lower socioeconomic status.
Mini-Monograph
HEALTH POLICY | Environmental Health Impacts of CAFOs
A scientific conference that brought together environmental scientists from North America and Europe addressed major environmental health issues associated with concentrated animal feeding operations (CAFOs) in large, industrialized livestock production facilities. The Mini-Monograph (p. 296) outlines the state of the science and public health concerns relating to livestock production, identifies areas in which further research is needed, suggests opportunities to translate science to policy initiatives that would effect improvements in public and environmental health, and outlines viable solutions to some of the current environmental health problems associated with CAFOs. In addition, several major concerns are discussed, including air and water contamination, the rise of antibiotic-resistant bacteria in livestock, and the specter of influenza outbreaks arising from industrialized poultry and swine production facilities located in proximity to each other and to humans.
