Environews
FOCUS | A Spreading Concern: Inhalational Health Effects of Mold
Mold growth brings with it more than just the nuisance of an unsightly appearance. Health effects of ingesting mycotoxins and dermatological fungal infections have long been known. Emerging research now suggests that mold also poses an inhalational health threat, especially for highly susceptible individuals with compromised immune systems. Even so, some experts say that health threats to less susceptible populations have been exaggerated. This article (p. A300) discusses some of the latest information regarding the potential health effects of mold exposure.
SPHERES OF INFLUENCE | Growing Green Roofs, One City at a Time
The versatile green roof—vegetation planted in soil atop a roof—is being shown to help ameliorate a number of city planner problems, from stormwater runoff to consumer energy consumption. Now some city governments are actively encouraging the installation of green roofs atop city buildings. Advocates say green roofs offer a range of environmental benefits to city dwellers, and new incentives are making it easier to install these rooftop gardens. This article (p. A306) takes a look at options being explored by cities across the United States for growing green roofs.
Review
RISK ASSESSMENT | Monetized Impact from Mercury Emissions
The U.S. Environmental Protection Agency has reported that the upper bound of benefits from removing mercury emissions by U.S. power plants after implementation of the Clean Air Interstate Rule (CAIR) is $210 million/year. In contrast, other studies have estimated that U.S. power plants impose an economic cost of $1.3 billion due to mercury emissions. Although it is impossible to directly compare these two estimates, Griffiths et al. (p. 841) compared the assumptions used and how they affect the results.
EXPOSURE ASSESSMENT | Indoor Air Pollution and Solid Fuels in China
Nearly all of China's rural residents and a decreasing fraction of urban residents use solid fuels (biomass and coal) for household cooking and/or heating. Global meta-analyses of epidemiologic studies indicate that indoor air pollution from solid fuel use in China is responsible for approximately 420,000 premature deaths annually, more than the approximately 300,000 attributed to urban outdoor air pollution in the country. To help elucidate the extent of this health hazard, Zhang and Smith (p. 848) reviewed some 200 publications in both Chinese and English language journals that reported health effects, exposure characteristics, and fuel/stove intervention options.
Research
EXPOSURE ASSESSMENT | Contaminated Groundwater and Waterborne Disease
A groundwater-associated gastrointestinal outbreak affected residents and visitors of South Bass Island, Ohio, between July and September 2004. Fong et al. (p. 856) examined the microbiological quality of groundwater wells on South Bass Island that provided potable water to public water systems, and they used hydrodynamics to explore the surface water–groundwater interactions of Lake Erie. Massive groundwater contamination on the island was likely caused by transport of microbiological contaminants from sewage discharges to the lake and from wastewater treatment facilities and septic tanks to the subsurface after extreme precipitation events. This may have raised the water table, saturated the subsurface, and—along with very strong Lake Erie currents on 24 July—forced a surge in water levels and rapid surface water–groundwater interchange throughout the island.
NEURODEVELOPMENT | Flame Retardants Reduce Synaptic Plasticity
Increasing environmental levels of brominated flame retardants raise concern about possible adverse effects, particularly through early developmental exposure. Dingemans et al. (p. 865) investigated neurodevelopmental mechanisms underlying behavioral impairments observed after neonatal exposure to polybrominated diphenyl ethers (PBDEs). Effects on synaptic plasticity, levels of postsynaptic proteins involved in long-term potentiation (LTP), and vesicular release mechanisms were studied ex vivo. The authors concluded that early neonatal exposure to a single high dose of BDE-47 causes a reduction of LTP, together with changes in postsynaptic proteins involved in synaptic plasticity in the mouse hippocampus.
CARDIOVASCULAR DISEASE | Lead and IHD
Lead exposure has been associated with higher blood pressure, hypertension, electrocardiogram abnormalities, and increased mortality from circulatory causes. Jain et al. (p. 871) assessed the association between bone lead (a more accurate biomarker of chronic lead exposure than blood lead) and risk for future ischemic heart disease (IHD). The authors studied a group of men in a prospective cohort study (VA Normative Aging Study) who underwent blood or bone lead measurements at baseline and were followed up for an IHD event. Men with increased blood and bone lead levels were at increased risk for future IHD. Although, the pathogenesis of IHD is multifactorial, lead exposure may be one of the risk factors.
ENDOCRINE SYSTEM | Phthalates, Waist Circumference, and Insulin Resistance
Phthalates impair rodent testicular function and have been associated with antiandrogenic effects in humans, including decreased testosterone levels. Low testosterone in adult human males has been associated with increased prevalence of obesity, insulin resistance, and diabetes. Stahlhut et al. (p. 876) investigated phthalate exposure and its associations with abdominal obesity and insulin resistance. In this cross-section of U.S. men, concentrations of several prevalent phthalate metabolites showed statistically significant correlations with abdominal obesity and insulin resistance. If confirmed by longitudinal studies, the findings would suggest that exposure to these phthalates may contribute to the population burden of obesity, insulin resistance, and related clinical disorders.
Also see Science Selections, p. A312
BONE AND CARTILAGE | PCBs, Organochlorine Pesticides, and Rheumatoid Arthritis
Persistent organic pollutants (POPs) can influence the immune system, possibly increasing the risk of rheumatoid arthritis (RA). Also, because metabolic change due to obesity has been proposed as one mechanism of osteoarthritis (OA), POPs stored in adipose tissue may be also associated with OA. Lee et al. (p. 883) examined associations of background exposure to POPs with arthritis among the general population. Among several POPs, dioxin-like polychlorinated biphenyls (PCBs) or nondioxin-like PCBs were positively associated with arthritis in women. Organochlorine pesticides were also weakly associated with the arthritis in women.
EXPOSURE ASSESSMENT | Dietary Arsenic Exposure
Millions of people in Bangladesh are at risk of chronic arsenic toxicity from drinking contaminated groundwater, but little is known about diet as an additional source of arsenic exposure. Kile et al. (p. 889) used a duplicate diet survey to quantify daily arsenic intake in 47 women in Pabna, Bangladesh. When drinking water concentrations exceeded the Bangladesh drinking water standard, ingested water was the dominant source of exposure. However, as drinking water arsenic concentrations decrease, the relative contribution of dietary arsenic sources to ingested dose becomes more important. The combined intake from both diet and drinking water can cause some individuals to exceed the provisional tolerable daily intake.
EXPOSURE ASSESSMENT | PBTK Model of Human Exposure to Naphthalene
Although dermal and inhalation exposure to JP-8 jet fuel have been measured in a few occupational exposure studies, a quantitative understanding of the relationship between external exposures and end-exhaled air concentrations has not been described for occupational and environmental exposure scenarios. Kim et al. (p. 894) constructed a physiologically based toxicokinetic (PBTK) model to quantify the relative contribution of dermal and inhalation exposures to the end-exhaled air concentrations of naphthalene among U.S. Air Force personnel. PBTK modeling allowed contributions of the end-exhaled air concentration of naphthalene to be partitioned between dermal and inhalation routes of exposure.
GENE EXPRESSION | 17β-Estradiol and BPA Induce Ar and Esr1 in Fetal Prostate
Hormonal alterations during development have lifelong effects on the prostate gland. Endogenous estrogens (e.g., 17β-estradiol) and synthetic estrogenic endocrine disruptors (e.g., bisphenol A) have similar effects on prostate development. Increasing exposure to estrogens in the low-dose, physiologic range results in permanent increases in the size and androgen responsiveness of the prostate, whereas exposure in the high-dose, pharmacologic range has the opposite effects. Richter et al. (p. 902) tested the hypothesis that the low-dose effects of estrogens on the developing prostate are associated with increased expression of androgen receptor and estrogen receptor 1 (α) genes in mesenchyme cells.
NEURODEVELOPMENT | Organophosphate Effects on Developing Brain FGFs
The fibroblast growth factor (FGF) superfamily of neurotrophic factors plays critical roles in neural cell development, brain assembly, and recovery from neuronal injury. Slotkin et al. (p. 909) administered two organophosphate pesticides, chlorpyrifos and diazinon, to neonatal rats using doses below the threshold for systemic toxicity or growth impairment, and spanning the threshold for barely detectable cholinesterase inhibition. The authors found similarities but also notable disparities in the responses to chlorpyrifos and diazinon; robust effects were observed even at doses that do not inhibit cholinesterase. These results support the idea that organophosphates differ in their propensity to elicit developmental neurotoxicity, unrelated to their anticholinesterase activity.
POPULATION HEALTH | Effectiveness of Arsenic Mitigation
An effective mitigation program for arsenic exposure from drinking water is needed in Bangladesh. Chen et al. (p. 917) measured changes in urinary As levels and used interviews to evaluate the effectiveness of a multifaceted mitigation program to reduce As exposure among individuals participating in a prospective cohort study initiated in 2000 in Araihazar, Bangladesh. The study shows that testing of wells and informing households of the consequences of As exposure, combined with installation of deep community wells where most needed, can effectively address the continuing public health emergency from arsenic in drinking water in Bangladesh.
NEURODEVELOPMENT | In Vitro Methods for Developmental Neurotoxicity Testing
Coecke et al. (p. 924) summarize the discussions, recommendations, and priorities of the first workshop on Incorporating In Vitro Alternative Methods for Developmental Neurotoxicity (DNT) Testing into International Hazard and Risk Assessment Strategies. The primary aim of the workshop was to identify and catalog potential methods that could be used to assess how data from in vitro alternative methods could help to predict and identify DNT hazards. Working groups focused on two different aspects: a) details on the science available in the field of DNT, and b) policy and strategy aspects to assess the integration of alternative methods in a regulatory framework.
Environmental Medicine
RESPIRATORY DISEASE | Silicatosis in a Carpet Installer
Szeinuk and Wilk-Rivard (p. 932) present the case of a carpet installer who was diagnosed with silicatosis, a form of pneumoconiosis. The patient had worked as a carpet installer for 15 years, and he was exposed to talc in the course of his work. The authors review different causes of silicatosis and discuss chronic exposure during carpet installation and the development of pneumoconiosis. They also review the relevance of mycobacterial infection in cases of silicosis and silicatosis.
Children's Health
MUTAGENESIS | Methylphenidate: Cytogenetic Effects in Children?
Attention deficit hyperactivity disorder (ADHD) is the most common psychiatric disorder in children and adolescents (6–12% affected). In the United States, treatment of ADHD with methylphenidate (MPH) has increased to a current prescription rate of > 5 million/year. However, there is concern about potential carcinogenic effects of MPH. Walitza et al. (p. 936) analyzed genomic damage in children with ADHD before and after initiation of MPH therapy and in children receiving chronic MPH therapy. The authors provide new information concerning the cytogenetic effect of MPH in children.
Also see Science Selections, p. A313
FETAL DEVELOPMENT | Declines in Sex Ratio at Birth in Japan and the United States
Davis et al. (p. 941) describe trends in sex ratio at birth and in fetal deaths in the United States (in African Americans and in whites) and in Japan, two industrial countries with well-characterized health data infrastructures, and they discuss possible explanations. Sex ratio declines are equivalent to a shift from male to female births of 135,000 white males in the United States and 127,000 males in Japan. Known and hypothesized risk factors for reduced sex ratio at birth and in fetal deaths cannot account fully for recent trends or racial or national differences.
Also see Science Selections, p. A312
EPIDEMIOLOGY | Childhood Leukemia in the Elbmarsch, Germany
During 1990–1991 a childhood leukemia cluster was observed in the sparsely populated region surrounding two nuclear establishments southeast of Hamburg, Germany, and several new cases have been reported since then. Hoffmann et al. (p. 947) ascertained all incident cases (< 15 years of age) during 1990–2005 within a 5-km radius of the Krümmel nuclear power plant. The incidence in this region is significantly higher than the childhood leukemia incidence for Germany as a whole. To date, no unique hazards have been identified in this population.
Also see Science Selections, p. A313
Mini-Monograph
BUILT ENVIRONMENT | Improving Indoor Environmental Quality
Indoor environmental contaminants are significant public health risks, particularly among children and the poor, and the societal costs of illnesses related to indoor environments are considerable. The Mini-Monograph (p. 953) reviews health risks associated with indoor environments, advances in source characterization, healthy building design, and intervention methods (especially childhood asthma). U.S. and European policy are also discussed.
