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Environmental Factor, March 2012

Extramural papers of the month

By Nancy Lamontagne

Obesity and childhood phthalate exposure

NIEHS grantees have published research that shows an association between obesity and childhood exposure to phthalates. These man-made endocrine disruptors are commonly used in plastic flooring and wall coverings, food processing materials, medical devices, and personal care products.

The researchers measured phthalate concentrations in the urine of 387 African-American and Hispanic children in New York City who were between 6 and 8 years old when enrolled in the study. One year later they measured the children’s body size characteristics, including body mass index (BMI), height, and waist circumference. The urine test showed that more than 97 percent of study participants had been exposed to phthalates. The researchers found that increased body size in overweight children correlated with higher levels of exposure to monoethyl phthalate and to the sum of the low molecular-weight phthalates studied. More research is needed to definitively determine whether phthalate exposure causes increases in body size, but the work does provide evidence that phthalates could contribute to childhood obesity.

Citation Teitelbaum SL, Mervish N, Moshier EL, Vangeepuram N, Galvez MP, Calafat AM, Silva MJ, Brenner BL, Wolff MS. 2012. Associations between phthalate metabolite urinary concentrations and body size measures in New York City children. Environ Res 112:186-193.

The cost of asthma from traffic-related air pollution

NIEHS-funded researchers have estimated that childhood asthma associated with air pollution in Long Beach and Riverside, Calif., costs $18 million each year. Asthma cases attributed to traffic-related pollution contributed to almost half of the cost, and the remaining cost came from asthma exacerbations triggered by traffic-related pollution in children with asthma not caused by air pollution.

According to the researchers, traditional methods for assessing risk from air pollution have underestimated the overall burden of asthma and the costs associated with air pollution. They estimated the annual costs of childhood asthma from traffic-related pollution using their previous estimates of the number of asthma cases attributable to pollution, cost estimates for asthma exacerbations that occur because of regional air pollutants, and information on health care visits by children with asthma. They included a broad range of health care costs such as parents' missed work days, extra doctor visits, travel time, and prescriptions.

The researchers calculated the total annual cost for a typical asthma case to be $3,819 in Long Beach and $4,063 in Riverside. The largest portion of this cost came from asthma-related school absences, which often require that parents or caregivers miss work. The investigators say that their new method takes into account the full impact of traffic-related pollution and can be applied to other urban areas.

Citation Brandt SJ, Perez L, Künzli N, Lurmann F, McConnell R. 2012. Costs of childhood asthma due to traffic-related pollution in two California communities. Eur Respir J; doi: 10.1183/09031936.00157811 [Online 26 Jan 2012]. Story

Childhood exposure to tetrachloroethylene and later mental illness

NIEHS grantees have published a study linking early childhood exposure to the solvent tetrachloroethylene with mental health problems later in life. Tetrachloroethylene is used in dry cleaning and other industries.

Tetrachloroethylene has been shown to increase anxiety and depression, but little is known about how prenatal and early childhood exposure to the solvent affects risk for mental illness. The vinyl liner of water distribution pipes installed in Cape Cod, Mass., from the 1960s to early 1981 led to tetrachloroethylene contamination in drinking water at concentrations from 1.5 to 7,750 parts per billion. The researchers studied people who were born in Cape Cod between 1969 and 1983, including 831 people who experienced prenatal and early childhood tetrachloroethylene exposure, and 547 people who were unexposed. They used questionnaires to gather information on mental illnesses, demographic and medical characteristics, other sources of solvent exposure, and places of residence from birth through 1990.

The study showed that subjects with prenatal and early childhood exposure had an increased risk of bipolar disorder and post-traumatic stress disorder, but not an increased risk for depression. Although the tetrachloroethylene in Cape Cod has been addressed by periodic pipe flushing, people are still exposed to the contaminant in the dry cleaning and textile industries.

Citation Aschengrau A, Weinberg JM, Janulewicz PA, Romano ME, Gallagher LG, Winter MR, Martin BR, Vieira VM, Webster TF, White RF, Ozonoff DM. 2012. Occurrence of mental illness following prenatal and early childhood exposure to tetrachloroethylene (PCE)-contaminated drinking water: a retrospective cohort study. Environ Health 11(1):2. Story

New zebrafish line for studying aryl hydrocarbon receptor

NIEHS-supported researchers have developed a new zebrafish line that expresses a non-functioning aryl hydrocarbon receptor (AHR)2. AHR2 mediates the toxic effects of dioxin, and a functional knockout line for this receptor could help reveal more about its role in toxicological response and other biological processes.

Zebrafish offer a useful model for studying the effects of exposures on development. They have AHR2, AHR1A, and AHR1B versions of the receptor. The researchers used a method called targeting induced local lesions in genomes (TILLING) to create a mutation in the ahr2 gene (ahr2(hu3335)) and then confirmed the absence of AHR2 activity in the resulting mutant line. With the new zebrafish line, investigators can study AHR2 function throughout the organism’s lifespans or examine the function of AHR1A and AHR1B, which has been difficult to do.

Citation Goodale BC, La Du JK, Bisson WH, Janszen DB, Waters KM, Tanguay RL. 2012. AHR2 mutant reveals functional diversity of aryl hydrocarbon receptors in zebrafish. PLoS One 7(1):e29346.

(Nancy D. Lamontagne is a science writer with MDB, Inc., a contractor for the NIEHS Division of Extramural Research and Training, Superfund Research Program, and Worker Education and Training Program.)

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