Key Point

The volatile organic compound 1,4-DCB is commonly used in mothballs, air fresheners, and toilet bowl deodorizers and has been found to significantly decrease lung function in persons having chronic exposure to the chemical.

NEW ORLEANS—Research triangle park, nc—The general population is exposed to indoor volatile organic compounds (VOCs) in the form of cleaning and degreasing agents, air fresheners, pesticides, toilet bowl deodorizers, tobacco smoke, and building materials such as pressed wood products, carpeting, paints, adhesives, and varnishes. Several studies have found that exposure to VOCs can cause respiratory symptoms, but which are the worst, and how bad are they? The National Institute of Environmental Health Sciences recently published substudy data from the Third National Health and Nutrition Examination Survey (NHANES III): The only compound that had a significant adverse effect on lung function was 1,4-dichlorobenzene (1,4-DCB).1

"Because people spend most of their time indoors, health effects related to VOCs in the residential setting are a concern, particularly with respect to respiratory illness," noted the study authors. A variety of VOCs were measured in a group of NHANES III participants who took part in the Priority Toxicant Reference Range Study. The authors used these data, coupled with pulmonary function test results, to determine the effects of chronic exposure to VOCs.

A total of 953 adults were included in the subset. Lung function measurements included FEV1, FVC, peak expiratory flow rate, and maximum midexpiratory flow rate (MMEFR). All models were adjusted for race/ethnicity, age, gender, and body mass index. The Priority Toxicant Reference Range Study measured blood levels of 11 VOCs with median values above the limit of detection. First, VOCs were analyzed in relation to lung function without adjustment for smoking. Smoking status was then factored into the analysis, because tobacco smoke is a source of VOCs and also affects pulmonary function.

The following potential confounders were also assessed: socioeconomic status, a self-reported doctor diagnosis of emphysema, use of an indoor fireplace or a wood or gas stove for heating and/or cooking within the previous 12 months, age of the participants’ houses, the presence of furred pets at home, and occupational exposure to VOCs. The only factor that met the criteria for confounding was a diagnosis of emphysema.

1,4-DCB LEVELS CORRELATED WITH LUNG FUNCTION DECLINE

The mean age of participants was 36.6. Not surprisingly, acetone was present in higher concentrations than any other VOC, because it is produced endogenously. African-Americans had the highest blood levels of VOCs, and non-Hispanic white people had the lowest levels.

When results were unadjusted according to smoking status, reductions in at least one pulmonary function outcome were significant for 1,4-DCB, benzene, ethylbenzene, styrene, and toluene. However, when smoking status was included in the analysis, only 1,4-DCB was significantly associated with reduced lung function.

The exposure to 1,4-DCB differed among race/ethnicity groups, with African-Americans again having the highest levels of exposure. Across all groups, 1,4-DCB was associated with reductions in all four measures of lung function—significantly so for FEV1 and MMEFR. Interestingly, higher levels of 1,4-DCB were associated with reduced lung function in never smokers and smokers alike. Those with the highest exposure to 1,4-DCB had FEV1 decrements of -153 mL and MMEFR decrements of -346 mL/sec compared to those with the lowest exposure.

"Although VOCs generally do not persist in the blood after termination of acute exposure, after frequent prolonged exposures, blood concentrations can reflect chronic exposures," the authors pointed out. The potential for high exposure to 1,4-DCB exists among persons who regularly use air fresheners, toilet bowl deodorizers, and mothballs. These are products that are replaced when their emissions cease, resulting in chronic exposure.

Indoor air concentrations of 1,4-DCB are much higher than those found outdoors. For instance, levels in some homes and public restrooms can approach 1.64 mg/m3, while normal outdoor concentrations are around 2.0 µg/m3.

"Even a small reduction in lung function may indicate some harm to the lungs," said National Institute of Environmental Health Sciences researcher and lead author Stephanie J. London, MD. "The best way to protect yourself, especially children who may have asthma or other respiratory illnesses, is to reduce the use of products and materials that contain these compounds."

—Gale Jurasek

Reference
1. Elliott L, Longnecker MP, Kissling GE, London SJ. Volatile organic compounds and pulmonary function in the Third National Health and Nutrition Examination Survey, 1988-1994. Environ Health Perspect. 2006;114:1210-1214.

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