Environ. Sci. Technol. 2007, 41, 4793-4798
Assessment of Exposure of Workers and Swimmers to Trihalomethanes in an Indoor Swimming Pool J. CARO AND M. GALLEGO* Department of Analytical Chemistry, Campus of Rabanales, University of Co´rdoba, E-14071 Co´rdoba, Spain
A simultaneous study on workers’ and swimmers’ exposure to trihalomethanes (THMs) in an indoor swimming pool has been carried out by analyzing urine samples using the headspace and gas chromatography-mass spectrometry technique. The subjects of this study were male and female workers of an indoor swimming pool as well as swimmers regularly attending the pool. The results reported show that only chloroform and bromodichloromethane were detected in the urine of those people exposed, which can be used as a specific index of exposure to these compounds. THM uptake of swimmers after 1 h of swimming was higher than that of workers after a 4 h work shift since THM levels in the workers’ urine were associated only with inhalation, while levels in swimmers’ urine were mainly associated with dermal absorption, apart from inhalation and occasional ingestion, as well as increased uptake due to the physical stress (swimming). The kinetics of THM excretion in the urine of the participants exposed has been calculated after termination of the exposure to select the sampling time and determine the elimination process. An interval of 15 min after exposure was selected as the sampling time, and the absorbed dosage was eliminated by 2 h after exposure. A good correlation between THM concentrations found in the swimming pool water and the urinary THM concentrations of the people affected after exposure has also been obtained.
Introduction Trihalomethanes (THMs) are a byproduct of water chlorination, arising from the reaction between natural organic matter in the source water and chlorine used for disinfection (1). The speciation of the THMs depends on raw water quality and treatment characteristics (2). Based on the increased evidence of adverse health effects linked to these compounds, the U.S. Environmental Protection Agency (EPA) has established a maximum contaminant level of 80 µg/L for the total THMs in drinking water (3). Swimming pool water is treated in a similar way to drinking water using the same disinfecting agents to keep swimmers from infections caused by microbial pathogens. Organic materials of various forms (perspiration, mucus, hair, lotion, etc.) are released into swimming pool water by swimmers (4), and disinfection byproducts, such as THMs, resulting from the chlorination process may reach higher concentrations than those normally found in drinking water. In spite of that, THM levels in swimming pool water have not been legislated to date. * Corresponding author phone: 34-957-211-066; fax: +34-957218-614; e-mail:
[email protected]. 10.1021/es070084c CCC: $37.00 Published on Web 05/19/2007
2007 American Chemical Society
THM concentrations have been determined extensively in drinking waters (5, 6), and swimming pool waters (7, 8). Regarding biological monitoring, Backer et al. (9) determined THMs in the blood of human volunteers following drinking, showering, and bathing, and he found that increases in blood concentrations of THMs from showering or bathing were significantly greater than the increases from drinking 1 L of water. This is because most of the ingested dose is excreted or metabolized rather than absorbed into the blood, while exposure to volatilized THMs by inhalation and dermal absorption resulted in a more direct distribution to the blood and higher blood levels. Whitaker et al. (10) made a simulation study to assess the exposure to chloroform of pregnant women through ingestion of tap water, swimming, bathing, and showering. Their results showed that the uptake was greater for swimming than for showering and bathing, since swimming intensity had a significant impact on chloroform uptake. Alveolar breath sampling was used by Lindstrom et al. (11) to assess the exposure to THMs of collegiate swimmers during a typical 2 h training period. Their results provided evidence that the dermal route of exposure was relatively rapid and ultimately more important than the inhalation route in this training scenario. However, Erdinger et al. (12) found a higher THM uptake through inhalation by analyzing the blood of swimmers and pool guardians, obtaining a good correlation between blood and environmental chloroform concentrations. Blood and breath THM concentrations have also been used as biomarkers of exposure in swimmers by Aggazzotti et al. (13). Individual exposure of swimming pool employees was estimated by THM concentrations in alveolar air (14), obtaining a good correlation between ambient and alveolar air samples. Physiologically based pharmacokinetic models have been used to model the relative uptake from various exposure routes and the distribution of chloroform in the body (15, 16). The use of urinary concentrations of volatile organic compounds (VOCs such as THMs) for biological monitoring of exposure to these compounds is supported by many authors, showing that at constant environmental concentrations during exposure, equilibrium tends to be reached between partial pressure of solvent in external air, alveolar air, arterial blood, body tissues, and mixed venous blood. In the kidneys, the solvent is excreted in urine by a diffusive process determined by the equilibration of partial pressure in the urine and plasma; as a result, the ratio of concentrations in urine and blood tends to equal the urine/blood distribution coefficients (17). Moreover, in spite of the small fraction of THMs excreted in urine (
