Changes in breath trihalomethane levels resulting from household water-use activities

Environmental Health Perspectives, April, 2006 by Sydney M. Gordon, Marielle C. Brinkman, David L. Ashley, Benjamin C. Blount, Christopher Lyu, John Masters, Philip C. Singer

Common household water-use activities such as showering, bathing, drinking, and washing clothes or dishes are potentially important contributors to individual exposure to trihalomethanes (THMs), the major class of disinfection by-products of water treated with chlorine. Previous studies have focused on showering or bathing activities. In this study, we selected 12 common water-use activities and determined which may lead to the greatest THM exposures and result in the greatest increase in the internal dose. Seven subjects performed the various water-use activities in two residences served by water utilities with relatively high and moderate total THM levels. To maintain a consistent exposure environment, the activities, exposure times, air exchange rates, water flows, water temperatures, and extraneous THM emissions to the indoor air were carefully controlled. Water, indoor air, blood, and exhaled-breath samples were collected during each exposure session for each activity, in accordance with a strict, well-defined protocol. Although showering (for 10 min) and bathing (for 14 min), as well as machine washing of clothes and opening mechanical dishwashers at the end of the cycle, resulted in substantial increases in indoor air chloroform concentrations, only showering and bathing caused significant increases in the breath chloroform levels. In the case of bromodichloromethane (BDCM), only bathing yielded a significantly higher air level in relation to the preexposure concentration. For chloroform from showering, strong correlations were observed for indoor air and exhaled breath, blood and exhaled breath, indoor air and blood, and tap water and blood. Only water and breath, and blood and breath were significantly associated for chloroform from bathing. For BDCM, significant correlations were obtained for blood and air, and blood and water from showering. Neither dibromochloromethane nor bromoform gave measurable breath concentrations for any of the activities investigated because of their much lower tap-water concentrations. Future studies will address the effects that changes in these common water-use activities may have on exposure. Key words: biomarkers, breath analysis, disinfection by-products, exposure, trihalomethane, water use. doi:10.1289/ehp.8171 available via http://dx.doi.org/[Online 15 November 2005]

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The trihalomethanes (THMs) chloroform (CH[Cl.sub.3]), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform are major by-products of water-disinfection processes involving chlorine [International Agency for Research on Cancer (IARC) 1991]. Typical household activities involving chlorinated water, such as showering, bathing, washing dishes, or drinking tap water, expose individuals to the THMs by inhalation, dermal contact, or ingestion. Such exposure varies from person to person and depends on the individual's water use. A number of studies have found an association between elevated levels of THMs in drinking water and adverse health effects, including bladder (Cantor et al. 1987, 1998; Morris et al. 1992; Vena et al. 1993) and rectal (Hildesheim et al. 1998; Morris et al. 1992) cancers, and birth defects (Bove et al. 1995; Graves et al. 2001).

Common household activities such as showering, bathing, drinking water, and washing clothes and dishes are potentially important contributors to THM exposure (Nieuwenhuijsen et al. 2000; Wallace 1997). Inhalation and dermal contact resulting from showering and bathing have been shown to be significant routes of exposure to THMs (Ashley and Prah 1997; Backer et al. 2000; Miles et al. 2002; Wallace 1997; Weisel and Jo 1996; Weisel et al. 1999). Backer et al. (2000) exposed subjects to THMs in tap water under controlled conditions through ingestion, showering, and bathing, and measured blood concentrations before and after exposure. The levels of the three measurable THMs increased sharply as a result of showering or bathing, but drinking 1 L of tap water resulted in only a small increase. Several other studies have also measured the uptake of THMs from various water-use activities in body fluids, including blood, exhaled breath, and urine. However, the contribution of such activities to the speciation and concentration of THMs in body fluids has not been studied comprehensively. This information would allow us to reliably apportion the contributions of these activities to overall THM exposure and improve the interpretation of data collected in such studies.

Most previous determinations of the uptake of CH[Cl.sub.3] and other THMs by dermal absorption, inhalation, or ingestion resulting from showering, bathing, or drinking water have been based on measurements of exhaled breath (Benoit et al. 1998; Gordon et al. 1998; Jo et al. 1990a, 1990b; Levesque et al. 2002; Wallace 1987, 1997; Weisel and Jo 1996; Weisel et al. 1992, 1999); somewhat fewer have used venous blood (Ashley and Prah 1997; Backer et al. 2000; Lynberg et al. 2001; Miles et al. 2002). The Total Exposure Assessment Methodology (TEAM) study that was conducted between 1979 and 1984 provided a major body of data on THM concentrations at consumers' taps and was also the source of most measurements of personal exposures to airborne CH[Cl.sub.3] (Wallace 1987). The TEAM study indicated, for example, that indoor residential air contributed 25-30% of the combined air-tap-water daily intake of CH[Cl.sub.3] and BDCM (Wallace 1997). Chloroform levels measured in breath after showering have also been found to be correlated with their concentrations in the shower water and air (Jo et al. 1990a; Weisel et al. 1999) and with the time spent carrying out the activity (Gordon et al. 1998).