Assessing exposure to disinfection by-products in women of reproductive age living in Corpus Christi, Texas, and Cobb county, Georgia: descriptive results and methods.

Abstract

We conducted a field study in Corpus Christi, Texas, and Cobb County, Georgia, to evaluate exposure measures for disinfection by-products, with special emphasis on trihalomethanes (THMs). Participants were mothers living in either geographic area who had given birth to healthy infants from June 1998 through May 1999. We assessed exposure by sampling blood and water and obtaining information about water use habits and tap water characteristics. Two 10-mL whole blood samples were collected from each participant before and immediately after her shower. Levels of individual THM species (chloroform, bromodichloromethane, dibromochloromethane, and bromoform) were measured in whole blood [parts per trillion (pptr)] and in water samples (parts per billion). In the Corpus Christi water samples, brominated compounds accounted for 71% of the total THM concentration by weight; in Cobb County, chloroform accounted for 88%. Significant differences in blood THM levels were observed between study locations. For example, the median baseline blood level of bromoform was 0.3 pptr and 3.5 pptr for participants in Cobb County and Corpus Christi, respectively (p = 0.0001). Differences were most striking in blood obtained after showering. For bromoform, the median blood levels were 0.5 pptr and 17 pptr for participants in Cobb County and Corpus Christi, respectively (p = 0.0001). These results suggest that blood levels of THM species vary substantially across populations, depending on both water quality characteristics and water use activities. Such variation has important implications for epidemiologic studies of the potential health effects of disinfection by-products.

Peer Reviewed: Disinfection Byproducts: The Next Generation

“…At the U.S. Centers for Disease Control and Prevention (CDC) (11,12), NCI, EPA, Health Canada (10), the University of Alberta (Canada) (13), Rutgers University (14,15), and elsewhere, scientists are conducting studies on DBP exposure and uptake in the human body. These investigations will provide more accurate information about individual exposures than the traditionally used water consumption questionnaires and quarterly water treatment plant data.…”

Predictors of personal air concentrations of chloroform among US adults in NHANES 1999–2000

“…Chloroform is formed in treated water by the reaction of chlorine with humic acids and other organic material. Concentrations vary by region, day, and time with reported levels ranging from below detection to maximum values of 100-200 mg/l Backer et al, 2000;Kerger et al, 2000;Lynberg et al, 2001;Gordon et al, 2006). Bench-scale experiments have shown that heating tap water gradually (as in a hot water heater) or boiling can affect point of use levels.…”

“…Using a mass balance approach, water use data, and exposure factor assumptions including 1 mg/l tap water chloroform, McKone (1987) estimated that showering contributes up to 50% of lifetime chloroform inhalation exposures for the average US adult versus spending time in the bathroom or remainder of the house. Additionally, recent biomarker studies of US adults show that showering/bathing is significantly associated with increases in breath and/or blood chloroform, while other household water use activities such as washing dishes or clothes are not (Weisel et al, 1999;Backer et al, 2000;Lynberg et al, 2001;Nuckols et al, 2005;Xu and Weisel, 2005). Swimming in chlorinated pools is also associated with elevated biomarker concentrations though most studies have been conducted outside the United States (Lindstrom et al, 1997;Le´vesque et al, 2000;Erdinger et al, 2004;Caro and Gallego, 2007).…”

Exposure assessment in epidemiologic studies of adverse pregnancy outcomes and disinfection byproducts

“…Meaningful exposure occurs through water ingestion, inhalation, and dermal absorption (Weisel and Jo, 1996;Backer et al, 2000;Lynberg et al, 2001). Although several studies have conducted maternal interviews to obtain information on water consumption and detailed residence information (Shaw et al, 1991;Savitz et al, 1995;Waller et al, 1998;Klotz and Pyrch, 1999), most have based exposure assessment solely on the maternal residence at delivery (Kramer et al, 1992;Aschengrau et al, 1993;Bove et al, 1995;Kanitz et al, 1996;Gallagher et al, 1998;Dodds et al, 1999;Kallen and Robert, 2000;Yang et al, 2000;Jaakkola et al, 2001).…”