Exposure to drinking water disinfection by -products ( DBPs ) , such as trihalomethanes ( THMs ) , has been associated with bladder and colorectal cancer in humans. Exposure to DBPs has typically been determined by examining historical water treatment records and reconstructing study participants' water consumption histories. However, other exposure routes, such as dermal absorption and inhalation, may be important components of an individual's total exposure to drinking water DBPs. In this study, we examined individuals' exposure to THMs through drinking, showering, or bathing in tap water. Thirty -one adult volunteers showered with tap water for 10 min ( n = 11 ) , bathed for 10 min in a bathtub filled with tap water ( n = 10 ) , or drank 1 l of tap water during a 10 -min time period ( n = 10 ) . Participants provided three 10 ml blood samples: one sample immediately before the exposure; one sample 10 min after the exposure ended; and one sample 30 min ( for shower and tub exposure ) or 1 h ( for ingestion ) after the exposure ended. A sample of the water ( from the tap, from the bath, or from the shower ) was collected for each participant. We analyzed water samples and whole blood for THMs ( bromoform, bromodichloromethane, dibromochloromethane, and chloroform ) using a purge -and -trap / gas chromatography / mass spectrometry method with detection limits in the parts -perquadrillion range. The highest levels of THMs were found in the blood samples from people who took 10 -min showers, whereas the lowest levels were found in the blood samples from people who drank 1 l of water in 10 min. The results from this study indicate that household activities such as bathing and showering are important routes for human exposure to THMs.

Volatile organic compounds (VOCs) are a major public health concern, because of their ubiquitous nature and the possible health effects associated with exposure to them. An analytical method has been developed that enabled the determination of parts per trillion levels of 32 VOCs in 10 mL of blood. Special efforts toward reducing blank levels and improving measurement sensitivity have resulted in an analytical method that shows excellent reproducibility and recovery even at these ultratrace levels. Results on normal human blood indicate that quantifiable levels of eleven VOCs can be found in virtually all whole blood samples. In a fraction of the samples, six other VOCs can also be determined at levels above detection limits. This method shows promise as a technique for estimating the normal baseline level of VOCs in human blood and may have future applications in cases of exposure.

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Exposure to certain volatile organic compounds (VOCs) commonly occurs in industrialized countries. We developed a method for measuring 32 VOCs in 10 mL of whole blood at low concentration. We used this method to determine the internal dose of these compounds in 600 or more people in the US who participated in the Third National Health and Nutrition Examination Survey. From our study results, we established a reference range for these VOCs in the general population of the US. We found detectable concentrations of 1,1,1-trichloroethane, 1,4-dichlorobenzene, 2-butanone, acetone, benzene, chloroform, ethylbenzene, m,p-xylene, styrene, tetrachloroethane, and toluene in most of the blood samples of nonoccupationally exposed persons. The accuracy of VOC evaluations depends on the ability of investigators to make sensitive and reproducible measurements of low concentrations of VOCs and to eliminate all sources of interference and contamination.