Exposure to Chlorination By‐Products from Hot Water Uses

Studies of disinfection byproducts ( DBPs ) in drinking water and risk of adverse reproductive outcome have usually relied on approximate measures of exposure. Individual differences in consumption of bottled or filtered water, variability in tap water consumption at home and at work, dermal and inhalation exposure to volatile contaminants, and changes in residency during pregnancy may lead to exposure misclassification. We characterized exposures to tap water and other risk factors among 71 pregnant and 43 non -pregnant women attending public health clinics. Nearly all residences had a municipal water source, but 25% of women drank filtered or bottled water. Fifty percent of the women in our sample reported working outside the home where, on average, one third of their daily water intake took place. Pregnant women consumed more water than non -pregnant women ( 3.4 vs. 3.0 total l / day ) , especially cold tap water at home ( 1.8 vs. 1.3 l / day, 95% CI for the difference = 0.1, 0.9 ) . Patterns of showering were similar for both groups of women, but pregnant women were more likely to bathe and to bathe more frequently. The prevalence of smoking was lower among pregnant women ( 22.5% vs. 32.6% ) , as was the consumption of alcohol ( 4.2% vs. 53.5%, 95% CI for the difference = À 64.9, À 33.7 ) . Thirty -two percent of women had moved during their current pregnancy. The data reaffirm the importance of collecting individual -level data for water consumption and exposure to potential confounders to avoid misclassification bias. This study is the first to target women of low socio -economic status ( SES ) and therefore of particular interest in studies of adverse reproductive outcomes for which this group is at increased risk.

Section: Discussionmentioning

confidence: 84%

Exposure to tap water during pregnancy

Zender

Bachand

Reif

2001

“…Weisel and Chen (1994) reported that calculated THM exposure levels were 50% higher when using THM concentrations in heated water than when using THM concentrations in cold water. In our study, THM concentrations were higher in bath or shower water than in cold tap water ( see Table 1) , and blood THM levels in people who showered or bathed were significantly higher than the blood levels of those who drank water.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, these methods may not account for all relevant exposure routes. For example, household water use ( e.g., showering, bathing, flushing toilets, or using the dishwasher, washing machine, or faucets) can result in significant indoor air concentrations of volatile organic compounds ( VOCs ), including DBPs and other contaminants ( e.g., trichloroethylene ) ( Andelman, 1985;Giardino et al, 1992;Weisel and Chen, 1994;Wallace, 1997;Howard -Reed et al, 1999 ), and subsequent VOC exposure through inhalation will vary for different individuals within a household (Wilkes et al, 1996 ) . In addition, DBPs, such as chloroform, can be absorbed through the skin ( Jo et al, 1990a ).…”

Section: Introductionmentioning

confidence: 99%

Household exposures to drinking water disinfection by-products: whole blood trihalomethane levels

Backer

Ashley

Bonin

et al. 2000

145

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.

“…Generally, however, estimates of exposure and risk have assumed that the concentration of THMs in hot water is equivalent to that in cold water and that no reactions of the residual chlorine with organic matter occurs once the water enters the home. Heating of water accelerates the formation of a number of chlorination by -products if a chlorine residual is present ( Weisel and Chen, 1994 ). A doubling of THMs was observed in water heated to 658C for 8 h, which is the period typical of what might occur in a household water heater before a morning shower ( obviously excluding electric power showers which heat water as and when required ).…”

Section: Effect Of Temperature On Uptakementioning

confidence: 95%

“…This would increase the inhalation and dermal exposure and risk associated with showering, by 50% above what would be calculated using the concentration in cold water. In contrast, concentrations of HANs and halopropanones, were found to have decreased to nondetectable levels in the water following heating for 8 h ( Weisel and Chen, 1994 ).…”

Section: Effect Of Temperature On Uptakementioning

confidence: 96%

Uptake of chlorination disinfection by-products; a review and a discussion of its implications for exposure assessment in epidemiological studies

Nieuwenhuijsen

Toledano²,

Elliott³

2000

164

We have reviewed the relevant issues in the exposure assessment of disinfection by -products ( DBPs ) of chlorination for epidemiological and health risk assessment. Various DBPs can be detected in drinking water and swimming pools, and the reported levels show a considerable range, but were generally below the current health standard for total trihalomethanes ( TTHMs ) ( 100 g / l ) . Relatively little information is available on the correlation between the various DBPs in drinking water and in swimming pools. Chloroform was generally, but not always, the most predominant DBP. In epidemiological studies, TTHM levels have been used as an indicator for total DBP load, even though TTHM levels do not always correlate well with individual DPBs. Factors such as residence time, temperature, pH, organic content, including humic and fulvic acid and bromide levels affect the composition and levels of DBPs. Although there are biomarkers of DBPs, mainly for chloroform and more recently for the other volatile trihalomethanes ( THMs ) and the nonvolatile haloacetic acids ( HAAs ) such as trichloroacetic acid ( TCAA ) and dichloroacetic acid ( DCAA ) , they have not been used in epidemiological studies. The THMs have been measured in exhaled breath and serum, while the HAAs have been measured in urine. These biomarkers have been useful to estimate the actual uptake of the DBPs and the relative contribution of various exposure routes. Physiologically based pharmacokinetic ( PBPK ) models exist for, e.g. chloroform, but their main target organs are the kidney and liver and they have not been used in epidemiological studies. Tap water ingestion, showering, bathing, swimming, boiling water and dishwashing are all activities that have been associated with the uptake of DBPs, and considerable variation in these activities has been observed between people. No studies have reported on the correlation between human uptake of DBPs and water -zone mean estimates, but various studies found a good correlation between THM concentrations in exhaled breath and THM concentrations in water during showering and swimming. In general exposure assessment in epidemiological studies has been limited which complicates the interpretation. These findings have implications for epidemiological studies, particularly with reference to Berkson and classical error type models, study power, attenuation and precision of health -risk estimates and study efficiency. Recommendations are made for further areas of study.