Reviews - Multi-Use - Heating - Showers - Pools - Food Preparation - Washing - Non-DW Sources -

General Indoor Exposures


Review Papers & Models on DBPs in the Home
Citation Notes Abstract
Valcke, M. and Krishnan, K. (2010) An Assessment of the Interindividual Variability of Internal Dosimetry during Multi-Route Exposure to Drinking Water Contaminants. International Journal of Environmental Research and Public Health 7(11), 4002-4022.   The objective of this study was to evaluate inter-individual variability in absorbed and internal doses after multi-route exposure to drinking water contaminants (DWC) in addition to the corresponding variability in equivalent volumes of ingested water, expressed as liter-equivalents (LEQ). A multi-route PBPK model described previously was used for computing the internal dose metrics in adults, neonates, children, the elderly and pregnant women following a multi-route exposure scenario to chloroform and to tri- and tetra-chloroethylene (TCE and PERC). This scenario included water ingestion as well as inhalation and dermal contact during a 30-min bathroom exposure. Monte Carlo simulations were performed and distributions of internal dose metrics were obtained. The ratio of each of the dose metrics for inhalation, dermal and multi-route exposures to the corresponding dose metrics for the ingestion of drinking water alone allowed computation of LEQ values. Mean BW-adjusted LEQ values based on absorbed doses were greater in neonates regardless of the contaminant considered (0.129-0.134 L/kg BW), but higher absolute LEQ values were obtained in average adults (3.6-4.1 L), elderly (3.7-4.2 L) and PW (4.1-5.6 L). LEQ values based on the parent compound's AUC were much greater than based on the absorbed dose, while the opposite was true based on metabolite-based dose metrics for chloroform and TCE, but not PERC. The consideration of the 95th percentile values of BW-adjusted LEQ did not significantly change the results suggesting a generally low intra-subpopulation variability during multi-route exposure. Overall, this study pointed out the dependency of the LEQ on the dose metrics, with consideration of both the subpopulation and DWC.
Krishnan, K. and Carrier, R. (2008) Approaches for evaluating the relevance of multiroute exposures in establishing guideline values for drinking water contaminants. Journal of Environmental Science and Health Part C-Environmental Carcinogenesis & Ecotoxicology Reviews 26(3), 300-316.
  .In establishing the guideline values for chemical contaminants in drinking water, the contribution of inhalation and dermal routes associated with showering/bathing needs to be evaluated. The present article reviews the current approaches available for evaluating the importance of inhalation and dermal routes of exposure to drinking water contaminants (DWCs) and integrates them within a 2-tier approach. Accordingly, tier 1 would evaluate whether the dermal or inhalation route is likely to contribute to at least 10% of the dose received from ingestion of drinking water (i.e., 0.15 L-equivalent per day based on the daily water intake rate of 1.5 L/day typically used in Health Canada assessments). Based on the route-specific exposure parameters (i.e., area of skin exposed, effective skin permeability coefficient [K-p], and air to water concentration ratio during use conditions [Fair-water], breathing rate, duration of contact, and fraction absorbed), it was determined that for DWCs with K-p less than 0.024 cm/hr and Fair-water less than 0.0063, the dermal and inhalation routes during showering or bathing are unlikely to contribute significantly to the total dose. For DWCs with K-p value equal to or greater than 0.025 cm/hr, dermal notation is implied, and as such, tier 2 calculation of L-equivalent associated with dermal exposure needs to be performed. Similarly, for DWCs with Fair-water greater than 0.00063, inhalation notation is implied, and detailed evaluation of the L-equivalent associated with inhalation exposure (i.e., tier 2) is suggested. In general, data from human volunteer studies, observational measurements, and targeted modeling studies are useful for deriving L-equivalents, reflective of the magnitude of dose received via dermal and inhalation routes relative to the oral route. However, in resource-limited situations, these approaches can be integrated within a 2-tier approach for prioritizing and providing quantitative evaluations of the relevance of dermal and inhalation routes for developing exposure guidelines for DWCs.


Data on Multi-Indoor Use
Citation Notes Abstract
Chowdhury, S., Rodriguez, M.J. and Serodes, J. (2010) Model development for predicting changes in DBP exposure concentrations during indoor handling of tap water. Science of the Total Environment 408(20), 4733-4743.
  Disinfection by-products (DBPs) in municipal drinking water are a matter of concern because of their possible risks to human health. Risk assessment studies often use measurements of DBPs in water distribution systems, whereas populations are typically exposed to the indoor tap water. Further to this, consumers often employ several indoor strategies to handle tap water (e.g., storing in a refrigerator, boiling, filtering, etc.) prior to use. The indoor handling of municipal water may have implications on DBPs' exposure assessment. This study investigates and develops models to predict the effects of various indoor handling strategies on trihalomethanes (THMs) and haloacetic acids (HAAs). Linear and nonlinear models are developed to predict changes in THM and HAA concentrations due to various indoor water manipulation strategies. The models are capable of assessing representative exposure concentrations of THMs and HAAs as a result of indoor handling, which might be useful in gaining a better understanding of exposure and risks from DBPs in municipal drinking water.
Buteau, S. and Valcke, M. (2010) Probabilistic Human Health Risk Assessment for Quarterly Exposure to High Chloroform Concentrations in Drinking-Water Distribution Network of the Province of Quebec, Canada. Journal of Toxicology and Environmental Health-Part a-Current Issues 73(23), 1626-1644.   Because quarterly concentrations of total trihalomethanes (THM) exceeding the 80 g/L guideline are often tolerated by the public health authorities of the Province of Quebec (Canada), this study examined whether quarterly episodes of high concentrations of THM may pose a risk to the health of its population. Using Monte Carlo simulations, a probabilistic risk assessment was performed for infants (0-6 mo), toddlers (6 mo-5 yr) and adults (epsilon 20 yr). Multiroute exposure including ingestion of drinking water as well as inhalation and dermal exposure while showering or bathing was considered. The resulting absorbed doses were compared to short-term reference values for chloroform, used as surrogate for THM, by calculating risk quotients (RQ). On the basis of THM concentrations values in Quebec's drinking water distribution systems during the months of July to October and exceeding the guideline value (80 g/L), the 95th percentile value of RQ were 0.65, 0.46, and 0.24 for infants, toddlers, and adults, respectively. Back-calculation allowed determining that a chloroform concentration of 330 g/L would result in RQ 1 for 99% of infants, the subgroup considered the most susceptible among the general population. Overall, this study showed that episodes of high THM concentration encountered in Quebec drinking-water distribution network need not be considered as an immediate health concern for the general population. However, these results should not be interpreted as an authorization to exceed the 80 g/L standard but rather as a risk management tool for public health authorities.
Thiriat, N., Paulus, H., Le Bot, B. and Glorennec, P. (2009) Exposure to inhaled THM: Comparison of continuous and event-specific exposure assessment for epidemiologic purposes. Environment International 35(7), 1086-1089.   Trihalomethanes (THMs) (chloroform, bromoform, dibromochloromethane, and bromodichloromethane) are the most abundant by-products of chlorination. People are exposed to THMs through ingestion dermal contact, and inhalation. The objective of this study was to compare two methods for assessing THM inhalation: a direct method with personal monitors assessing continuous exposure and an indirect one with microenvironmental sampling and collection of time-activity data during the main event exposures: bathing, showering and swimming. This comparison was conducted to help plan a future a epidemiologic is stud of the effects of THMs on the upper airways of children. 30 children aged from 4 to 10 years were They wore a 3M (TM) 3520 organic vapor monitor for 7 days. We sampled air in their bathrooms (during baths or showers) and in the indoor swimming pools they visited and recorded their time-activity patterns. We used stainless steel tubes full of Tenax (R) to collect air samples. All analyses were performed with Gas Chromatography and Mass Spectrometry (GC-MS). Chloroform was the THM with the highest concentrations in the air of both bathrooms and indoor swimming pools. Its continuous and event exposure measurements were significantly correlated (r(s)=0.69 p<0.001). Continuous exposures were higher than event exposures, suggesting that the event exposure method does not take into account some influential microenvironments. In an epidemiologic study, this might lead to random exposure misclassification. thus underestimation of the risk, and reduced statistical power. The continuous exposure method was difficult to implement because of its poor acceptability and the fragility of the personal monitors. These two points may also reduce the statistical power of an epidemiologic study. It would be useful to test the advantages and disadvantages of a second sample in the home or of modeling the baseline concentration of THM in the home to improve the event exposure method.
Kim, H. (2008) Seasonal variations in the household exposures of Korean housewives to volatile tap water disinfection by-products. Science of the Total Environment 403(1-3), 59-67.   This study was conducted to compare housewives' winter and summer exposures to volatile disinfection by-products (DBPs) in chlorinated tap water. A total of 60 households were visited for this purpose: 27 in winter and 33 in summer. Each subject was given a questionnaire regarding general tap water use, household ventilation time, and activities related to water use. Tap water, household air, and exhaled breath samples were also collected during the visits. All of the subjects answered that they consumed tap water after either thermal treatment or purification through filtration systems. A longer ventilation time in winter than in summer resulted in a higher inhalation exposure for housewives during that season. Estimated chronic daily intakes calculated for winter and summer showed that in winter, the greatest risk at home is inhalation exposure while resting at home, whereas in summer, it is showering. In both seasons, the ingestion route can be discounted, because tap water is processed before consumption, eliminating the volatile DBPs. From this study, it is evident that the inhalation of household air while resting at home cannot be ignored in risk assessment. Moreover, the fact that water is normally boiled or filtered before use should also be considered.
Villanueva, C.M., Gagniere, B., Monfort, C., Nieuwenhuijsen, M.J. and Cordier, S. (2007) Sources of variability in levels and exposure to trihalomethanes. Environmental Research 103(2), 211-220. many uses including beverage prep In the framework of a cohort study of pregnant women conducted in Brittany (France), we assessed the exposure to trihalomethanes (THM) during pregnancy in a subset by evaluating (1) potential sources of variability in household THM levels; (2) the between- and within-subject variability in THM levels; (3) THM levels in swimming pools; and (4) the role of water-related habits on total THM uptake. We visited 109 women from the ongoing cohort study at home for an interview and collection of tap water from October to December 2004. Forty-three of them were re-contacted to obtain a second tap water sample in April-May 2005. We designed a questionnaire to collect individual information on source and amount of drinking water, frequency of showering, bathing, and swimming pool attendance, and household characteristics. We obtained 282 THM measurements, 152 specifically for the study and 130 from a regulatory agency. Personal information and environmental data were combined using two methodologies (method I using regulatory data and method 2 using our THM measurements) with a different set of assumptions. We calculated ingestion, showering, bathing, and swimming pool THM uptakes and added up those uptakes to calculate total THM uptake. Average THM levels from our measurements in October, November-December, and April-May were 61.3, 45.1, and 54.5 mu g/l, respectively. Geographical variability was low and characteristics of the household did not influence THM levels. Within-subject variability in THM levels was three times higher than between-subject variability. Average THM level in swimming pools was 80.4 mu g/l. Average water consumption during pregnancy was 1.91/day. The source of the household drinking water was 90% bottled, 8% municipal, and 2% from other sources. Forty-seven per cent attended swimming pools during pregnancy. Using method 1, the geometric mean of total THM uptake was 0.93 mu g/day. Showering contributed 64%, swimming in pools 23%, bathing 12%, and drinking water 1% to the total THM uptake. In a setting with low geographical variability and limited environmental measurements, individual data is highly relevant to determine personal THM exposure and uptake. In a population that mainly drinks bottled water (e.g., pregnant women), individual THM uptakes are dominated by inhalation and dermal absorption during, showering, swimming in pools, and bathing.
Yamamoto, K., Kakutani, N., Yamamoto, A. and Mori, Y. (2007) A case study on the effect of storage of advanced treated water in a building's plumbing system on trihalomethane levels. Bulletin of Environmental Contamination and Toxicology 79(6), 665-669. just storage effects? Variations in trihalomethane (THM) levels during two-day period in the advanced treated water which had passed through a building's plumbing system (stored water) were compared with those in the advanced treated water delivered directly by the distribution system. THM levels in both the water were relatively uniform. The water quality deterioration measured by the increased THMs was apparently observed during the storage of the water in the plumbing system, even though the advanced treatment could produce high-quality water. Annual changes in THM in the stored water were also examined. Increasing air temperature increased THMs levels except for bromoform.
Gordon, S.M., Brinkman, M.C., Ashley, D.L., Blount, B.C., Lyu, C., Masters, J. and Singer, P.C. (2006) Changes in breath trihalomethane levels resulting from household water-use activities. Environmental Health Perspectives 114(4), 514-521.   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.
Levesque, S., Rodriguez, M.J., Serodes, J., Beaulieu, C. and Proulx, F. (2006) Effects of indoor drinking water handling on trihalomethanes and haloacetic acids. Water Research 40(15), 2921-2930.   In this study, different tap water handling strategies were investigated to evaluate the effects on two principal chlorinated DBPs, trihalomethanes (THMs) and haloacetic acids (HAAs). Tap water samples collected in the Quebec City (Canada) distribution system on a spatio-temporal basis were subjected to diverse indoor handling scenarios: storing water in the refrigerator, boiling water followed by storage and, finally, filtering water with a point-of-use commercial pitcher also followed by storage. In the first two cases, the use of covered and uncovered pitchers was investigated separately, while in the last case, both the use of new and used filters was compared. In all cases, maximum storage time was 48h. Results demonstrated that in some cases, water handling scenarios have considerable effect, and in other cases, little or no effect. Removal of THM concentrations by simple storage was high (on average 30%) and very high by boiling and filtering with subsequent storage in the refrigerator (on average, 87% and 92%, respectively). In scenarios where water was stored in uncovered pitchers (with or without previous boiling and filtering), the THM decrease was higher for increased storage times. However, storage did not have any effect on HAAs, whereas boiling decreased levels of trichloroacetic acid (TCAA) (on average 42%) and increased levels of dichloroacetic acid (DCAA) (on average 35%), resulting in unchanged average levels of total HAAs. The use of the filtration pitcher decreased HAA levels dramatically (on average 66%). Percentages of change in chlorinated DBPs in the different scenarios varied according to initial concentrations in tap water (baseline water), that is, according to the spatio-temporal variations of these substances in the distribution system. On the basis of these results, the paper discusses implications regarding public health protection and exposure assessment for epidemiological studies.


Water Heating and Boiling
(see: DBP Degradation, for fundamentals on thermal decomposition)
Citation Notes Abstract
Liu, B., Reckhow, D.A. (2011) Northampton Water Heater Studies, Unpublished Manuscript Data to appear in Liu dissertation  
Zhang, X.L., H.W. Yang, X.M. Wang, J. Fu, and Y.F. Xie. 2013. Formation of disinfection by-products: Effect of temperature and kinetic modeling. Chemosphere 90:634-639.
  The temperature of drinking water fluctuates naturally in water distribution systems as well as often deliberately heated for household or public uses. In this study, the temperature effect on the formation of disinfection by-products (DBPs) was investigated by monitoring the temporal variations of twenty-one DBPs during the chlorination of a humic precursors-containing water at different temperatures. It was found that chloroform, DCAA, TCAA, DCAN and CH were detected at the considerable level of tens of ug L-1. The three regulated DBPs (chloroform, DCAA and TCAA) were found increasing with both contact time and water temperature, while the five typical emerging DBPs (DCAN, CH, TCNM 1,1-DCPN and 1,1,1-TCPN) revealed the significant auto-decomposition in addition to the initial growth in the first few hours. Increasing water temperature could enhance the formation rates of all the eight detected DBPs and the decomposition rates of the five emerging DBPs. Further, a kinetic model was developed for the simulation of DBP formation. The validity and universality of the model were verified by its excellent correlation with the detected values of each DBP species at various temperatures. The formation rates of 1,1-DCP and 1,1,1-TCP, and the decomposition rate of 1,1,1-TCP were faster as compared to the other DBPs. And the formation reaction activation energies of CH, DCAN and 1,1-DCP were relatively large, indicating that their occurrence levels in the finished water were more susceptible to temperature variations.
Rahman, M.B., T. Driscoll, M. Clements, B.K. Armstrong, and C.T. Cowie. 2011. Effects of tap water processing on the concentration of disinfection by-products. Journal of Water and Health 9:507-514.
  This study examined the effects on disinfection by-product (DBP) concentrations of common household methods for processing drinking water. Methods: We investigated the effects of refrigerator storage, jug filtering, boiling in an electric kettle, and supply from an instant boiling water unit, with or without filtering, on four species of trihalomethanes (THMs) and nine species of haloacetic acids (HAAs) in water ready for consumption in Sydney, Australia. Water samples were processed in such a way as to simulate real life conditions for drinking filtered water or hot water drinks prepared from tap water drawn from public water supply systems. Results: There was a large reduction in total THMs in kettle-boiled water, instant boiled water, jug-filtered water and instant boiled-filtered water (reductions of 85.8, 93.5, 92.6 and 87.8% of their concentration in tap water respectively). Refrigerator storage did not appear to have a consequential effect on THMs or HAAs. Jug-filtering and instant boiling and filtering resulted in large decreases (77-94%) in all species of HAAs in tap water. Conclusion: This study suggests that different methods of processing tap water can change DBP concentration to an extent that would have a meaningful impact on exposure assessment in epidemiological studies.

Chowdhury, S., Rodriguez, M.J., Sadiq, R. and Serodes, J. (2011) Modeling DBPs formation in drinking water in residential plumbing pipes and hot water tanks. Water Research 45(1), 337-347.

  Disinfection byproducts (DBPs) in municipal supply water are a concern because of their possible risks to human health. Risk assessment studies often use DBP data in water distribution systems (WDS). However, DBPs in tap water may be different because of stagnation of the water in plumbing pipes (PP) and heating in hot water tanks (HWT). This study investigated occurrences and developed predictive models for DBPs in the PP and the HWT of six houses from three municipal water systems in Quebec (Canada) in a year-round study. Trihalomethanes (THMs) in PP and HWT were observed to be 1.4-1.8 and 1.9 -2.7 times the THMs in the WDS, respectively. Haloacetic acid (HAAs) in PP and HWT were observed to be variable (PP/WDS = 0.23-2.24; HWT/WDS = 0.53-2.61). Using DBPs occurrence data from these systems, three types of linear models (main factors; main factors, interactions and higher orders; logarithmic) and two types of nonlinear models (three parameters Logistic and four parameters Weibull) were investigated to predict DBPs in the PP and HWT. Significant factors affecting DBPs formation in the PP and HWT were identified through numerical and graphical techniques. The R(2) values of the models varied between 0.77 and 0.96, indicating excellent predictive ability for THMs and HAAs in the PP and the HWT. The models were found to be statistically significant. The models were validated using additional data. These models can be used to predict DBPs increase from WDS (water entry point of house) to the PP and HWT, and could thereby help gain a better understanding of human exposure to DBPs and their associated risks.
Dion-Fortier, A., Rodriguez, M.J., Serodes, J. and Proulx, F. (2009) Impact of water stagnation in residential cold and hot water plumbing on concentrations of trihalomethanes and haloacetic acids. Water Research 43(12), 3057-3066.   This study demonstrates that levels of trihalomethanes (THMs) increase considerably when cold water stagnates in residential pipes and, more significantly, when water remains in the hot water tank. Levels of haloacetic acids (HAAs) increase as well in both cases, but less significantly in comparison to THMs. The study also demonstrates that in both the plumbing system and residential hot water tank, chlorinated and brominated DBP species do not behave in the same manner. Finally, the study shows that sustained use of water in households helps to maintain THM and HAA levels close to those found in water of the distribution system. The results are useful to identify methods of indoor water use that minimize population exposure to DBPs and improve DBP exposure assessment for epidemiological studies.
Eyring, A., St. Denis, F. and Burlingame, G. (2008) Changes in Water Quality in Premise Plumbing: Cold Water vs. Hot Water, WQTC Proceedings, AWWA. THM, HAA Samples collected from 74 homes in 2006 across the PWD service area (44 in Spring; 30 in fall). PWD uses chloramination at pH 7.2. Samples collected from hot and cold taps that were allowed to run until temperature was stable (at least 2 min). All were analyzed for temperature, chlorine residual, ammonia nitrogen, THMs, HAA8, TOC, TOX and HPC. THM levels increased by up to 15 ug/L (as much as 100% increase) in the hot water. HAA values did not change as much.
Krasner, S.W. and Wright, J.M. (2005) The effect of boiling water on disinfection by-product exposure. Water Research 39(5), 855-864.   Chloraminated and chlorinated waters containing bromide were used to determine the impact of boiling on disinfection by-product (DBP) concentrations. No significant changes were detected in the concentrations of the dihalogenated haloacetic acids (DXAAs) (i.e., dichloro-, bromochloro-, dibromoacetic acid) upon boiling of chloraminated water, whereas the levels of the trihalogenated haloacetic acids (TXAAs) (i.e., trichloro- (TCAA), bromodichloro- (BDCAA), dibromochloroacetic acid (DBCAA)) decreased over time (e.g., 9-37% for TCAA). Increased DXAA concentrations (58-68%) were detected in the boiled chlorinated sample, which likely resulted from residual chlorine reacting with DXAA precursors. TCAA concentration was unchanged after boiling chlorinated water for 1 min, but a 30% reduction was observed after 5 min of boiling. BDCAA concentrations decreased 57% upon boiling for 1 min and were completely removed after 2 min of boiling, whereas DBCAA was removed after boiling chlorinated water for 1 min. Trihalomethane concentrations were reduced in both chloraminated (74-98%) and chlorinated (64-98%) water upon boiling. Boiling chloraminated water for 1 min reduced chloroform concentration by 75%. Chloroform was reduced by only 34% in chlorinated water after a 1 min boil, which indicates that simultaneous formation and volatilization of chloroform was occurring. Most of the remaining DBPs (e.g. haloketones, chloral hydrate, haloacetonitriles) were removed by at least 90% after 1 min of boiling in both samples. These data suggest that other mechanisms (e.g., hydrolysis) may have been responsible for removal of the non-volatile DBPs and further highlight the importance of examining individual species when estimating thermal effects on DBP concentrations.
Wu, W.W., M.M. Benjamin, and G.V. Korshin. 2001. Effects of thermal treatment on halogenated disinfection by-products in drinking water. Water Research 35:3545-3550.
  The influence of heating or boiling on the formation and behavior of disinfection by-products (DBPs) was investigated in DBP-spiked reagent water, municipal tap water, and synthetic water containing chlorinated aquatic humic substances, Thermal cleavage of larger halogenated species leads to both formation of smaller chlorinated molecules (including THMs and HAAs) and dechlorination of organics. In parallel with their formation from larger molecules, THMs can be volatilized, and this latter process dominates the change in their concentration when water is boiled. HAAs are not volatile, but they can be destroyed by chemical reactions at elevated temperatures, with the net effect being loss of trihalogenated HAAs and either formation or loss of less chlorinated HAAs. Although other identifiable DBPs can be generated at slightly elevated temperatures, in most cases their concentrations decline dramatically when the solution is heated.


Showering and Bathing
Citation Notes Abstract
Chowdhury, S. and Champagne, P. (2009) Risk from exposure to trihalomethanes during shower: Probabilistic assessment and control. Science of the Total Environment 407(5), 1570-1578.
  Exposure to trihalomethanes (THMs) through inhalation and dermal contact during showering and bathing may pose risks to human health. During showering and bathing, warm water (35 degrees C-45 degrees C) is generally used. Warming of chlorinated supply water may increase THMs formation through enhanced reactions between organics and residual chlorine. Exposure assessment using THMs concentrations in cold water may under-predict the possible risks to human health. In this study, THMs concentrations in warm water were estimated by developing a THMs formation rate model. Using THMs in warm water, cancer and non-cancer risks to human health were predicted for three major cities in Ontario (Canada). The parameters for risk assessments were characterized by statistical distributions. The total cancer risks from exposure to THMs during showering were predicted to be 7.6. x 10(-6), 6.3 x 10(-6) and 4.3 x 10(-6) for Ottawa, Hamilton and Toronto respectively. The cancer risks exceedance probabilities were estimated to be highest in Ottawa at different risk levels. The risks through inhalation exposure were found to be comparable (2.1 x 10(-6)-3.7 x 10(-6)) to those of the dermal contact (2.2 x 10(-6) -3.9 x 10(-6)) for the cities. This study predicted 36 cancer incidents from exposure to THMs during showering for these three cities, while Toronto contributed the highest number of possible cancer incidents (22), followed by Ottawa (10) and Hamilton (4). The sensitivity analyses showed that health risks could be controlled by varying shower stall volume and/or shower duration following the power law relationship.
Backer, L.C., Lan, Q., Blount, B.C., Nuckols, J.R., Branch, R., Lyu, C.W., Kieszak, S.M., Brinkman, M.C., Gordon, S.M., Flanders, W.D., Romkes, M. and Cantor, K.P. (2008) Exogenous and endogenous determinants of blood trihalomethane levels after showering. Environmental Health Perspectives 116(1), 57-63.   Our goal was to assess the importance of personal characteristics, previous exposures, genetic polymorphisms, and environmental exposures in determining THM concentrations in blood after showering. METHODS: One hundred study participants completed a health symptom questionnaire, a 48-hr food and water consumption diary, and took a 10-min shower in a controlled setting. We examined THM levels in blood samples collected at baseline and 10 and 30 min after the shower. We assessed the significance of personal characteristics, previous exposures to THMs, and specific gene polymorphisms in predicting postshower blood THM concentrations. RESULTS: We did not observe the clustering of blood THM concentrations observed in our earlier study. We found that environmental THM concentrations were important predictors of blood THM concentrations immediately after showering. For example, the chloroform concentration in the shower stall air was the most important predictor of blood chloroform levels 10 min after the shower (p < 0.001). Personal characteristics, previous exposures to THMs, and specific polymorphisms in CYP2D6 and GSTT1 genes were significant predictors of both baseline and postshowering blood THM concentrations as well as of changes in THM concentrations associated with showering. CONCLUSION: The inclusion of information about individual physiologic characteristics and environmental measurements would be valuable in future studies to assess human health effects from exposures to THMs in tap water.
Xu, X. and Weisel, C.P. (2005) Human respiratory uptake of chloroform and haloketones during showering. Journal of Exposure Analysis and Environmental Epidemiology 15(1), 6-16.   Inhalation is an important exposure route for volatile water contaminants, including disinfection by-products (DBPs). A controlled human study was conducted on six subjects to determine the respiratory uptake of haloketones (HKs) and chloroform, a reference compound, during showering. Breath and air concentrations of the DBPs were measured using gas chromatography and electron capture detector during and following the inhalation exposures. A lower percentage oft he HKs (10%) is released from shower water to air than that of chloroform (56%) under the experiment conditions due to the lower volatility of the HKs. Breath concentrations of the DBPs were elevated during the inhalation exposure, while breath concentrations decreased rapidly after the exposure. Approximately 85 - 90% oft he inhaled HKs were absorbed, whereas only 70% of the inhaled chloroform was absorbed for the experiment conditions used. The respiratory uptake of the DBPs was estimated using a linear one-compartment model coupled with a plug flow stream model for the shower system. The internal dose of chloroform normalized to its water concentration was approximately four times that of the HKs after a 30-min inhalation exposure. Approximately 0.3 - 0.4% oft he absorbed HKs and 2 - 9% oft he absorbed chloroform were expired through lung excretion after the 30-min exposure. The inhalation exposure from a typical 10 - 15 min shower contributes significantly to the total dose for chloroform in chlorinated drinking water but only to a moderate extent for HKs.
Xu, X. and Weisel, C.P. (2005) Dermal uptake of chloroform and haloketones during bathing. Journal of Exposure Analysis and Environmental Epidemiology 15(4), 289-296.   Dermal contact with some organic disinfection by-products (DBPs) such as trihalomethanes in chlorinated drinking water has been established to be an important exposure route. We evaluated dermal absorption of two haloketones (1,1-dichloropropanone and 1,1,1-trichloropropanone) and chloroform while bathing, by collecting and analyzing time profiles of expired breath samples of six human subjects during and following a 30-min bath. The DBP concentrations in breath increased towards a maximum concentration during bathing. The maximum haloketone breath concentration during dermal exposure ranged from 0.1 to 0.9 mu g/m(3), which was approximately two orders of magnitude lower than the maximum chloroform breath concentration during exposure. Based on a one-compartment model, the in vivo permeability of chloroform, 1,1-dichloropropanone, and 1,1,1-trichloropropanone were approximated to be 0.015, 7.5 x 10(-4), and 4.5 x 10(-4) cm/h, respectively. Thus, haloketones are much less permeable across human skin under normal bathing conditions than is chloroform. These findings will be useful for future assessment of total human exposure and consequent health risk of these DBPs.

Swimming Pools
Citation Notes Abstract
Dyck, R., Sadiq, R., Rodriguez, M.J., Simard, S. and Tardif, R. (2011) Trihalomethane exposures in indoor swimming pools: A level III fugacity model. Water Research 45(16), 5084-5098.   The potential for generation of disinfection byproducts (DBPs) in swimming pools is high due to the concentrations of chlorine required to maintain adequate disinfection, and the presence of organics introduced by the swimmers. Health Canada set guidelines for trihalomethanes (THMs) in drinking water; however, no such guideline exists for swimming pool waters. Exposure occurs through ingestion, inhalation and dermal contact in swimming pools. In this research, a multimedia model is developed to evaluate exposure concentrations of THMs in the air and water of an indoor swimming pool. THM water concentration data were obtained from 15 indoor swimming pool facilities in Quebec (Canada). A level III fugacity model is used to estimate inhalation, dermal contact and ingestion exposure doses. The results of the proposed model will be useful to perform a human health risk assessment and develop risk management strategies including developing health-based guidelines for disinfection practices and the design of ventilation system for indoor swimming pools.
Weng, S.C., Weaver, W.A., Afifi, M.Z., Blatchley, T.N., Cramer, J.S., Chen, J. and Blatchley, E.R. (2011) Dynamics of gas-phase trichloramine (NCl(3)) in chlorinated, indoor swimming pool facilities. Indoor Air 21(5), 391-399.   Trichloramine (NCl(3)) is recognized as an irritant of the human respiratory system and other tissues. Processes that lead to volatilization from the liquid phase allow for human exposure to gas-phase NCl(3) in swimming pool settings. The dynamics of these processes are not well defined. A N,N-diethyl-p-phenylenediamine/potassium iodide (DPD/KI)-based wet-chemistry method for measuring gas-phase NCl(3) concentration was verified and applied in chlorinated, indoor swimming pool facilities. Other gas-phase oxidants in the air of indoor pools provided interference of 15% or less. The DPD/KI method was applied for the measurement of gas-phase NCl(3) in four chlorinated, indoor swimming pool facilities. All results showed a correlation between bather loading and gas-phase NCl(3) concentration. The nature of swimmer activities also influenced air quality, presumably because of the effects of these activities on mixing near the gas-liquid interface.
Kogevinas, M., Villanueva, C.M., Font-Ribera, L., Liviac, D., Bustamante, M., Espinoza, F., Nieuwenhuijsen, M.J., Espinosa, A., Fernandez, P., DeMarini, D.M., Grimalt, J.O., Grummt, T. and Marcos, R. (2010) Genotoxic Effects in Swimmers Exposed to Disinfection By-products in Indoor Swimming Pools. Environmental Health Perspectives 118(11), 1531-1537.   We evaluated adults who swam in chlorinated pools to determine whether exposure to DBPs in pool water is associated with biomarkers of genotoxicity. METHODS: We collected blood, urine, and exhaled air samples from 49 non-smoking adult volunteers before and after they swam for 40 min in an indoor chlorinated pool. We estimated associations between the concentrations of four trihalomethanes (THMs) in exhaled breath and changes in micronuclei (MN) and DNA damage (comet assay) in peripheral blood lymphocytes before and 1 hr after swimming; urine mutagenicity (Ames assay) before and 2 hr after swimming; and MN in exfoliated urothelial cells before and 2 weeks after swimming. We also estimated associations and interactions with polymorphisms in genes related to DNA repair or to DBP metabolism. RESULTS: After swimming, the total concentration of the four THMs in exhaled breath was seven times higher than before swimming. The change in the frequency of micronucleated lymphocytes after swimming increased in association with higher exhaled concentrations of the brominated THMs (p = 0.03 for bromodichloromethane, p = 0.05 for chlorodibromomethane, p = 0.01 for bromoform) but not chloroform. Swimming was not associated with DNA damage detectable by the comet assay. Urine mutagenicity increased significantly after swimming, in association with the higher concentration of exhaled bromoform (p = 0.004). We found no significant associations with changes in micronucleated urothelial cells. CONCLUSIONS: Our findings support potential genotoxic effects of exposure to DBPs from swimming pools. The positive health effects gained by swimming could be increased by reducing the potential health risks of pool water.
Richardson, S.D., DeMarini, D.M., Kogevinas, M., Fernandez, P., Marco, E., Lourencetti, C., Balleste, C., Heederik, D., Meliefste, K., McKague, A.B., Marcos, R., Font-Ribera, L., Grimalt, J.O. and Villanueva, C.M. (2010) What's in the Pool? A Comprehensive Identification of Disinfection By-products and Assessment of Mutagenicity of Chlorinated and Brominated Swimming Pool Water. Environmental Health Perspectives 118(11), 1523-1530.   We performed a comprehensive identification of DBPs and disinfectant species in waters from public swimming pools in Barcelona, Catalonia, Spain, that disinfect with either chlorine or bromine and we determined the mutagenicity of the waters to compare with the analytical results. METHODS: We used gas chromatography/mass spectrometry (GC/MS) to measure trihalomethanes in water, GC with electron capture detection for air, low- and high-resolution GC/MS to comprehensively identify DBPs, photometry to measure disinfectant species (free chlorine, monochloroamine, dichloramine, and trichloramine) in the waters, and an ion chromatography method to measure trichloramine in air. We assessed mutagenicity with the Salmonella mutagenicity assay. RESULTS: We identified > 100 DBPs, including many nitrogen-containing DBPs that were likely formed from nitrogen-containing precursors from human inputs, such as urine, sweat, and skin cells. Many DBPs were new and have not been reported previously in either swimming pool or drinking waters. Bromoform levels were greater in brominated than in chlorinated pool waters, but we also identified many brominated DBPs in the chlorinated waters. The pool waters were mutagenic at levels similar to that of drinking water (similar to 1,200 revertants/L-equivalents in strain TA100-S9 mix). CONCLUSIONS: This study identified many new DBPs not identified previously in swimming pool or drinking water and found that swimming pool waters are as mutagenic as typical drinking waters.
Lakind, J.S., Richardson, S.D. and Blount, B.C. (2010) The Good, the Bad, and the Volatile: Can We Have Both Healthy Pools and Healthy People? Environmental Science & Technology 44(9), 3205-3210.    
Lee, J., Ha, K.T. and Zoh, K.D. (2009) Characteristics of trihalomethane (THM) production and associated health risk assessment in swimming pool waters treated with different disinfection methods. Science of the Total Environment 407(6), 1990-1997.   Swimming pool water must be treated to prevent infections caused by microbial pathogens. In Korea, the most commonly used disinfection methods include the application of chlorine, ozone/chlorine, and a technique that uses electrochemically generated mixed oxidants (EGMOs). The purpose of this study was to estimate the concentrations of total trihalomethanes (TTHMs) in indoor swimming pools adopting these disinfection methods, and to examine the correlations between the concentrations of THMs and TTHMs and other factors affecting the production of THMs. We also estimated the lifetime cancer risks associated with various exposure pathways by THMs in swimming pools. Water samples were collected from 183 indoor swimming pools in Seoul, Korea, and were analyzed for concentrations of each THM, TOC, and the amount of KMnO(4) consumption. The free chlorine residual and the pH of the pool water samples were also measured. The geometric mean concentrations of TTHMs in the swimming pool waters were 32.9 +/- 2.4 mu g/L for chlorine, 23.3 +/- 2.2 mu g/L for ozone/chlorine, and 58.2 +/- 1.7 mu g/L. for EGMO. The concentrations of THMs differed significantly among the three treatment methods, and the correlation between THMs and TTHMs and the other factors influencing THMs varied. The lifetime cancer risk estimation showed that, while risks from oral ingestion and dermal exposure to THMs are mostly less than 10(-6), which is the negligible risk level defined by the US EPA, however swimmers can be at the greater risk from inhalation exposure (7.77 x 10(-4) - 1.36 x 10(-3)).



Food Preparation
Citation Notes Abstract
Becalski, A., Lau, B.P.Y., Schrader, T.J., Seaman, S.W. and Sun, W.F. (2006) Formation of iodoacetic acids during cooking: Interaction of iodized table salt with chlorinated drinking water. Food Additives and Contaminants 23(10), 957-962.   Iodoacetic and chloroiodoacetic acids were formed when municipal chlorinated tap water was allowed to react with iodized (with potassium iodide) table salt or with potassium iodide itself. Iodoacetic acid was recently shown to be a potent cytotoxic and genotoxic agent. For analysis, samples were extracted with t-amyl methyl ether and converted to the corresponding methyl esters using methanol and sulfuric acid. The concentration of iodoacetic acid was determined by gas chromatography-mass spectrometry (GC-MS) using an authentic standard. The identities of iodoacetic and chloroiodoacetic acids were further confirmed by gas chromatography-high-resolution mass spectrometry (GC-HRMS). Certain influences of sodium hypochlorite and humic acid as well as the concentration of potassium iodide on the yields of these acids were investigated. The concentration of iodoacetic acid in tap water samples boiled with 2 g l(-1) of iodized table salt was found to be in the 1.5 mu g l(-1) range, whilst the concentration of chloroiodoacetic acid was estimated to be three to five times lower.



Dishwashing & Clothes Washing
Citation Notes Abstract
Olson, D.A. and Corsi, R.L. (2004) In-home formation and emissions of trihalomethanes: The role of residential dishwashers. Journal of Exposure Analysis and Environmental Epidemiology 14(2), 109-119.   This study involved an assessment of chloroform formation due to the use of hypochlorite-containing detergents in dishwashers. The objective of this research was to quantify in-home formation of trihalomethanes, particularly as related to dishwasher usage. A series of 14 flask and 15 laboratory experiments were completed. Flask experiments involved the mixing of food with dishwasher detergent in water for a 12-min reaction period, and were intended to identify chemicals and relative levels of those chemicals that may form from dishwasher usage with different food groups. Liquid concentrations of chloroform ranged from 1 to 41 mg/l. Laboratory experiments involved collection of liquid and gas samples over the course of an operating cycle with an actual residential dishwasher. Background concentrations of chloroform in the water supply were generally between 0 and 10 mg/l; liquid chloroform levels in the wash cycle were typically at least 50 mg/l. Chloroform concentrations were as high as 20 mg/l in the dishwasher headspace. Using mass balance equations for a typical residential house and laboratory results from this research, predicted concentrations resulting from dishwasher usage were similar to typical background concentrations in residential dwellings.


Non-Drinking Water Sources
Citation Notes Abstract
Odabasi, M. (2008) Halogenated volatile organic compounds from the use of chlorine-bleach-containing household products. Environmental Science & Technology 42(5), 1445-1451.   Sodium hypochlorite (NaOCI) and many organic chemicals contained in household cleaning products may react to generate halogenated volatile organic compounds (VOCs). Halogenated VOC emissions from eight different chlorine bleach containing household products (pure and diluted) were investigated by headspace experiments. Chloroform and carbon tetrachloride were the leading compounds along with several halogenated compounds in the headspace of chlorine bleach products. One of the most surprising results was the presence of carbon tetrachloride (a probable human carcinogen and a powerful greenhouse gas that was banned for household use by the U.S. Food and Drug Administration) in very high concentrations (Up to 101 mg m(-3)). By mixing surfactants or soap with NaOCI, it was shown that the formation of carbon tetrachloride and several other halogenated VOCs is possible. In addition to quantitatively determined halogenated VOCs (n = 15), several nitrogen-containing (n = 4), chlorinated (n = 10), oxygenated compounds (n = 22), and hydrocarbons (n = 14) were identified in the headspace of bleach products. Among these, 1,1-dichlorobutane and 2-chloro-2-nitropropane were the most abundant chlorinated VOCs, whereas trichloronitromethane and hexachloroethane were the most frequently detected ones. Indoor air halogenated VOC concentrations resulting from the use of four selected household products were also measured before, during, and 30 min after bathroom, kitchen, and floor cleaning applications. Chloroform (2.9-24.6 mu g m(-3)) and carbon tetrachloride (0.25-459 mu g m(-3)) concentrations significantly increased during the use of bleach containing products. During/before concentration ratios ranged between 8 and 52 (25 14, average +/- SD) for chloroform and 1-1170 (146 +/- 367, average SO) for carbon tetrachloride, respectively. These results indicated that the bleach use can be important in terms of inhalation exposure to carbon tetrachloride, chloroform and several other halogenated VOCs.
Martin, J.W., Mabury, S.A., Wong, C.S., Noventa, F., Solomon, K.R., Alaee, M. and Muir, D.C.G. (2003) Airborne haloacetic acids. Environmental Science & Technology 37(13), 2889-2897.   Haloacetic acid (HAA) concentrations were measured in air samples from a semi-rural and a highly urbanized site in southern Ontario throughout 2000 to investigate their sources and gas-particle partitioning behavior. Denuders were efficient for collection of gaseous HAAS, and the particle phase was collected on a downstream quartz filter with negligible breakthrough. Total HAA concentrations (i.e., gas + particles) ranged between <0.025 and 19 ng m(-3) for individual HAAS at both sites. The dominant airborne HAA was monochloroacetic acid (MCA), followed in decreasing order by dichloroacetic acid (DCA),trifluoroacetic acid (TFA), and trichloroacetic acid (TCA). Difluoroacetic acid (DFA), monofluoroacetic acid (MFA), and chlorodifluoroacetic acid (CDFA) were also frequently detected at lower concentrations. Between sites, TFA, DFA, MFA, and TCA concentrations were significantly higher in Toronto, while CDFA concentrations were higher in Guelph. HAAS were primarily in the gas phase all year; however, during colder months, particle-phase HAA concentrations increased relative to the gas phase. Trichloroacetic acid had the highest particle fraction (phi) for all detected HAAS, with a mean phi of 0.51 and 0.56 for Guelph and Toronto, respectively, and both vapor pressure and acid strength appeared to influence gas-particle partitioning. Temporal trends at both sites were partially explained by temperature, short-wave radiation, and particle mass (PM10), leading to indications of the respective sources. A simple deposition model indicated that dry deposition of TFA and TCA should not be neglected in temperate mid-latitude environments and that precipitation concentrations can be successfully predicted by the Henry's law constant.


Papers on General Indoor Chemical Exposure
Citation Notes Abstract
Weschler, C.J. Chemistry in indoor environments: 20 years of research. Indoor Air 21(3), 205-218.
  In the two decades since the first issue of Indoor Air, there have been over 250 peer-reviewed publications addressing chemical reactions among indoor pollutants. The present review has assembled and categorized these publications. It begins with a brief account of the state of our knowledge in 1991 regarding 'indoor chemistry', much of which came from corrosion and art conservation studies. It then outlines what we have learned in the period between 1991 and 2010 in the context of the major reference categories: gas-phase chemistry, surface chemistry, health effects and reviews/workshops. The indoor reactions that have received the greatest attention are those involving ozone-with terpenoids in the gas-phase as well as with the surfaces of common materials, furnishings, and the occupants themselves. It has become clear that surface reactions often have a larger impact on indoor settings than do gas-phase processes. This review concludes with a subjective list of major research needs going forward, including more information on the decomposition of common indoor pollutants, better understanding of how sorbed water influences surface reactions, and further identification of short-lived products of indoor chemistry. Arguably, the greatest need is for increased knowledge regarding the impact that indoor chemistry has on the health and comfort of building occupants. Practical Implications Indoor chemistry changes the type and concentration of chemicals present in indoor environments. In the past, products of indoor chemistry were often overlooked, reflecting a focus on stable, relatively non-polar organic compounds coupled with the use of sampling and analytical methods that were unable to 'see' many of the products of such chemistry. Today, researchers who study indoor environments are more aware of the potential for chemistry to occur. Awareness is valuable, because it leads to the use of sampling methods and analytical tools that can detect changes in indoor environments resulting from chemical processes. This, in turn, leads to a more complete understanding of occupants' chemical exposures, potential links between these exposures and adverse health effects and, finally, steps that might be taken to mitigate these adverse effects.