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The assessment of population exposure to chlorination by-products: a study on the influence of the water distribution system.

Legay C, Rodriguez MJ, Sérodes JB, Levallois P - Environ Health (2010)

Bottom Line: The relationship between chlorination by-products (CBPs) in drinking water and human health outcomes has been investigated in many epidemiological studies.Six approaches integrating different considerations for spatial variability of CBP occurrence within different distribution systems are compared.For this purpose, a robust CBP database (i.e., high number of sampling locations selected according to system characteristics) corresponding to nine distribution systems was generated.

View Article: PubMed Central - HTML - PubMed

Affiliation: École supérieure d'aménagement du territoire, Université Laval, Pavillon Antoine Savard, Québec City, QC, G1K 7P4, Canada.

ABSTRACT

Background: The relationship between chlorination by-products (CBPs) in drinking water and human health outcomes has been investigated in many epidemiological studies. In these studies, population exposure assessment to CBPs in drinking water is generally based on available CBP data (e.g., from regulatory monitoring, sampling campaigns specific to study area). Since trihalomethanes (THMs) and haloacetic acids (HAAs) are the most documented CBP classes in drinking water, they are generally used as indicators of CBP exposure.

Methods: In this paper, different approaches to spatially assign available THM and HAA concentrations in drinking water for population exposure assessment purposes are investigated. Six approaches integrating different considerations for spatial variability of CBP occurrence within different distribution systems are compared. For this purpose, a robust CBP database (i.e., high number of sampling locations selected according to system characteristics) corresponding to nine distribution systems was generated.

Results and conclusion: The results demonstrate the high impact of the structure of the distribution system (e.g., presence of intermediary water infrastructures such as re-chlorination stations or reservoirs) and the spatial variability of CBPs in the assigned levels for exposure assessment. Recommendations for improving the exposure assessment to CBPs in epidemiological studies using available CBP data from water utilities are also presented.

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Related in: MedlinePlus

Monthly TTHM levels measured in distribution systems during 2007-2008 (a) Québec City; (b) City of Lévis.
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Figure 2: Monthly TTHM levels measured in distribution systems during 2007-2008 (a) Québec City; (b) City of Lévis.

Mentions: As shown in Table 2, the distribution of TTHM and HAA9 levels (i.e., represented by percentile and standard deviation values) found for each distribution system during the entire period is widespread. Moreover, this phenomenon is more obvious in the AR, DE, LE, SR and CH systems. One explanation for these results was the presence of a substantial temporal variability of water quality during the year in the Québec region. For example, Figures 2a-b illustrate the statistically significant seasonal variations of TTHM levels in 2007-2008. A comparable temporal pattern of TTHM variability was observed for the nine distribution systems for which higher TTHM levels were measured during summer and fall. In the case of HAA9 occurrence, statistically significant temporal variations were also obtained (Figures 3a-b). However, the temporal pattern differed between the distribution systems.


The assessment of population exposure to chlorination by-products: a study on the influence of the water distribution system.

Legay C, Rodriguez MJ, Sérodes JB, Levallois P - Environ Health (2010)

Monthly TTHM levels measured in distribution systems during 2007-2008 (a) Québec City; (b) City of Lévis.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2958998&req=5

Figure 2: Monthly TTHM levels measured in distribution systems during 2007-2008 (a) Québec City; (b) City of Lévis.
Mentions: As shown in Table 2, the distribution of TTHM and HAA9 levels (i.e., represented by percentile and standard deviation values) found for each distribution system during the entire period is widespread. Moreover, this phenomenon is more obvious in the AR, DE, LE, SR and CH systems. One explanation for these results was the presence of a substantial temporal variability of water quality during the year in the Québec region. For example, Figures 2a-b illustrate the statistically significant seasonal variations of TTHM levels in 2007-2008. A comparable temporal pattern of TTHM variability was observed for the nine distribution systems for which higher TTHM levels were measured during summer and fall. In the case of HAA9 occurrence, statistically significant temporal variations were also obtained (Figures 3a-b). However, the temporal pattern differed between the distribution systems.

Bottom Line: The relationship between chlorination by-products (CBPs) in drinking water and human health outcomes has been investigated in many epidemiological studies.Six approaches integrating different considerations for spatial variability of CBP occurrence within different distribution systems are compared.For this purpose, a robust CBP database (i.e., high number of sampling locations selected according to system characteristics) corresponding to nine distribution systems was generated.

View Article: PubMed Central - HTML - PubMed

Affiliation: École supérieure d'aménagement du territoire, Université Laval, Pavillon Antoine Savard, Québec City, QC, G1K 7P4, Canada.

ABSTRACT

Background: The relationship between chlorination by-products (CBPs) in drinking water and human health outcomes has been investigated in many epidemiological studies. In these studies, population exposure assessment to CBPs in drinking water is generally based on available CBP data (e.g., from regulatory monitoring, sampling campaigns specific to study area). Since trihalomethanes (THMs) and haloacetic acids (HAAs) are the most documented CBP classes in drinking water, they are generally used as indicators of CBP exposure.

Methods: In this paper, different approaches to spatially assign available THM and HAA concentrations in drinking water for population exposure assessment purposes are investigated. Six approaches integrating different considerations for spatial variability of CBP occurrence within different distribution systems are compared. For this purpose, a robust CBP database (i.e., high number of sampling locations selected according to system characteristics) corresponding to nine distribution systems was generated.

Results and conclusion: The results demonstrate the high impact of the structure of the distribution system (e.g., presence of intermediary water infrastructures such as re-chlorination stations or reservoirs) and the spatial variability of CBPs in the assigned levels for exposure assessment. Recommendations for improving the exposure assessment to CBPs in epidemiological studies using available CBP data from water utilities are also presented.

Show MeSH
Related in: MedlinePlus