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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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Quarterly average of TTHM levels measured in the nine distribution systems during 2007 (a) 1st quarter; (b) 2nd quarter; (c) 3rd quarter; (d) 4th quarter.
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Figure 4: Quarterly average of TTHM levels measured in the nine distribution systems during 2007 (a) 1st quarter; (b) 2nd quarter; (c) 3rd quarter; (d) 4th quarter.

Mentions: Another explanation for the widespread distribution of CBP levels measured for the distribution systems is the presence of the spatial variability of CBP occurrence within these systems. Figures 4 and 5 present the quarterly average of TTHM and HAA9 levels measured in all sampling sites during 2007, respectively. These figures confirm the statistically significant differences of average CBP levels between the sub-systems of each distribution system (except for the LS system). Figures 4a-d also illustrate the variability within sub-systems of TTHM levels for most systems. The spatial variability between and within sub-systems was also observed for HAA9, but with different patterns (Figures 5a-d). The spatial variability of TTHM and HAA9 levels confirms the influence of the distribution system structure on CBP occurrence, such as the number and the nature of sub-systems (i.e., the type of water supply infrastructure) and the sub-system location within the 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)

Quarterly average of TTHM levels measured in the nine distribution systems during 2007 (a) 1st quarter; (b) 2nd quarter; (c) 3rd quarter; (d) 4th quarter.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: Quarterly average of TTHM levels measured in the nine distribution systems during 2007 (a) 1st quarter; (b) 2nd quarter; (c) 3rd quarter; (d) 4th quarter.
Mentions: Another explanation for the widespread distribution of CBP levels measured for the distribution systems is the presence of the spatial variability of CBP occurrence within these systems. Figures 4 and 5 present the quarterly average of TTHM and HAA9 levels measured in all sampling sites during 2007, respectively. These figures confirm the statistically significant differences of average CBP levels between the sub-systems of each distribution system (except for the LS system). Figures 4a-d also illustrate the variability within sub-systems of TTHM levels for most systems. The spatial variability between and within sub-systems was also observed for HAA9, but with different patterns (Figures 5a-d). The spatial variability of TTHM and HAA9 levels confirms the influence of the distribution system structure on CBP occurrence, such as the number and the nature of sub-systems (i.e., the type of water supply infrastructure) and the sub-system location within the 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