Exposure assessment to disinfection byproducts: from personal exposure assessment to population health
Date Issued
November 2017
Author(s)
Advisor
Abstract
Exposure to disinfection byproducts (DBP) affects large population groups around the
world, thus any association with adverse outcomes should be known. Trihalomethanes
(THM) are a representative group of DBP and their exposure distribution and health
effects are often used as surrogates for the whole class of DBP. THM comprise of
chloroform, bromodichloromethane, dibromochloromethane and bromoform, all of
which are known to exhibit hepatotoxic effect in high concentrations. This study aimed
to assess the different tools for exposure assessment, population differences as well as
metabolic markers of exposure and possible health outcomes related to exposure to THM.
The methodologies included personal exposure assessment, environmental monitoring,
biomonitoring of biomarkers of exposure and effect and untargeted metabolomics along
with extensive statistical analysis. Factors such as geography, climate conditions,
lifestyle, environment, chemical exposures, and endogenous processes were integrated,
showing the various stages and steps towards the comprehensive assessment of the
exposome.
Through this project we were able to point out significant country differences in urine
levels of THM in populations of Cyprus, Kuwait, Norway and the Netherlands. An
exposure gradient from North to South was seen, with increasing median [IQR] urinary
total THM levels from Norway (199 [76-486] ng/g), the Netherlands (340 [174-596]
ng/g), Cyprus (691 [510-919] ng/g) to Kuwait (1044 [814-1270] ng/g). Both, external
(e.g. exposure sources, habits) and internal (e.g. metabolism) factors influenced the THM
biomarker levels and the biomarkers of effect. While under a high THM exposures
(cleaning activities), differences in metabolomic profiles in urine were observed, this was
not obvious under low exposures. Populations in Norway and the Netherlands, exposed to low levels of THM based on their urinary THM levels, showed no specific metabolic
changes. This research provides additional insight for methodological improvement in
THM exposure assessment and the basis for targeted hypothesis-driven investigation
towards improved dose-response assessment and safe exposure levels.
world, thus any association with adverse outcomes should be known. Trihalomethanes
(THM) are a representative group of DBP and their exposure distribution and health
effects are often used as surrogates for the whole class of DBP. THM comprise of
chloroform, bromodichloromethane, dibromochloromethane and bromoform, all of
which are known to exhibit hepatotoxic effect in high concentrations. This study aimed
to assess the different tools for exposure assessment, population differences as well as
metabolic markers of exposure and possible health outcomes related to exposure to THM.
The methodologies included personal exposure assessment, environmental monitoring,
biomonitoring of biomarkers of exposure and effect and untargeted metabolomics along
with extensive statistical analysis. Factors such as geography, climate conditions,
lifestyle, environment, chemical exposures, and endogenous processes were integrated,
showing the various stages and steps towards the comprehensive assessment of the
exposome.
Through this project we were able to point out significant country differences in urine
levels of THM in populations of Cyprus, Kuwait, Norway and the Netherlands. An
exposure gradient from North to South was seen, with increasing median [IQR] urinary
total THM levels from Norway (199 [76-486] ng/g), the Netherlands (340 [174-596]
ng/g), Cyprus (691 [510-919] ng/g) to Kuwait (1044 [814-1270] ng/g). Both, external
(e.g. exposure sources, habits) and internal (e.g. metabolism) factors influenced the THM
biomarker levels and the biomarkers of effect. While under a high THM exposures
(cleaning activities), differences in metabolomic profiles in urine were observed, this was
not obvious under low exposures. Populations in Norway and the Netherlands, exposed to low levels of THM based on their urinary THM levels, showed no specific metabolic
changes. This research provides additional insight for methodological improvement in
THM exposure assessment and the basis for targeted hypothesis-driven investigation
towards improved dose-response assessment and safe exposure levels.
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