Disinfection Byproducts in Chlorinated or Brominated Swimming Pools and Spas: Role of Brominated DBPs and Association with Mutagenicity
Citation:
Liberatore, H., E. Daiber, S. Ravuri, J. Schmid, S. Richardson, AND D. DeMarini. Disinfection Byproducts in Chlorinated or Brominated Swimming Pools and Spas: Role of Brominated DBPs and Association with Mutagenicity. Journal of Environmental Sciences. Elsevier BV, AMSTERDAM, Netherlands, 117:253-263, (2022). https://doi.org/10.1016/j.jes.2022.04.049
Impact/Purpose:
The U.S. EPA regulates the concentrations of 11 disinfection by-products (DBPs) in drinking water; it was the first country to do so starting in 1979, and it regulates the most DBPs of any country. Disinfection by-products (DBPs) are compounds formed by the reaction of organic material in water with disinfectants such as chlorine or bromine; they are found in drinking water and swimming pool and spa (hot tub) waters. All DBPs tested to date (>100) are genotoxic, and 20/22 tested for carcinogenicity in rodents are carcinogenic. Consequently, all chlorinated drinking water and all chlorinated or brominated swimming pool or hot tub waters ever tested are mutagenic. Studies during the past 15 years have shown that dermal/inhalation exposure (not oral exposure) to high concentrations of a specific class of DBPs, brominated trihalomethanes, in drinking water via showering/bathing or by swimming in disinfected pools, combined with a specific genotype, increases the risk for bladder cancer. Consequently, swimming pools and hot tubs have been used as model systems to replicate the dermal/inhalation exposure to DBPs associated with drinking water-associated bladder cancer. However, there has never been a comprehensive analysis of a large number of DBPs in swimming pool or spa waters to determine which ones are most associated with the mutagenicity of the waters and which ones seem to be formed preferentially in pools and spas but are not present in the tap water. The present study determined the concentrations of 21 DBPs and the sum of the concentrations of various chemical classes of DBPs in 21 different tap, pool, and spa waters. The results showed that the concentrations of 8 individual DBPs were correlated significantly with the mutagenic potencies of the pool and spa waters, and all 8 were brominated DBPs, which included the brominated trihalomethanes mentioned above that are associated with elevated risk for bladder cancer. In addition, the concentrations of the sum of all 5 nitrogen-containing DBPs correlated significantly with the mutagenic potencies of the pool and spa waters. Eight of the 11 DBPs regulated by the U.S. EPA in drinking water are brominated DBPs, but drinking water is also used for showering and bathing. The results from these model studies using swimming pool and spa waters to replicate such dermal/inhalation exposures highlight the importance of the brominated DBPs. In addition, these data also indicate that the nitrogen-containing DBPs, none of which are currently regulated by any country, also correlated with the mutagenic potencies of these waters. Such information can inform future assessments of DBP regulations.
Description:
Although the health benefits of swimming are well-documented, health effects such as asthma and bladder cancer are linked to disinfection by-products (DBPs) in pool water. DBPs are formed from the reaction of disinfectants such as chlorine (Cl) or bromine (Br) with organics in the water. Our previous study (Daiber et al., Environ. Sci. Technol. 50, 6652; 2016) found correlations between the concentrations of classes of DBPs and the mutagenic potencies of waters from chlorinated or brominated swimming pools and spas. We extended this study by identifying significantly different concentrations of 21 individual DBPs in brominated or chlorinated pool and spa waters as well as identifying which DBPs and additional DBP classes were most associated with the mutagenicity of these waters. Using data from our previous study, we found that among 21 DBPs analyzed in 21 pool and spa waters, the concentration of bromoacetic acid was significantly higher in Br-waters versus Cl-waters, whereas the concentration of trichloroacetic acid was significantly higher in Cl-waters. Five Br-DBPs (tribromomethane, dibromochloroacetic acid, dibromoacetonitrile, bromoacetic acid, and tribromoacetic acid) had significantly higher concentrations in Br-spa versus Cl-spa waters. Cl-pools had significantly higher concentrations of Cl-DBPs (trichloroacetaldehyde, trichloromethane, dichloroacetic acid, and chloroacetic acid), whereas Br-pools had significantly higher concentrations of Br-DBPs (tribromomethane, dibromoacetic acid, dibromoacetonitrile, and tribromoacetic acid). The concentrations of the sum of all 4 trihalomethanes, all 11 Br-DBPs, and all 5 nitrogen-containing DBPs were each significantly higher in brominated than in chlorinated pools and spas. The 8 Br-DBPs were the only DBPs whose individual concentrations were significantly correlated with the mutagenic potencies of the tap, pool, and spa waters. These results, along with those from our earlier study, highlight the importance of Br-DBPs in the mutagenicity of these recreational waters.
URLs/Downloads:
DOI: Disinfection Byproducts in Chlorinated or Brominated Swimming Pools and Spas: Role of Brominated DBPs and Association with Mutagenicity