CREAL and IDEA-CSIC have published a study of trihalomethanes (THMs) in swimming pools that use bromoform to disinfect the water instead of chlorine. Although most pools in Catalonia are chlorinated, brominated compounds have different characteristics compared to chlorinated and deserve special attention. The results show that bromoform predominates in the mixture of disinfection by-products in pools where use bromoform for disinfection. Likewise they have found that chloroform is the dominant product in chlorinated pools.
Furthermore, it was found that bromoform predominates in the air of swimming pools, with concentrations correlated with the levels in water. However, airborne concentrations of bromoform represent approximately 6-11% of the theoretically expected concentrations.
The study also highlights that bromoform in exhaled air of swimmers is correlated with the concentrations in the air within the installation of the pool. Comparison of THM levels in expired air between the swimmers and volunteers who don’t swim or who stay out of the swimming pools suggest an increasing during physical activity of the exposure to these compounds. They also indicate that in pools, as well as inhalation, dermal absorption is an important pathway for the incorporation of THM.
It added that bromine agents tend to be more toxic, according to experimental studies in cells (in vitro). Not classified as carcinogenic in humans because no human data, while for the chloroform we have it.
Manolis Kogevinas, CREAL joint scientific director; Cristina Villanueva, head of the CREAL research program 'Water pollution' and Laia Font-Ribera have participated in this study.
THM and Health Effects
We must explain that all compounds formed in the process water disinfection by-products are collectively called disinfection byproducts (DPB). Trihalomethanes (THMs) are a group of disinfection byproducts formed when chlorine is used as a disinfectant. THMs majority found in drinking water are chloroform, bromodichloromethane (BDCM), the dibromochloromethane (DBCM) and bromoform.
Epidemiological studies associate with certain exposures in trihalomethanes (THM) and, in general, exposure to disinfection byproducts with health effects such as bladder cancer. Studies of bladder cancer find an increased risk due to long exposure to THMs (30 years) although the results are not always significant. The International Agency for Research on Cancer (IARC) classifies chloroform and bromodichlorometane as possibly carcinogenic to humans under certain exposure conditions. This means that although there is evidence of carcinogenicity in experimental animals, the evidence is limited in humans. Bromoform and dibromochlorometane not classified as carcinogens