Trihalomethanes (THMs) present in residential drinking water does not cause breast cancer, finds a study at Barcelona Institute for Global Health (ISGlobal).THM is a byproduct of chemical disinfection, long term exposure to this chemical leads to bladder cancer.
The new study, published in Environmental International, assessed whether long-term exposure to THMs was associated with increased breast cancer risk. The study enrolled 2,000 women--half of whom had breast cancer--from various parts of Spain (Asturias, Barcelona, Cantabria, Gipuzkoa, León, Madrid, Navarre and Valencia). It was carried out under the umbrella of the MCC-Spain project.
Participants were interviewed to ascertain residential history, type of drinking water consumed, frequency and duration of showers or baths, as well as major recognized risk factors for breast cancer. Mean adult-lifetime residential levels of chloroform, brominated THMs and the sum of both were calculated.
Laia Font-Ribera, lead author of the study, commented: "At common THM levels for Europe, long-term residential exposure to total THMs is not related to breast cancer." However, the findings do suggest "a moderate association with chloroform in high-exposure cases," explained Font-Ribera, "although more analysis is needed to understand this relationship."
"This epidemiological study eliminated the methodological shortcomings of previous work, but more research is needed to confirm the results," added Villanueva.