According to the results of a research study by the Barcelona Institute of Public Health (ISPB), released in a statement, Portugal is among the countries where the concentration of trihalomethanes (THM) compounds have peaks exceeding the maximum 100 micrograms per liter allowed in the European Union (EU) and which are also stipulated in national legislation.l. However, the data compiled by the study indicate that the average annual THM concentration in tap water in Portugal is 23.8 micrograms per liter.
Trihalomethanes (THM) are formed in the process of water disinfection. and are a set of four organic compounds: Chloroform (CHCl3), Bromodichloromethane (CHBrCl2), Dibromochloromethane (CHBr2Cl) and Bromoform (CHBr3). The carcinogenic potential of THM was already known, but the study released now aims to establish a direct relationship between exposure to these compounds and cases of bladder cancer.
“Previous research had established an association between prolonged exposure to THM – either from ingestion, inhalation or dermal absorption – and increased risk of bladder cancer,” the ISPB statement said.
The ISPB analyzed the presence of trihalomethanes in tap water from 26 EU countries, with the exception of Bulgaria and Romania.
As a percentage, the ISPB lists the countries with the highest incidence of bladder cancer cases attributable to THM exposure Cyprus (23%), Malta (17%), Ireland (17%), Spain (11%) and Greece (10%). Portugal has an incidence of 9.1%.
At the opposite extreme are Denmark (0%), the Netherlands (0.1%), Germany (0.2%), Austria (0.4%) and Lithuania (0.4%).
The authors of the study, published in the journal Environmental Health Perspectives, analyzed recent data on THM levels in Europe’s municipal water networks and estimated the disease burden for bladder cancer attributable to exposure to this compound.
“The biggest challenge was collecting representative data on national levels in all EU countries. We hope this data will be more readily available in the future,” said Cristina Villanueva, a researcher who coordinated the study.
The researchers sent questionnaires to municipal water quality authorities requesting information on the total and individual concentration of trihalomethanes in the taps of the distribution network and in the water treatment plants. In addition, data were obtained from other sources, such as online publications, reports and scientific literature.
Data from 2015 to 2018 were obtained from 26 EU countries, covering 75% of the population, which revealed considerable differences between countries.
The average level of trihalomethanes in drinking water was below the EU maximum allowable limit in all countries, but the reported peak concentrations exceeded the limit in nine countries (Cyprus, Estonia, Hungary, Ireland, Italy, Poland, Portugal, Spain and the United Kingdom).
The potential number of bladder cancer cases has been estimated by a statistical calculation linking the average levels of THM with available international information on the incidence rates of this cancer in each country.
In total, researchers concluded that 6,561 bladder cancer cases per year in the EU are attributable to exposure to trihalomethanes.
The authors of the study recommend that countries with the highest THM levels in treated water make efforts to reduce these compounds and estimate that if the 13 countries with the highest THM levels reduced this concentration, 44% of cases could potentially be avoided. annual bladder cancer attributable to exposure to THM.
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