ARKHANGELSK, May 28. /TASS/. Shower gels, shampoos and other detergents may be a source of toxic compounds in pool water, Director of the Arctic Center for Collective Use of Scientific Equipment at the Northern Arctic Federal University Dmitry Kosyakov told TASS. During the study, scientists for the first time analyzed transformation of the cocamidopropyl betaine (CAPB) substance and found that upon contact with chlorine-containing products, potentially dangerous compounds are formed from it.
"It was for the first time that we focused on cocamidopropyl betaine. When you buy shampoo, about half of it will be CAPB. It gets into the pool water in large quantities. Nobody has studied what happens further on as it was believed to be a rather non-reactive compound. In our study, we found that it forms a significant number of different products. The problem is that in the long run the pool ends up with a large mixture of products from a wide variety of compounds that come from human sweat, cosmetics, hair products, shampoos, and various water treatment reagents. They transform into hundreds of different products. Though in every case the doses are small and harmless to human health, when all together, they would be floating in the pool water and will not be beneficial for humans," the center's director said.
Scientists have begun to explore xenobiotics - organic compounds alien to nature that form various transformation products during water disinfection. "Among most toxic and most dangerous products are nitrogen-containing products, including CAPB. When they are chlorinated for disinfection, develop chlorine-and nitrogen-containing compounds, all of which are highly toxic. Therefore, it is very important to analyze and study how those nitrogen-containing compounds are transformed during water disinfection," he explained.
CAPB transformations
Cocamidopropyl betaine is a surfactant. It is chemically synthesized from coconut oil. When reacting with chlorine-containing products, it forms many products, including dimethylcarbamoyl chloride, which is highly toxic and carcinogenic.
The center's specialists modeled and studied formation of chlorination products of CAPB. Earlier, CAPB was considered resistant to chlorine. The products of its chlorination form in small quantities, and their search and identification require complex analytical chemistry methods. The scientists used liquid and two-dimensional gas chromatography in combination with high-resolution mass spectrometry. The transformation products toxicity was assessed by using computer modeling. The more halogen atoms, in our case chlorine, appear in their structure, the more dangerous they are for humans due to affecting the blood, kidneys and respiratory system.
In tests, water samples from the pool showed the initial CAPB concentration of 0.8 micrograms per 1 liter and 18 primary products of its transformation, including 10 chlorine-containing ones (with a total concentration of 0.1 micrograms per 1 liter), which are noticeably toxic to aquatic organisms and have an adverse effect on health. Mass spectrometry revealed previously unknown classes of water disinfection by-products: hydroxy-CAPB and hydroxychlorine-CAPB that form due to pool water's UV treatment.
"This does not mean that water in swimming pools does not comply with current hygiene standards and poses an immediate danger to their visitors. Moreover, the positive effects of swimming on human health are likely to outweigh the negative effects of impurities in the water. However, their formation and long-term effect on the body requires careful study," the expert concluded.
Improving water purification methods
Results of such studies will be used to improve existing and create new water treatment technologies. Chlorine needs alternatives, the scientist stressed. One of them is bromine, which some countries use to disinfect water. Bromine's key advantages are no unpleasant odor and bleaching effect. However, organobromine compounds are also toxic.
Another water treatment method is ozonation. But, the scientist noted, in using ozone, potentially harmful compounds may also be obtained. "There is no clear solution to what technology can solve the problem. The current approach is that it is necessary to change water treatment technologies so that to minimize formation of potentially dangerous compounds, even in small concentrations. This is a big branch of science," he added.