Risk assessment of trichloramine in the air of indoor swimming pools

The German Working Group on Indoor Guide Values of the Federal Environment Agency and the States' Health Authorities is issuing indoor air guide values to protect public health. For risk assessment of trichloramine in the air of indoor swimming pools few human and animal studies are available. Following short time exposure of a few hours to 0.5 mg trichloramine/m(3), irritation was not reported by recreational swimmers, but occurred after repeated exposure up to 0.4 mg trichloramine/m(3) in competitive swimmers and lifeguards. In the opinion of the Working Group a valid LOAEL for trichloramine in swimming pool indoor air cannot be derived from current studies. Animal studies with repeated inhalative exposure to trichloramine are missing. Accordingly, a toxicologically based indoor air guide value for trichloramine cannot be established. To protect the public against irritation from air in indoor swimming pools the Working Group recommends adopting the planned Swiss technical standard of 0.2 mg trichloramine/m(3) which is supported by toxicological and epidemiological data. The Working Group considers the remaining uncertainties regarding irritation by indoor air trichloramine tenable. Large prospective birth cohort studies indicate that swimming in first year of life did not increase the risk of atopy or asthma. On the contrary, swimming is associated with a decreased prevalence of asthma.