Indexes of disinfection by-product (DBPs) exposure and irritant symptoms in swimming pool workers

Exposure to disinfection by-products (DBPs) in indoor swimming pool is regarded as a risk factor for ocular, respiratory and bronchial asthma symptoms in pool workers, although evidence is still inconclusive. Exposure to trichloramine (NCl3) and trihalomethanes (THMs) in relation to the occurrence of irritant symptoms has been evaluated in 165 subjects working in 23 indoor swimming pools. NCl3 was measured in environmental air, while THMs exposure was evaluated using both environmental (water and air) and biological monitoring (alveolar air). Pool water physical-chemical parameters were evaluated as well. Information about workers’ personal data, habits, working tasks and health status was collected using a self-administered questionnaire. NCl3 (660±217 µg/m3) and THMs (98.6±59.9 µg/m3) airborne levels appeared significantly correlated (rs=0.498, p<0.01). THMs in alveolar air (28.9±20.4 µg/m3) were significantly correlated with airborne levels of both THMs (rs=0.624, p<0.01) and NCl3 (rs=0.450, p<0.01). Different acute ocular and respiratory symptoms resulted closely associated both with airborne NCl3 and THMs alveolar air levels; moreover THMs exposure showed a significant correlation with some asthma-related symptoms. Overall, both NCl3 and THMs exposure appeared related to irritant health endpoints in swimming pool workers. NCl3 is probably directly involved in the pathogenic mechanism, however NCl3 analyses are limited to ambient matrix, while for THMs both environmental and personal biological monitoring can be performed. THMs in alveolar air should be, therefore, carefully considered as a proxy measure of exposure to irritant chemicals in epidemiological studies involving swimming pool attendants.