Most research focuses on THMs as they are considered to represent the greatest risk. Exposure can occur via ingestion, inhalation or dermal absorption. There is evidence to suggest that swimming may lead to the highest THMs levels within the blood (1). After swimming in a chlorinated pool containing DBPs bathers' exhaled breath was found to have an increased concentration of DBPs and the uptake of these DBPs were shown to result in molecular changes to numerous metabolic pathways (2). Bladder cancer risk has been shown to increase with exposure to THMs in chlorinated water at levels regularly occurring in industrialized countries (3). Exposure to THMs were found to restrict Intrauterine growth resulting in small gestational age (1) as well as increasing the risk for early term miscarriage (4).
THMs have been linked to the common ocular, respiratory and cutaneous irritation, inflammation and discomfort associated with working in proximity to chlorinated water. A study of pool employees who worked near the pool found increased prevalence of asthma, red/itchy eyes, eczema, rashes and blocked nose (5). Acute irritation has also been found to occur over the course of a single working shift (6). An increased risk of asthma was found to be correlated to school children’s increased exposure to indoor swimming pools (7) and elite swimmers were found to be more likely to have asthma when compared to other elite athletes (8).
Chloramines are formed when chlorine reacts with ammonia, usually introduced to the pool by human perspiration, saliva, oil, mucus and urine. They are responsible for the “pool smell”. When this smell occurs the pool needs to be shocked to remove this combined chlorine. Chloramines are also a cause of ocular, nasal and dermal irritation (9).
The concentration of DBPs in swimming pool water is typically significantly higher than drinking water. A study of pregnant women found 1% uptake via oral ingestion of drinking water and 23% uptake via inhalation and dermal absorption from swimming pool water (10). There is evidence that THMs concentration can be higher in salt water pools than conventional chlorine pools (11).
Contributions to the water body in addition to natural organic matter such as urine, body oils and body products increase the complexity of the water matrix and subsequent concentration of DBPs (10).
References:
(1) Chlorination Disinfection By-Products in Drinking Water and Congenital Anomalies: Review and Meta-Analyses
Mark J. Nieuwenhuijsen, David Martinez, James Grellier, James Bennett, Nicky Best, Nina Iszatt, Martine Vrijheid, Mireille B. Toledano
Environmental Health Perspective, 2009
(2) Effects of exposure to water disinfection by-products in a swimming pool: A metabolome-wide association study
Karinvan Veldhovena, Pekka Keski-Rahkonenb, Dinesh K.Barupa, Cristina M.Villanueva, Laia Font-Ribera, Augustin Scalbert, Barbara Bodiniera, Joan O.Grimalt, Christian Zwienerh, Jelle Vlaandereni, Lützen Portengeni, Roel Vermeulenai, Paolo Vineis, Marc Chadeau-Hyama, Manolis Kogevina
Environmental International, 2018
(3) Bladder Cancer and Exposure to Water Disinfection By-Products through Ingestion, Bathing, Showering, and Swimming in Pools
Cristina M. Villanueva, Kenneth P. Cantor, Joan O. Grimalt, Nuria Malats, Debra Silverman, Adonina Tardon, Reina Garcia-Closas, Consol Serra, Alfredo Carrato, Gemma Castaño-Vinyals, Ricard Marcos, Nathaniel Rothman, Francisco X. Real, Mustafa Dosemeci, Manolis Kogevinas
American Journal of Epidemiology, 2007
(4) Trihalomethanes in drinking water and spontaneous abortion.
Waller K1, Swan SH, DeLorenze G, Hopkins B.
Epidemiology, 1998
(5) Prevalence of Ocular, Respiratory and Cutaneous Symptoms in Indoor Swimming Pool Workers and Exposure to Disinfection By-Products (DBPs)
Guglielmina Fantuzzi,, Elena Righi, Guerrino Predieri, Pierluigi Giacobazzi, Katia Mastroianni, Gabriella Aggazzotti
International Journal of Environmental Research and Public Health, 2010
(6) Occupational exposure to trichloramine and trihalomethanes: adverse health effects among personnel in habilitation and rehabilitation swimming pools
Jessica Westerlund, Ing-Liss Bryngelsson, Håkan Löfstedt, Kåre Eriksson, Håkan Westberg, Pål Graff
Journal of Occupational Health and Environmental Hygiene, 2019
(7) Lung hyperpermeability and asthma prevalence in schoolchildren: unexpected associations with the attendance at indoor chlorinated swimming pools
A Bernard, S Carbonnelle1, O Michel, S Higuet2, C de Burbure1, J-P Buchet1, C Hermans, X Dumont, I Doyle
Occupational and Environmental Medicine, 2003
(8) Asthma and Swimming: A Meta-Analysis
Michael Goodman, Sean Hays
Journal of Asthma, 2008
(9) Respiratory and Ocular Symptoms Among Employees at Swedish Indoor Swimming Pools
Löfstedt, Håkan MD, PhD; Westerlund, Jessica; Graff, Pål PhD; Bryngelsson, Ing-Liss BSc; Mölleby, Göte RN; Olin, Anna-Carin MD, PhD; Eriksson, Kåre PhD; Westberg, Håkan PhD
Journal of Occupational and Environmental Medicine, 2016
(10) Regulation, formation, exposure, and treatment of disinfection by-products (DBPs) in swimming pool waters: A critical review
Linyan Yang, Xueming Chene, Qianhong She, Guomin Cao, Yongdi Liu, Victor W.-C.Chang, Chuyang Y.Tangh
Environmental International, 2018
(11) Nitrates, chlorates and trihalomethanes in swimming pool water.
J A Beech, R Diaz, C Ordaz, and B Palomeque
Americal Journal of Public Health, 1980
