The inhalation effects of by-products from chlorination of heated indoor swimming pools on spinal development in pup mice.

INTRODUCTION: It has been postulated that swimming in heated indoor swimming pools in the first year of life is associated with the development of spinal deformity in children. We explored in pup mice whether exposure to certain disinfection by-products resulting from chlorination of heated pools would affect the future development of the spinal column.

METHODS: Mice, from birth and for 28 consecutive days, were exposed to chemicals known to be created by disinfection by-products of indoor heated swimming pools. The study made use of a body fluid analogue and a chlorine source to recreate the conditions found in municipal pools. A cohort of 51 wild-type C57B6 mice, male and female, were divided into two groups: experimental (n = 29) and controls (n = 22). 24 mice were observed for 8 months (32 weeks), with 27 culled at 4 months (16 weeks). Serial CT scanning was used to assess the spines.

RESULTS: Exposure to disinfection by-products resulted in an increase in the normal thoracic kyphotic spinal angle of the mice when compared with their controls at 10 weeks; experimental mice kyphosis range 35-82° versus 29-38° in controls. At 14 weeks the kyphosis of the experimental mice had reduced in size but never to that of the control group.

CONCLUSION: We have demonstrated the ability to influence spinal development in pup mice through environmental factors and shown that the developmental deformity became evident only after a significant latent period.