Associations between water exposure and the development of amyotrophic lateral sclerosis: a matched case-control...

Previous studies have hinted at an association between water exposure and the development of ALS. However, proximity measures to these water sources have been limited to questionnaires or large buffers due to a lack of fine geospatial measures. They also do not distinguish the various classes of hydrographic features. Thus, we created a robust database to investigate the association between proximity to water bodies at place of residence and the development of ALS.

A matched (sex and year of birth) case-control study was conducted in New Brunswick, Canada from January 2003 to February 2021. Study population included 304 ALS patients and 1207 controls with their historical postal codes linked to spatial proximity datasets and air pollution index indicators (proxy measures for contamination by run-off).

Odds of ALS were not significantly associated with proximity to water bodies, even within a 250 m buffer from place of residence (Oceans: 1.10, 0.60-2.00 [95% CI], Reservoirs/Ponds/Lakes: 1.24, 0.47-3.30 [95% CI]). As for interaction models investigating proximity to potentially contaminated water bodies, none of the final fitted models observed an association between proximity to water bodies with indicators of potential run-off sources and the development of ALS.

No significant association between proximity to water bodies at place of residence and the development of ALS were observed in the current study. Future studies should consider taking direct measurements of water quality or utilize geomaps of spraying activities and cyanobacteria blooms alongside proximity measures. Household water quality is another avenue to explore, particularly well water use.