Impact of environmental degradation on drinking water and health: A longitudinal epigenetic study

Drinking water is a major exposure route to environmental contaminants. The public health impacts of poor drinking water quality are well known, but the impact on epigenetic ageing is still emerging. This study, for the first time, uses epigenetic age as a means to assess relative regulation-compliant drinking water quality, whilst investigating the impact of a polluted, nutrient enriched sentinel freshwater system, Lough Neagh, on public health in Northern Ireland. This study utilises data from the Northern Ireland Cohort for the study of Longitudinal Ageing (NICOLA), to explore the relationship between drinking water supplied by Lough Neagh, which supplies >40% of Northern Ireland’s drinking water, and epigenetic age in a subsample of an older adult cohort (nmax=1387, mean age = 64.2/SD = 9.4, female = 51.2%). Epigenetic age can be estimated using DNA methylation and several clinical characteristics, to give an estimate of how well the body is ageing. An increased epigenetic age can be indicative of an unhealthy phenotype. In females, significant positive associations were observed between Lough Neagh exposure and the DamAge (coefficient = 3.17, P value = 0.0004), PCPhenoAge (coefficient = 1.6, P value = 0.0005) and zPhysAge clocks (coefficient = 0.03, P value = 0.003), after adjustment for covariates and Bonferroni correction for multiple testing. We also observed spatial variability between water treatment catchment zones, or water supply zones. Lough Neagh water supply may modify epigenetic ageing, and therefore influence other health outcomes, such as cognitive decline. Future studies should focus on identifying other health outcomes associated with polluted drinking water supplies, particularly in the case of Lough Neagh, and potentially problematic contaminants.

Key messages

• This work uses epigenetic age to assess general water quality, and its impact on health. This study helps inform European policy makers on the public health impact of environmental pollution.

• This work investigates the scale of contamination at Lough Neagh, Britain’s largest freshwater lake, and major Northern Irish drinking water source, and its impact on public health.