Linear or non-linear -- association of low-level inorganic arsenic exposure from rice with age-standardized mortality risk of cardiovascular disease

To quantify and compare the linear and non-linear associations between local authority level daily per capita inorganic arsenic (iAs) exposure from ingestion of rice (E-iAs_ing,rice) and the age-standardised mortality rates (ASMR) of cardiovascular disease (CVD), an ecological study has been conducted with local authority level iAs exposure and health information obtained from public domain sources for England and Wales. This study reveals that compared with linear models, a non-linear model might be a better fit. In the linear model, E-iAs_ing,rice was observed to be associated with a slight but significant rise in the local authority CVD ASMR both categorically and continuously. In the preferred non-linear model, higher risks of CVD could be observed for local authorities with higher exposure levels but, in contrast to the linear model, CVD ASMR decreased before increasing from 0.3 µg/person/day. Given the otherwise nutritional benefits of rice consumption, this study suggests high rice consumers should eat rice in a smarter way.