PURPOSE

An epidemic of carbon monoxide poisoning suicide by burning charcoal occurred in Hong Kong and Taiwan. An epidemic also emerged in Japan from February 2003 and resulted in an increase of 10-20 % in overall suicide rates in younger adults (aged <45 years) in the mid-2000s. We investigated the spatial and temporal evolution of the epidemic to assess its impact on the epidemiology of suicide in Japan.

METHODS

Mortality data were obtained from the official vital statistics of Japan. Smoothed standardized mortality ratios of charcoal-burning and non-charcoal-burning suicide were estimated for the period 2003-2013 using Bayesian hierarchical models. Joinpoint regression analysis was performed to analyze secular trends in suicide rates by gender, method used and geographic location between 1999 and 2013.

RESULTS

Suicide by burning charcoal rose sharply in the mid-2000s and was not accompanied by a simultaneous decline in alternative methods. The epidemic of charcoal-burning suicide in Japan showed a pronounced spatial pattern, being concentrated in rural prefectures particularly among males. For men but not women, the epidemic contributed to the widening of urban-rural disparities in suicide rates (higher rates in rural areas).

CONCLUSIONS

Our results differ from previous research in other Asian countries (e.g., Taiwan), where the epidemic of charcoal-burning suicide emerged more prominently in urban areas. In Japan, the introduction and diffusion of charcoal burning contributed to a real excess in suicide rates, as well as a widening of the urban/rural disparity in suicide.