Self-poisoning using pesticides is among the major methods of suicide worldwide, and accounts for one-fifth of suicides in 2006–2010 in South Korea. We investigated long-term trends in pesticide suicide rates in South Korea and factors related to these trends.

We calculated age-standardised rates of pesticide suicide in South Korea (1983–2014) using registered death data. We used graphical approach and joinpoint regression analysis to examine secular trends in pesticide suicide by sex, age and area, and a time-series analysis to investigate association of pesticide suicide rate with socioeconomic and agriculture-related factors. Age, period and cohort effects were examined using the intrinsic estimator method.

Age-standardised rate of pesticide suicide fluctuated between 1983 and 2000 before it markedly increased in 2000–2003 (annual percent change 29.7%), followed by a gradual fall (annual percent change −6.3%) in 2003–2011. Following the paraquat ban (2011–2012), there was a marked reduction (annual percent change −28.2%) in 2011–2014. Trend in pesticide suicide was associated with divorce rate but not with other factors studied. Declines in pesticide suicide in 2003–2011 were most noticeable in younger groups and metropolises; by contrast, elderly adults aged 70+ living in rural areas showed an upward trend until after the 2011–2012 paraquat ban, when it turned downward. In the age–period–cohort modelling, having been born between 1938 and 1947 was associated with higher pesticide suicide rates.

Pesticide suicide trend changed substantially in South Korea over the last three decades. Effective prevention should include close monitoring of trends and strong regulations of toxic pesticides.