In the current study, we investigated pesticide self-poisoning cases and consequent deaths in Jiangsu, China, over a 13-year interval. Our data indicated that while Jiangsu province has witnessed a decreasing trend in self-poisoning with pesticides from 2006 to 2018 (p < 0.05). Since 2007, the GDP per capita, Divorce rate had increased and % population in farming, Pesticide sold (10000 ton), % Engel coefficient, Unemployment rate had decreased, and the number of pesticide suicides has dropped by 76.77%. But since 2014, the number of suicides has declined steadily, so we need to find a new key point to reduce the self-poisoning with pesticides.
Globally, the male suicide rate is three times higher than that of females[11, 12]. However, this high male-to-female ratio is primarily a phenomenon in high-income countries, with the 2012 ratio of age-standardized suicide rates being reported as 3.5. In Lower Middle Income Countries the male-to-female ratio is a significantly lower at 1.6, indicating that the proportion of suicide is 57% higher in men than in women[2]. In the current study, the proportion of pesticide self-poisoning in females was significantly higher than that in males (p < 0.001). The higher number of self-poisoning cases in females may be due to low intent suicidal behaviour[13]. Self-poisoning with pesticides, especially among women, may be used to gain attention, express distress or get revenge, and not necessarily to end life[14, 15]. Traditionally, suicide is an influential method for people (particularly women), in particular, those with low status, to prove their innocence or protest against unfair treatment[16].
According to age, the proportion of suicides were highest in people aged 65 years or older for both men and women worldwide and lowest for people aged less than 15 years. However, age and sex patterns also changed from one region to another[2]. In some regions, the proportion of suicides increased steadily with age while in others, it peaked in young adults and subside in middle age[17]. Notably, suicide cases at 40 years of age were highly reported. Suicide in adults aged 30–49 years accounted for 4.1% of all deaths and represented the fifth major cause of death in China. In addition, incidents of death due to pesticide poisoning increased stepwise with age. China has a different pattern of suicides, with the highest rates reported within the elderly population, compared to other countries[18]. Poor health, increased number of comorbidities, high susceptibility to pesticide poisoning and post-poisoning complications are contributory factors to poor prognosis of the older population in China[19].
The proportion (%) of self-poisoning with pesticide cases and related deaths were mainly clustered in Northern Jiangsu, accounting for 58.01% of patients in the Province of Jiangsu. In rural areas of China, acquisition of pesticides is relatively easy. Agricultural practices in developed and developing nations are significantly different as less labour is used for cultivation of land in developed nations[20]. Consequently, pesticides are not easily obtainable as they are only available to individuals involved in farming practices while in the less developed regions, pesticides are easily available near homes. Interventions to limit access in such settings are complex and require the involvement of most rural adults, rather than a select few.
Previous research has shown that the incidence of self-poisoning with pesticides quarterly in a year due to season-specific agricultural activities, with high the proportion of suicides correlating with availability of pesticides during the farming season[21, 22]. Consistent with earlier findings, we observed higher the proportion of self-poisoning with pesticides in the farming season. Interestingly, case fatality rate due to pesticide self-poisoning were highest in March but decreased during the farming season. This was mainly related to the causes of suicide in China. The most striking and puzzling difference between Chinese suicide cases and those from Western countries is the relative importance of mood disorders and other psychopathological conditions as determinants of suicidal behaviour. Mental illness is virtually omnipresent in western literature as a serious risk for suicide but appears to play a less relevant role in Asia, especially China and India[7, 22, 23]. This finding implied that in at least one third of all global suicides, psychiatric disorders do not represent the most relevant risk factor[24].
Our study showed that suicide induction with organophosphate and carbamate insecticides was the most common with a total of 10,303 cases, which accounted for 42.02% of all cases. Overall, insecticides were the main agents utilized for self-poisoning (19,002, 77.50%). The case fatality rate using organophosphate and carbamate insecticides was significantly higher than those with other pesticides (p < 0.001). Organophosphate and carbamate insecticides, such as T60.0 × 2, were the most commonly used agents, which could be attributed to their prevalent domestic use for controlling mosquitoes and other insects[21]. Although organophosphates and carbamates are most commonly used for agricultural purposes, pyrethroid and other insecticides, such as allethrin, cypermethrin and permethrin, are more frequently used for public health in China. About 73.6% suicides used pesticides stored in the home, mainly insecticides with medium or high toxicity[25]. Studies from other countries have revealed a strong relationship between agent availability and method selected to commit suicide[26]. Method availability may also affect the threshold at which negative life events precipitate suicidal behaviour[27]. This could present further evidence of the relationship between the common use of pesticides for self-poisoning in rural areas and higher the proportion of suicides in China.
With the increase of GDP per capita, the number of suicides had decreased, showing that people's suicide had a strong negative correlation with per capita GDP. That is, increasing per capita GDP was a key point to reduce pesticide suicide. In addition, the strong correlation between the % population living in households involved in farming and pesticide suicide indicated that pesticide supervision was still weak in agricultural cultivation areas, and it was necessary to improve supervision. Furthermore, there was a strong positive correlation between the decline in cases of pesticide suicide and the decline in pesticide sold, especially since the ban on highly toxic pesticides in 2007, the number of deaths from pesticide suicides had decreased significantly.
Suicide prevention strategies focusing on mental disorders may not be the most effective approach for rural China. The government should formulate appropriate policies for the actual situation of local pesticide usage for suicides. First, mental health education in areas with large agricultural populations, such as northern Jiangsu, should be improved. Second, better care for the elderly, who present with the highest the proportion of pesticide suicide, is an essential step. Third, the most important and effective strategy is to increase the management of pesticides and community interventions during the farming season, which should effectively reduce the number of impulsive suicide attempts. Finally, there was a need to strengthen the management of pesticides, because the second largest the proportion of pesticide suicide was mainly caused by unspecified pesticides.