Suicide by intentional ingestion of pesticides: a continuing tragedy in developing countries

Abstract

Deliberate self-poisoning has become an increasingly common response to emotional distress in young adults,1 and it is now one of the most frequent reasons for emergency hospital admission.2 In industrialized countries, the drugs that people commonly take in overdose—analgesics, tranquillisers, antidepressants3—are relatively non-toxic. The estimated case fatality for overdose in England, for example, is around 0.5%.4 Most individuals who self-harm do not intend to die. Studies carried out in industrialized countries have found that only 2% go on to commit suicide in the subsequent 12 months.5 In developing countries the situation is quite different.6 The substances most commonly used for self-poisoning are agricultural pesticides.6–11 Overall case fatality ranges from 10% to 20%.12 For this reason, deaths from pesticide poisoning make a major contribution to patterns of suicide in developing nations, particularly in rural areas.6 In rural China, for example, pesticides account for over 60% of suicides.8 Similarly high proportions of suicides are due to pesticides in rural areas of Sri Lanka (71%),13 Trinidad (68%),14 and Malaysia (>90%).10 There is, however, no evidence that levels of suicidal intent associated with pesticide ingestion in these countries are any higher than those associated with drug overdose in industrialized countries, where the drugs taken in overdose are less toxic. In countries where the use of pesticides for self-harm is commonplace conventional epidemiological features of suicide appear to be distorted. In industrialized nations, suicide rates are two to three times higher in men than women, and its incidence tends to increase with age, although in some countries recent rises in young male suicides have distorted this pattern.15 The incidence of non-fatal self-harm in industrialized countries is 20+ times higher than that of suicide; in contrast to suicide, self-harm rates peak in 15–24 year olds and are generally highest in women (Figure 1a).16 A possible explanation for these differences in the age- and sex-patterning of fatal and non-fatal self-harm is that young people, particularly females, are more likely to engage in impulsive acts of self-harm—as indicated by the comparatively lower levels of suicidal intent in young people.17 Because these acts are unplanned, the methods used are those that are readily available at the time of acute distress—prescribed and non-prescribed medicines—and these are relatively non-toxic. If more lethal methods of self-harm, such as pesticides, were favoured and readily accessible in industrialized nations the epidemiology of suicide in these countries might be quite different. Thus the widespread availability of pesticides may contribute to the difference in the age- and sex-patterning of suicide in China,18 Sri Lanka,19 India,20 and several other developing countries compared with that commonly seen in industrialized nations (Figure 2). In these developing countries some of the highest rates are seen in young adults and the ratio of male:female suicide approaches or exceeds unity at this age. In China, whilst suicide rates do tend to increase with age, there is a notable peak in rates amongst males and females aged 20–24 (Figure 2); recent data show that this peak is more prominent in rural localities.18 In rural India rates of suicide in 15–24 year old females are higher than rates in males of the same age and most other female age groups.20 Similar patterns are seen in Sri Lanka (Figure 2). In both China and Sri Lanka pesticides are the most frequently used method of suicide, likewise in India self-poisoning is the commonest method20 and pesticides are the most frequently used agents.9,21 It is of note that the age- and sex-patterns of self-poisoning in Sri Lanka in the younger age groups are similar to those in industrialized countries, (Figure 1b) although in contrast, the case fatality in Sri Lanka is much higher.38 Part of the distinct age- and gender-patterns of suicide deaths in the developing world may therefore reflect a mixture of deaths with high suicidal intent (predominantly in the elderly) and an excess of deaths with low suicidal intent amongst the young where the method chosen for impulsive acts of self-harm (pesticide ingestion) is highly lethal. A possibility strikingly born out in Western Samoa in the 1980s, where two-thirds of all suicides were a result of pesticide ingestion and the age- and sex-patterning of suicide and non-fatal self-harm were almost identical.22 The common use of pesticides for self-harm in part reflects their ease of availability. Whilst their use in agriculture is widespread in industrialized countries, large-scale farming is practised by a small number of landowners, thus reducing the number of people with direct access to pesticides. In contrast, most people living in rural regions of developing countries are involved in agriculture and farm small areas of land. Subsistence farmers keep their own su