Management of Human Organophosphate Poisoning

Summary Organophosphorus pesticide self-poisoning is an important clinical problem in rural regions of the developing world, and kills an estimated 200 000 people every year. Unintentional poisoning kills far fewer people but is a problem in places where highly toxic organophosphorus pesticides are available. Medical management is difficult, with case fatality generally more than 15%. We describe the limited evidence that can guide therapy and the factors that should be considered when designing further clinical studies. 50 years after first use, we still do not know how the core treatments—atropine, oximes, and diazepam—should best be given. Important constraints in the collection of useful data have included the late recognition of great variability in activity and action of the individual pesticides, and the care needed cholinesterase assays for results to be comparable between studies. However, consensus suggests that early resuscitation with atropine, oxygen, respiratory support, and fluids is needed to improve oxygen delivery to tissues. The role of oximes is not completely clear; they might benefit only patients poisoned by specific pesticides or patients with moderate poisoning. Small studies suggest benefit from new treatments such as magnesium sulphate, but much larger trials are needed. Gastric lavage could have a role but should only be undertaken once the patient is stable. Randomised controlled trials are underway in rural Asia to assess the effectiveness of these therapies. However, some organophosphorus pesticides might prove very difficult to treat with current therapies, such that bans on particular pesticides could be the only method to substantially reduce the case fatality after poisoning. Improved medical management of organophosphorus poisoning should result in a reduction in worldwide deaths from suicide.

Deliberate self-harm is a major problem in the developing world, responsible for around 600 000 deaths in 1990. The toxicity of available poisons and paucity of medical services ensure that mortality from self-poisoning is far greater in the tropics than in the industrialized world. Few data are available on the poisons most commonly used for self-harm in different parts of the world. This paper reviews the literature on poisoning, to identify the important poisons used for self-harm in these regions. Pesticides are the most important poison throughout the tropics, being both common and associated with a high mortality rate. In some regions, particular pesticides have become the most popular method of self-harm, gaining a notoriety amongst both health-care workers and public. Self-poisoning with medicines such as benzodiazepines and antidepressants is common in urban areas, but associated with few deaths. The antimalarial chloroquine appears the most significant medicine, self-poisoning being common in both Africa and the Pacific region, and often fatal. Paracetamol (acetaminophen) is used in many countries but in few has it reached the popularity typical of the UK. Domestic and industrial chemicals are responsible for significant numbers of deaths and long-term disabilities world-wide. Self-poisoning with plant parts, although uncommon globally, is locally popular in some regions. Few of these poisons have specific antidotes. This emphasizes the importance of determining whether interventions aimed at reducing poison absorption actually produce a clinical benefit, reducing death and complication rates. Future research to improve medical management and find effective ways of reducing the incidence of self-harm, together with more widespread provision of interventions proven to be effective, could rapidly reduce the number of deaths from self-poisoning in the developing world.

Asian countries account for approximately 60% of the world's suicides, but there is a great mismatch in the region between the scale of the problem and the resources available to tackle it. Despite certain commonalities, the continent itself is culturally, economically, and socially diverse. This paper reviews current epidemiologic patterns of suicide, including suicide trends, sociodemographic factors, urban/rural living, suicide methods, sociocultural religious influences, and risk and protective factors in Asia, as well as their implications. The observed epidemiologic distributions of suicides reflect complex interplays among the traditional value/culture system, rapid economic transitions under market globalization, availability/desirability of suicide methods, and sociocultural permission/prohibitions regarding suicides. In general, compared with Western countries, Asian countries still have a higher average suicide rate, lower male-to-female suicide gender ratio, and higher elderly-to-general-population suicide ratios. The role of mental illness in suicide is not as important as that in Western countries. In contrast, aggravated by access to lethal means in Asia (e.g., pesticide poisoning and jumping), acute life stress (e.g., family conflicts, job and financial security issues) plays a more important role than it does in Western countries. Some promising suicide prevention programs in Asia are illustrated. Considering the specific socioeconomic and cultural aspects of the region, community-based suicide intervention programs integrating multiple layers of intervention targets may be the most feasible and cost-effective strategy in Asia, with its populous areas and limited resources.