Sri Lanka has produced - through pesticide regulation - the greatest reduction in suicides seen anywhere in the world.
Between 1995 and 2015, an estimated 93,000 lives were saved due to pesticide regulation at the amazing cost effectiveness of less than 50 USD direct costs per life saved (or about 1.4 USD per disability adjusted life year [DALY]). An intervention that costs less per DALY than the GDP for a country is considered by the World Bank to be highly cost effective - the Sri Lankan GDPis about 1000 USD, demonstrating the remarkable power of this approach.
Before the Green Revolution in the 1960s, the annual Sri Lankan suicide rate was quite stable at around 5 per 100,000 population over 8 years of age (see figure). With the introduction of HHPs in the 1960s, the suicide rate steadily rose to 24/100,000 in 1976, followed by a more dramatic rise after 1977 that coincided with Sri Lanka relaxing import trade restrictions. Between 1983 and 1995 the suicide rate plateaued, with a peak rate of 57/100,000 in 1995. Multiple publications over that time reported the growing importance of pesticide poisoning for suicides in the country and Sri Lanka’s role as the world leader country for suicide.
The Pesticide Regulator in Sri Lanka noted this effect of pesticides and started banning the most toxic HHPs, initially parathion and methyl-parathion in 1984 (firsst arrow in the figure). The exponential rise in total (not just pesticide) suicides then stopped; the rate began to fall rapidly after 1995 when five further HHPs were banned including two OP insecticides, methamidophos and monocrotophos, that had become particularly popular after the 1984 bans (2nd arrow). Unfortunately, agricultural practice switched to an organochlorine insecticide, endosulfan (6), which itself had to be banned in 1998 (third arrow). A further ban in 2008 (4th arrow) has allowed the rate to fall even further.
Of note, the major fall in Sri Lankan suicides was not associated with any apparent effect on agricultural costs or yields, indicating that lives can be saved without causing major disruptions to agricultural costs or yields.
Gunnell D, Fernando R, Hewagama M, Priyangika WD, Konradsen F, Eddleston M. The impact of pesticide regulations on suicide in Sri Lanka. Int J Epidemiol. 2007 Dec;36(6):1235-42. https://www.ncbi.nlm.nih.gov/pubmed/17726039
Manuweera G, Eddleston M, Egodage S, Buckley NA. Do targeted bans of insecticides to prevent deaths from self-poisoning result in reduced agricultural output? Environ Health Perspect. 2008 Apr;116(4):492-5. https://www.ncbi.nlm.nih.gov/pubmed/18414632
Pearson M, Zwi AB, Buckley NA, Manuweera G, Fernando R, Dawson AH, McDuie-Ra D. Policymaking 'under the radar': a case study of pesticide regulation to prevent intentional poisoning in Sri Lanka. Health Policy Plan. 2015 Feb;30(1):56-67. https://www.ncbi.nlm.nih.gov/pubmed/24362640
Knipe DW, Metcalfe C, Fernando R, Pearson M, Konradsen F, Eddleston M, Gunnell D. Suicide in Sri Lanka 1975-2012: age, period and cohort analysis of police and hospital data. BMC Public Health. 2014 Aug 13;14:839. https://www.ncbi.nlm.nih.gov/pubmed/25118074
Knipe DW, Chang SS, Dawson A, Eddleston M, Konradsen F, Metcalfe C, Gunnell D. Suicide prevention through means restriction: Impact of the 2008-2011 pesticide restrictions on suicide in Sri Lanka. PLoS One. 2017 Mar 6;12(3):e0172893. https://www.ncbi.nlm.nih.gov/pubmed/28264041