High incidence of suicide by burning in Masjid-i-Sulaiman (southwest of Iran), a polluted area with natural sour gas leakage

Masjid-i-Sulaiman (MIS) is located in the southwest of Iran. Unfortunately, some parts of MIS are contaminated by subsurface leakage of natural gas containing H2S. In order to investigate the possible effect(s) of chronic exposure to sulfur compounds on suicidal behavior, the present study was done. In the 2-year period, 561 individuals attempted suicide (260 men and 301 women). Completed suicide comprised of 19 men and 32 women. The rate per 100,000 person-years was 19.9 for men and 34.8 for women aged over 15 years. Forty-two (13 men and 29 women) of 561 patients were self-immolators by fire with a male:female ratio 0.45. This represents 22.4 burns per 100,000 person-years and is equivalent to 7.4% of all suicide attempts. Thirty-three of 42 patients died (78.6%) who were 9 men and 24 women with male:female ratio 0.37. There is statistically significant differences between sex groups (P(2) = 0.0091). The self-inflicted burn was the most frequent method for lethal suicide. Winter was the most common season for self-burning followed by spring. Statistical analysis showed significant difference between seasons for self-inflicted burn (P(2) = 0.00001). Analysis of correlation showed statistically positive correlation coefficient between mean values of all reactive sulfur compounds and seasonal frequency of suicide (r = 0.923, P(1) = 0.038).