The British Journal of Psychiatry (2014) 204, 274–282. doi: 10.1192/bjp.bp.113.135392 Epidemic of charcoal burning suicide in Japan Eiji Yoshioka, Sharon J. B. Hanley, Yasuyuki Kawanishi and Yasuaki Saijo Background Results The charcoal burning suicide epidemics in both Hong Kong In males and females aged 15–24 and 25–44 years, the and Taiwan have been well documented. However, little is charcoal burning epidemic led to a substantial increase in known about the situation in Japan. overall suicides, without a decrease in other methods. In all other age groups, no such trend was observed. Aims To examine the impact of charcoal burning suicide on the Conclusions overall and other method-specific suicide rates between In young Japanese, the charcoal burning method may have 1998 and 2007 in Japan. appealed to individuals who might not have chosen other highly or relatively lethal methods, and consequently led to Method an increase in overall suicides. Using data obtained from the Vital Statistics of Japan, negative binomial regression analyses were performed to Declaration of interest investigate the impact of the charcoal burning method. None. Suicide is an important global healthcare issue, and suicide rates also important.13,14 Compared with the number of population vary according to region, gender, age, time, ethnic origin and, to studies conducted on the impact on overall suicide rates when a a certain extent, practices of death registration.1 In Japan, the specific method is restricted, little attention has been paid to the annual number of suicides rose sharply to 30 000 in 1998, and impact of newly emerging methods on overall suicide rates.7 Thus, has remained high to the present day.2 In 2012, suicide was the the rapid emergence of burning charcoal indoors as a source of seventh major cause of death in Japan. Moreover, the suicide rate toxic carbon monoxide for taking one’s own life provides a unique in Japan is the highest among all high-income countries.2 opportunity to study the impact of method availability on overall Therefore, suicide prevention is a major target of public health suicide rates. Whether a specific method results in death is related efforts. to both its lethal properties and its accessibility, and the case Ajdacic-Gross et al3 used mortality data from the World fatality rate of suicide methods varies greatly.15 The case fatality Health Organization to illustrate great variations in the preferred rates for firearms (80–90%), building jumping (70%), drowning method of suicide across countries. They commented that the (65–80%) and hanging (60–85%) are estimated to be high, main methods of suicide typically change very slowly except for whereas the rate for medication overdose (1.5–4%) is low. The suicide by charcoal burning (carbon monoxide poisoning by case fatality rates for charcoal burning (40–50%), car exhaust burning charcoal in a closed space). Epidemics of charcoal gas (40–60%) and bridge jumping (35–60%) are estimated to be burning suicide in Hong Kong and Taiwan began in the late modest. The case fatality rate of pesticides ingestion (6–75%) 1990s.4–10 In Hong Kong, only 16 people died by suicide from has a comparatively wide range. Therefore, if the charcoal burning charcoal burning in 1998; however, this number increased to suicide method appeals to individuals who would have used other 276 in 2002.4 Similarly, in Taiwan, only 32 people died by suicide highly or relatively lethal methods, the emergence of this method from charcoal burning in 1998, but this number increased to 1346 may consequently result in little or no increase in overall suicide in 2005.5 The dramatic increase in charcoal burning suicide in rates and a substantial decrease in other method-specific suicide Hong Kong and Taiwan is worth noting. In Japan, an epidemic rates. On the other hand, if this method appeals to many individuals of charcoal burning suicide also emerged from 2003.8,11 In who might not have used other highly or relatively lethal methods February 2003, one man and two women, all strangers, formed available, the emergence would lead to a substantial increase in a pact and killed themselves by burning charcoal.8,11 This incident overall suicide rates and little or no decrease in other method- attracted a lot of media attention and initiated a number of specific suicide rates. Reports from both Hong Kong and Taiwan copycat suicide pacts in the following months. Since then, this have indicated that the emergence of charcoal burning methods is disturbing trend has been creeping across Japan, with charcoal associated with an increase in overall suicide rates, and almost no burning frequently used in suicide pacts. The reason for this is decrease in other method-specific suicide rates.4,7,10 However, that charcoal is easily obtained in shops and the method is in Japan, little is known about the impact of charcoal burning recognised as being simple and painless. The Complete Manual suicide on overall and other method-specific suicide rates. of Suicide is a Japanese book written by Wataru Tsurumi,12 which Therefore, in order to address this question, we examined the was first published in 1993. It provides explicit descriptions and impact of the charcoal burning suicide epidemic on overall and analyses of a wide range of suicide methods such as overdosing, other method-specific suicide rates in Japan. hanging, jumping and carbon monoxide poisoning. However, the charcoal burning method was not listed in this book, and as such, was not yet a popular suicide method among Japanese at Method that time. Although social, economic, cultural and psychological factors Data sources are significant contributors to suicide rates there is good evidence The number of deaths from suicide by gender, age (5-year age that the changing availability and popularity of lethal methods is bands) and the ICD-10 codes between 1998 and 2007 was 274 Downloaded from https://www.cambridge.org/core. 23 Sep 2021 at 12:06:20, subject to the Cambridge Core terms of use. Epidemic of charcoal burning suicide in Japan obtained from the Vital Statistics of Japan.16 To identify the whether one or more joinpoints are significant and should be method of suicide, the underlying cause of death according to added to the model. In the final model each joinpoint (if any ICD-10 was used.17 Data on suicide victims 14 years old or was detected) indicates a significant change in the slope. The younger were not analysed in this study. Yearly age standardised maximum number of joinpoints, minimum number of rates were calculated for those aged 15 years and over using the observations from a joinpoint to either end of the data and World Standard population.18 minimum number of observations between two joinpoints were Following ICD-10, all reportable deaths with an external cause set at one, three and four respectively (default settings). The code in the range from X60 to X84, that occurred in the study estimated annual percentage change (EAPC) and 95% confidence period, were classified as suicide.17 For the purpose of this study, interval were estimated for the time segments on both sides of since there is no specific ICD code for suicide from carbon the inflection points. In addition, in order to compare the monoxide poisoning due to charcoal burning, we followed the estimated changes in the age-adjusted suicide rates during the practice that all reportable deaths with an external cause code of overall research period (1998–2007), the pre-epidemic period X67 that satisfied the definition of ‘intentional self-poisoning by (1997–2002) and the epidemic period (2003–2007), the average and exposure to other gases and vapours’ were included as annual percentage change (AAPC) was calculated. The AAPC is charcoal burning suicide.4 Although this approach to coding the a summary measure that is computed, over a fixed interval, as a manner of death has been used before, it is potentially confounded weighted average of the slope coefficients of the joinpoint by the inclusion of suicides by motor vehicle exhaust gas, other regression with the weights equal to the length of each detected carbon monoxide sources, other specified gases and vapours, segment over the interval. When no joinpoint is detected, the and unspecified gases and vapours. Based on data from the AAPC coincides with the EAPC. National Police Agency in Japan, Hitosugi et al11 investigated All analyses, with the exception of the joinpoint regression, the number of suicides by charcoal burning in 2007. They were performed using Stata statistical software, version 12.1, for reported that 8.2% of all suicides were by charcoal burning (males: Macintosh. Statistical significance was defined as a two-tailed 10.0%, females: 4.0%). Based on data from the Vital Statistics of P-value of 50.05. To examine the influence of charcoal burning Japan, 9.9% of reportable deaths with an ‘X60 to X84’ code suicide on overall suicide epidemiology in Japan between 1998 corresponded to those with an X67 code in 2007 (males: 11.9%, and 2007, negative binomial regression analyses were performed females: 4.9%). Therefore, we estimated that in 2007 about 80% using the number of suicides per year and age groups as the of reportable deaths with an X67 code were charcoal burning outcome variable. Negative binomial regression is Poisson suicides. regression with an additional gamma distributed parameter to adjust for overdispersion (extra-Poisson variation) in the data. The regression equation contained a dummy variable (D)asan Period of time under study independent variable that took the value 0 or 1 to indicate the From 1997 to 1998, the number of suicides in Japan had increased pattern of charcoal burning suicide in the pre-epidemic period by 34.7%, and reached more than 30 000 per year.2 The economic (0) or in the epidemic period (1) respectively.