According to the annual report of the Japanese National Police Agency, about 100,000 cases of unnatural death are reported every year. More than 10,0000 of these cases occurred during bathing. In Akita Prefecture, more than 150 cases are reported every year which is represents about 10% of the total unexpected death. According to the epidemiological statistics by our department, sudden death or sudden cardio pulmonary arrest in the hot bath occurs mostly in winter time, from late October to early March, and more than 90% of the decedents are senior population. Although some cardiac or cerebral events might occur during bathing, few cases of those died in the bath tub are autopsied by forensic pathologists. In most cases, the cause of death is suspected by postmortem examination by police surgeon, and the cause of death are generally assigned to ischemic heart attack, cerebral stroke, or unclear cause of drowning. It is often difficult to determine the pathogenesis related to the cause of death in the bathtub even by full autopsy. It is reported that the past and/or present medical history of the deceased persons in the bath tub is reported as hypertension, arrhythmia, ischemic heart disease, or diabetes, it is still unclear what actually triggers a lapse in consciousness in the elderly during bathing. We examined the biodynamic change of elderly volunteers while bathing under actual bathing situations occurring in both the winter and summer seasons. Most subjects decreased the level of blood pressure gradually by bathing regardless the season, and some subjects in the elderly developed ECG changes while bathing such as supraventricular extrasystole or ventricular tachycardia. The body temperature increase to 38°C or more in both the elderly and young groups while bathing. By our observations, lower room temperature in the winter time, hot water immersion may result in risky changes in the above parameters which may partially explain some of the causes of the cases of lapse of consciousness and sudden cardiac arrest in the elderly while bathing.

  According to my experience in forensic practice, some cases of death in our society, such as committing suicide, traffic-related death, and death during bathing are preventable. Regarding suicide in Akita Prefecture, the suicide rate has always been the highest since the end of Showa Era. Also notable is that suicide numbers dramatically increased nationwide to more than 30,000 people in 1998 and to this day still exceed 30,000. In 2006 the Japanese Government enacted a law at preventing suicides. The law seeks to both reduce the number of suicides nationwide as well as establish a social support system. With concerns to traffic-related death, more than 16,000 people were recorded to have died in traffic accidents in 1970, however up until last year this number had gradually decreased to less than 5,000. This is a good example showing that both governmental and non-governmental efforts are necessary in resolving the issue. Unlike the preventable deaths mentioned above, there are no official governmental or local statistics that record death resulting from in hot baths. According to our estimation, approximately 20,000 people might die while bathing. It has already established that sudden death or sudden cardio pulmonary arrest because of entering hot bath water occurs mostly in winter time, and 90% of these cases are of elderly people. Although the extreme hot temperatures of a Japanese- style bath may cause some cardiac or cerebral distress in bathers, only a few cases of bath-related deaths have been autopsied to clarify the cause of death. I would like to emphasize the importance of calling attention to the potential dangers of taking baths in hot water and to the need for us together with the senior citizen population of this danger, as well as their family members by lecture and brochure. Furthermore, more in depth surveys and autopsies need to be performed by medical experts in cases of accidental death during bathing.