The number of diatoms recovered from the lungs and other organs in drowning deaths in bathwater

We assessed the plankton levels using the diatom test in the lungs and organs of the circulatory system of nine postmortem cases of bathwater drowning and one case of death due to ischemic heart disease (IHD) while bathing, as well as in the associated bathwater. The number of planktons detected in the lungs was not related to the postmortem period or the process of drowning, but was related to the plankton levels detected in the bathwater taken from the scene. In one case of bathwater drowning, the diatom distribution of the four pulmonary lobes (165.0–280.0 planktons/100 g sample) and other organs (3.6–13.6/100 g) highly corresponded to the pattern of ‘usual’ drowning in water which contains a lot of diatoms. In this case, the bathwater taken from the scene contained a considerable amount of planktons (16.3/100 ml water), which suggests that, when the bathwater is relatively ‘dirty’, the diatom test may be helpful in reaching a diagnosis of drowning. In another case of drowning, a considerable number of diatoms was detected relatively evenly in all four pulmonary lobes (58.3–141.7/100 g), although no planktons were detected in distant organs. In this case, the bathwater also contained a substantial number of planktons (18.8/100 ml), which suggests that a relatively even distribution of planktons in each pulmonary lobe may also support a diagnosis of drowning based on the autopsy findings when the bathwater is relatively ‘dirty’. In the other seven cases of drowning, few planktons were detected in the lungs (0–18.2/100 g) and other organs (0–9.1/100 g) as well as in the associated bathwater (0–3.1/100 ml). These cases suggest that if autopsy findings indicate drowning, the low levels of diatoms detected in both the pulmonary lobes and the bathwater may indicate drowning in clean water. In contrast, in one case of death due to IHD while bathing, no planktons were detected in the organs except for the lower lobe of the right lung (11.8/100 g) and the left kidney (9.1/100 g), although the bathwater contained a sufficient number of planktons by the diatom test (21.3/100 ml). This case suggests that the diatom test may be helpful in distinguishing drowning and other causes of death in bathwater by comparison of the diatom levels in the organs and the bathwater. All of these results indicate that the diatom test may be helpful to differentiate ambiguous cases of drowning in bathwater. However, in this study, although special care and precautions were undertaken, contamination with some planktons could not be prevented. For accurate interpretation and diagnosis, examination and comparison of test results from all four pulmonary lobes, at least four distant organs, and the associated bathwater from the scene of death are necessary together with careful consideration of autopsy findings.