Severe lead contamination among children of samurai families in Edo period JapanNakashima T, Matsuno K, Matsushita M, Matsushita T (2011) 38: 23-28

Lead is widely found in nature and commonly used in industry; levels in the environment have risen significantly since industrialisation. Measurements of lead levels in bones, the main site of storage, is an indicator of prolonged exposure. Poisoning can cause gastrointestinal symptoms, irritability and fatigue, with progression to confusion, peripheral neuropathy, encephalopathy and seizures. Poisoning has been well documented in adult industrial workers, and is now recognised as a major health problem in children. In children, the symptoms of poisoning are often the more severe, and can potentially lead to death.

The aim of this study is to provide evidence of lead contamination amongst the samurai people of Japan. The authors of this study have previously established that high levels of lead contamination have been found in a castle town in Japan, populated by samurai and merchant classes. They also imply that lead poisoning is involved in the fall of the Roman Empire, where large quantities were consumed by richer Romans in their diet.

Rib bones were excavated from a samurai burial ground and divided into age groupings based on anatomical findings. Atomic absorption spectrometry was performed to determine the level of lead present in the bones. A Mann-Whitney test was then performed to compare results between the groups.

The results of this study show a significantly elevated level of lead found in the bones of children, compared to adults. The highest levels were found in the youngest age group of three years and under, which were 50 times higher than of adult females. Levels amongst females were also found to be higher than males; this is presumed to be as a result of facial cosmetics, particularly white lead, which was popular in this time. The study then goes on to theorise that the close relationship between mothers and young children, especially when nursing is responsible for the high levels amongst the younger children. Contamination was factored out by testing levels in the soil.

This study does not hypothesise on potential implications of its findings on modern society, where lead consumption is higher as a result of lead pollution. In particular, raised lead levels in the waterways means fish and sea food are potential sources of ingestion.