Studies on secular changes in the concentration of lead accumulated in organs and rib of Japanese.

As environmental pollution due to waste fluids and gases from factories using lead (Pb), as well as domestic waste materials, has become a matter for public concern, studies on the accumulated levels of Pb in man have become necessary for defining the degree of contamination in the ordinary population. For this purpose, Pb levels in tissues of 76 forensic cadavers were determined in order to investigate the age distribution of accumulated Pb, and 120 samples were used to clarify secular changes in Pb accumulation during the last decade in the general population. The age group showing the highest Pb level was 50-59 years, with mean Pb contents per unit wet weight of 0.262, 0.520, 0.427 and 4.479 micrograms/g for heart, liver, kidney and rib, respectively. Each of these organs in all age groups exhibited almost the same Pb levels, but babies less than one year old had levels close to those in adults. However, ribs in babies exhibited much lower Pb levels. The levels in each organ were lower in individuals over 60 years old. A distinct age-related increase in Pb levels was found only in ribs from age 0 year to 50-59 years. The Pb levels in the heart, liver, kidney and rib showed a decrease during the last 10 years from 0.188 +/- 0.073 to 0.006 +/- 0.003 micrograms/g, from 0.307 +/- 0.169 to 0.076 +/- 0.057 micrograms/g, from 0.287 +/- 0.145 to 0.021 +/- 0.011 micrograms/g and from 3.203 +/- 1.477 to 2.366 +/- 1.469 micrograms/g, respectively.