Tissue mineral levels in victims of sudden infant death syndrome I. Toxic metals--lead and cadmium.

Lung, liver, kidney, and rib specimens were obtained at autopsy from 66 sudden infant death syndrome (SIDS) infants and 23 infants who died suddenly from other causes between the ages of 4-26 wk. Tissue levels of lead and cadmium were measured by atomic absorption spectroscopy and are expressed as microgram/g dry weight. Because these metals are cumulative with age in storage tissues, the levels were corrected for age (adjusted to age 13 wk). The SIDS liver and rib specimens contained significantly more lead than non-SIDS tissues (liver, 1.095 microgram/g versus 0.761 microgram/g, P less than 0.05; rib, 1.754 microgram/g versus 1.041 microgram/g, P less than 0.01, respectively). There were no significant differences in cadmium concentration between the SIDS and non-SIDS tissues. All four tissues showed significant increases with age in both lead and cadmium concentrations in SIDS. The increase in lung lead concentration with age was significantly greater in SIDS than in non-SIDS cases, P less than 0.05. In non-SIDS only kidney cadmium showed an increase with age (P less than 0.0001). These data collectively suggest an increased exposure of the SIDS infant to lead either prenatally and/or postnatally. Any physiologic effects of the increased tissue lead levels are unknown. They may be only a marker of the known epidemiology of SIDS.