Clinical significance of hair cadmium content in the diagnosis of mental retardation of children.

Cadmium (Cd) is known to be closely related to the development of children's intelligence. To investigate the clinical significance of the hair cadmium content in the diagnosis of mental retardation (MR), 415 normal and 85 MR children's hair cadmium contents were measured by 79-1 anodic stripping voltmeter. The data were processed by an Apple-II microcomputer. Comparing the median value and using the Chi-square test the Cd contents in the hair of both male and female MR children were obviously higher than those of normal children (P less than 0.001). If the Cd content in the hair of male children is higher than 0.239 microgram/g, and higher than 0.180 microgram/g in the female, MR can be diagnosed. The sensitivity and specificity of the test are greater than 90%; false positive and false negative rates are lower than 10%. Hair Cd can be used as an additional criterion in the diagnosis of MR and may be important in the screening for MR.