The lead program at CPRI

A lead (Pb) screening program in operation at CPRI in London, Ontario, since 1977 involves simultaneous measurement of blood Pb and erythrocyte protoporphyrin (EP) in a randomized population of physically and/or mentally handicapped children and adolescents on admission, discharge and during outpatient visits. This 11-year study has yielded a large database for computerized evaluation. Based upon log normal transformation of data obtained from the admission and outpatient groups, the normal curve yielded a mean and standard deviation (SD) for blood Pb of 0.36 +/- 0.27 mumol/L (n = 4188). This fosters a downward revision of the upper reference limit to 0.89 mumol/L (95% confidence level). The overall mean for EP was 0.35 +/- 0.37 mumol/L and suggests an upper reference limit of 1.09 mumol/L. The direct correlation between annual means of blood Pb and EP retained its significance (r = 0.80; P less than 0.004). For both blood Pb and EP, there was no significant difference in values between admissions (n = 1455), discharges (n = 1310) and outpatient visits (n = 2963). Only in the case of blood Pb was the overall mean value of males (n = 3822) higher (0.46 +/- 0.34 mumol/L) than that of females (0.39 +/- 0.25 mumol/L; n = 1906), but by t-test the difference was not significant. Although annual means of both blood Pb and EP were highest in 1978 and 79 and lowest in 1987, there was no significant difference between any two years.(ABSTRACT TRUNCATED AT 250 WORDS)