BLOOD LEAD LEVELS IN CHILDREN AGED 24 TO 36 MONTHS IN VANCOUVER

Objectives: To determine the blood lead levels in children and to iden tify risk factors for elevated levels. Design: Cross-sectional study. Setting: Vancouver. Participants: Random sample of children aged 24 to 36 months, born and still resident in Vancouver. The sample was strat ified proportionally by the median annual family income in the census tract where each family resided. Outcome measures: Blood lead levels a nd risk factors for elevated blood lead levels, determined from a ques tionnaire administered to parents. Results: Of the children in the sam ple, 42% (178/422) were ineligible or could not be located. Of the rem aining children, 73% (177/244) participated and adequate blood specime ns were obtained from 172. The mean blood lead level was 0.29 mu mol/L (standard deviation 0.13 mu mol/L). (A blood lead level of 1 mu mol/L is equivalent to 20.7 mu g/dL.) The lowest level was 0.06 mu mol/L, a nd the highest was 0.85 mu mol/L. Of children with adequate samples, 8 .1% (14/172) had blood lead levels of 0.48 mu mol/L or higher, and 0.6 % (1/172) had a level higher than 0.72 mu mol/L. The logarithms of the levels were normally distributed, with a geometric mean (GM) of 0.26 mu mol/L (geometric standard deviation 1.56). Of approximately 70 poss ible predictors of blood lead levels analysed, those that showed a sta tistically significant association (p < 0.05) with increased blood lea d levels were soldering performed in the home as part of an electronic s hobby (GM blood lead level 0.34 mu mol/L, 95% confidence interval [C I] 0.27 to 0.39 mu mol/L), aboriginal heritage (GM blood lead level 0. 33 mu mol/L, 95% CI 0.28 to 0.39 mu mol/L), dwelling built before 1921 (GM blood lead level 0.32 mu mol/L, 95% CI 0.28 to 0.37 mu mol/L), ag e of water service connection to dwelling (predicted blood lead level 0.00087 mu mol/L [95% CI 0.00005 to 0.00169 mu mol/L] higher per year since service connection) and decreased stature (predicted blood lead level 0.018 mu mol/L [95% CI 0.0353 to 0.0015 mu mol/L] higher for eve ry standard deviation below the age-specific mean height). Conclusions : This study found much lower blood lead levels in children than those found in previous Canadian studies. The authors believe that this res ult is not an artefact due to differences in population sampling or me thods of collection of blood specimens. The study showed no clear risk factors for elevated blood lead levels: although a few factors had a statistically significant association with increased blood lead levels , the differences in levels were small and unimportant.