Performance of several decision support tools for determining the need for systematic screening of childhood lead poisoning around industrial sites

Background: Living around industrial sites may expose young children to lead and cause elevated blood lead levels (BLLs). Systematic screening for childhood lead poisoning is necessarily invasive but may be appropriate, depending on children's exposure levels. Our objective was to assess the performance of several decision support tools for determining the need for systematic BLL screening in children around industrial sites. Method: We used several exposure models to predict BLLs: the pharmacokinetic model IEUBK, the InVS dose model, and an empirical relation (Lewin, 1999) between soil concentrations and BLLs. We tested the BLLs (percentage of children with a BLL > 100 mu g/l) that they predicted as well as threshold levels of soil pollution (200, 400, 500 ppm) for 71 situations for which the literature reports both environmental soil concentrations and BLLs in children aged 0-6 years. The tools' performance (sensitivity and specificity) was assessed by the rate of 'correct' (mass screening or not) decisions, judged retrospectively on the basis of measured BLLs, for different tolerated percentages of children with elevated BLLs. Results: Decision support systems based on soil pollution levels were not adequately protective. The IEUBK and (updated) InVS mechanistic exposure models were the most effective in this setting. Conclusion: Exposure models may provide decision support if sufficient data about environmental contamination and dietary intake are available. Absolute performance measurement nonetheless remains difficult, in view of the limitations of the input data.