Established by order of the regional prefect in 1992, the Ile-de-France Childhood Lead Poisoning Surveillance System (Sssiilf) brings together all regional partners involved in screening and/or the care of children with lead poisoning to collect and analyze the results of all blood lead level tests performed on children in the Ile-de-France region. Each prescribing physician is required to complete a standardized information form for any request for laboratory testing related to suspected lead poisoning in a child or to the follow-up of confirmed poisoning. The information requested from the prescribing physician concerns the child, the reasons for the prescription, and, if applicable, any medical or environmental interventions carried out since the previous blood lead level test. The laboratory performing the prescribed tests completes the document by entering the results of the blood tests, then returns it to the prescribing physician and sends a copy to the Paris Poison Control Center. When necessary, the center contacts the prescribing physician to complete the form; it enters the information contained therein into a computer system. The results presented here are based on an analysis of data collected during the first 10 years of the Sssiilf’s operation. It should be noted that this form will be replaced in February 2004 by the mandatory reporting form for childhood lead poisoning. At the regional level, screening activities are relatively stable from one year to the next, but they vary significantly across departments and municipalities. Seine-Saint-Denis and Paris account for by far the largest share of screening activity in the Île-de-France region over the entire period (46% and 38%, respectively). The municipalities of Aubervilliers, Pantin, and Saint-Denis alone account for 79% of screening activity in Seine-Saint-Denis. In Paris, screening activity is concentrated in the northern and eastern arrondissements of the capital. The proportion of children tested appears low, except in the most actively involved municipalities. In Aubervilliers, Pantin, and Saint-Denis, 48%, 25%, and 19% of children living in these municipalities, respectively, are tested before the age of 6. For the entire Île-de-France region, only 1.8% of children living in the region are tested before age 6. This disparity can be explained in part by the fact that substandard housing, the primary risk in the Île-de-France region, is unevenly distributed across the region. It is also due to the varying proximity of maternal and child health services to the population and the differing levels of involvement of these services and other screening stakeholders. Screening activities are in fact overwhelmingly carried out by maternal and child health services, followed by a few hospital pediatric departments. The participation of general practitioners and private pediatricians is negligible. The median age at screening is 2 years and 5 months. It decreased by 9 months over the period. Initial screenings primarily involve children whose parents are of sub-Saharan origin, not because of this geographic origin, but because they have multiple risk factors. A home built before 1948 and in poor condition is the primary criterion for referring a child for an initial screening test. Living in a home built before 1948 with no indication of deterioration or recent renovations is the next most common factor. The presence of pica behavior or other children with lead poisoning in the child’s environment is also frequently mentioned. Initial screening tests almost always included a blood lead level measurement (99%). The number of children with blood lead levels of 100 μg/L or higher at their first screening test declined sharply over the period. Indeed, there was a significant decrease in the yield of initial screening: at the start of the period, more than 60% of blood lead levels were above 100 μg/L; this percentage fell to 10.3% by the end of the period. The median blood lead level at the initial screening dropped from 129 μg/L in 1992 to 55 μg/L in 2001. A combination of factors likely contributed to this trend: the reduction in lead exposure from atmospheric and dietary sources, as well as the effects of the prevention programs implemented. One should be cautious about concluding that the proportion of children with lead poisoning in the Île-de-France region has decreased by the same proportion, since fewer than 2% of children in the region are tested before age 6 and screening activities and major prevention efforts have remained concentrated primarily in the same areas throughout the period. Among the children tested whose mothers are from Sub-Saharan Africa, 36% have blood lead levels of 100 μg/L or higher. This percentage ranges from 21% to 9% for children whose mothers are from other continents. These differences can be explained by disparities among populations of different origins regarding housing-related risk factors. Due to their higher risk factors, children from Sub-Saharan Africa, North Africa, and the Eastern Mediterranean are tested more frequently. They thus account for 87% of children with blood lead levels of 100 μg/L or higher at the initial screening. The risk factors with the highest positive predictive value are: the presence of other lead-exposed children in the immediate environment, pica behavior, and substandard housing prior to 1948. 65% of children had only one blood lead level test, but some children underwent numerous tests, up to 25. The percentage of children undergoing at least one follow-up test increases with the blood lead level at the initial screening. Only 25% of children with a blood lead level below 100 μg/L at the initial screening were re-screened, compared to nearly 70% of children with a blood lead level of 100 μg/L or higher. It is observed that the blood lead levels of the vast majority of re-screened children decrease. However, regardless of the initial blood lead level category and regardless of the time interval between the first and last blood lead level tests, a significant percentage of children “remain” in pathological blood lead level categories, and some even see their blood lead levels worsen. This worsening is also observed among those who had a blood lead level below 100 μg/L at the first examination. This finding justifies the recommendation to continue monitoring children with risk factors, regardless of the result of the initial blood lead level test. The low response rate regarding environmental interventions makes it difficult to analyze the impact of legislative and regulatory measures implemented since 1998. Information provided to treating physicians regarding actions implemented by the administration for reported children needs to be improved. More than 1,784 courses of chelation therapy were administered to 528 children during the period. The number of children undergoing chelation therapy per year is decreasing, in line with the decrease in the number of children tested with elevated blood lead levels. Calcium disodium EDTA*, the most widely used product until 1996, was gradually replaced by DMSA* starting in 1997. In total, 6,935 children were tested with blood lead levels of 100 μg/L or higher during the 1992–2001 period in the Île-de-France region (including 6,453 under the age of 6), with the annual number dropping from 1,248 in 1992 to 336 in 2001. The average annual incidence rate of 71.3 per 100,000 children under 6 years of age is comparable to the prevalence rate obtained in the 1996 survey conducted by INSERM and the National Public Health Network (RNSP), which reported that 2.1% of children aged 1 to 6 in France had blood lead levels exceeding 100 μg/L (i.e., 2,100 cases per 100,000 children). Even taking into account the different meanings of incidence (new cases) and prevalence (cases present at a given time), it is surprising to note that there is a factor of nearly 30 between these two figures. Based on the estimate provided by Inserm, lead poisoning screening in the Île-de-France region would therefore fall far short of identifying all children with lead poisoning. (R.A.)