Smaller Geographic Area Analysis Unsuppressed ZIP Codes and Census Tracts, 2018
For reported BLL results for children < 6 years old tested in 2018, ArcGIS geocoding software was used to assign test results to postal ZIP codes and determine the percentage of reported test results in the ZIP codes that were ≥ 4.5 mcg/dL. The California Health and Human Services Agency's Data De-Identification Guidelines (DDGs) were then applied to the results for each ZIP code to determine whether findings could be reported. BLL results for children < 6 years old tested in 2018 were reported to California Department of Public Health (CDPH) from 1,470 of California's 1,721 non-P.O. Box ZIP codes. For ZIP Codes without reported results there may be no at-risk children, no testing, or no reported results.
After applying the DDGs, data could only be reported for 107 (7.3 percent) of the 1,470 ZIP codes with reported BLLs. Data for unsuppressed ZIP codes is shown in Table 7, ranked by the percentage of reported BLLs ≥ 4.5 mcg/dL. Percentages range from 20.4 percent in ZIP code 95821 in the city of Sacramento to 0.45 percent in ZIP code 92335 in the city of Fontana. Because the DDG's required suppression of data for 93.5 percent of California ZIP codes with reported BLLs, this publicly reportable data is of limited use for identifying geographic areas with high percentages of children with elevated BLLs.
AB 1316 mandates reporting of census tract information to the greatest extent possible. A similar analysis was conducted to determine the percentage of children (< 6 years old) in each census tract with BLLs ≥ 4.5 mcg/dL. After applying the DDGs, there was no census tract for which results could be reported.
While there are limitations on the level of detail that can be publicly reported without risking identification of individual children, state and local lead programs can use this information internally to guide programmatic decision making, and to develop approaches to preventing lead exposure and identifying children with elevated BLLs.