Figure 14: Percent of Children With Blood Lead Levels ≥ 10 mcg/dL at Age Two Years by Blood Lead Level at Age One Year; 1998 – 2004 Birth Cohorts (Blood Lead Test Data Through 2007), New York State Excluding New York City

In response to growing scientific concern about the harmful effects of blood lead levels below 10 mcg/dL, a special analysis was conducted examining "serial" blood lead test results among children who were tested for lead at multiple ages, in accordance with New York State blood lead testing requirements.

Figure 14 shows the results of this analysis. Among children born in 2004 who were tested for lead at both ages one and two years, 2 percent of those with a BLL below 10 mcg/dL at age one year had a BLL ≥ 10 mcg/dL when tested again at age two years. However, within this group, 8.5 percent of those whose BLL was 5 - 9 mcg/dL at age one year had a BLL of 10 mcg/dL or higher when tested again at age two years, compared to 1.3 percent of children with whose BLL was below 5 mcg/dL at age one year. Children with a BLL of 5 - 9 mcg/dL at age one year were over six times more likely to have a BLL ≥ 10 mcg/dL at age two years than those with a BLL < 5 mcg/dL at age one year. This analysis was repeated for all birth cohorts 1998 – 2004 (testing data through 2007), with the same general finding. In addition, the percent of children with a BLL of 5 - 9 mcg/dL at age one year who went on to have a BLL ≥ 10 mcg/dL at age two years declined every year, mirroring the general statewide decline in childhood BLLs..

These findings underscore the importance of obtaining a second blood lead test at age two years, even when the first blood lead screening test result at age one year is below 10 mcg/dL. The importance of repeated blood lead testing is especially emphasized for children whose first blood lead test result is approaching 10 mcg/dL (i.e., 5 - 9 mcg/dL).

Birth Year Percent of Children with initial test < 5 mcg/dL Percent of Children with initial test 5-9 mcg/L
1998 3.1 13.5
1999 2.3 12.4
2000 2.4 12.3
2001 2.0 11.4
2002 2.0 11.3
2003 1.5 9.0
2004 1.3 8.5