The decrease in the exposure biomarker for lead (BPb)
levels in the studied group could be explained by
lower lead exposure due to improvements in environment
quality. The evolution of this environmental case
in Torreon Mexico is similar to that reported for Port
Pirie in South Australia. As reported by Kranz et al.
[18], in 1984 children had B-Pb concentrations with a
geometric mean of 20 μg/dl (range 1 - 46 μg/dl). Since
then, there has been a general downward trend to 9 μg/
dl (1 - 4639 μg/dl) in 2002, which corresponded to
environmental, nutritional, community and medical
interventions in population. Aging can also decrease
lead exposure by changes in children’s habits, such as
the normal abandon of mouth activities as children age
[19]. Also, an important part of the decline in B-Pb can
be explained by lead redistribution from blood to bone
and other hard tissues, as a result of the usual toxicokinetics
of lead [20]. It would be beneficial to study the
lead in bone concentrations in this group when the children
become adults.