In comparison with the number of cases reported in boys (Table 2)
with noticeably decreasing figures, the same rate for girls was on the
increase (Table 2). The highest rates prevail in large cities lacking
recreational and green areas. The lowest rates are observed in rural
districts, where the exposure to hazardous environmental factors is
lower.
The contrastive analysis carried out for particular districts shows
that the spatial distribution of the incidence rate in boys is similar to
that of the general population. This rule, however, does not apply to
girls.
To study the relationship between the number of cases and the
level of pollution, the correlation coefficient for incidence and
pollution was calculated for each analyzed year. The obtained
coefficients in the case of lead pollution indicate a lack of correlation
in the years 1995 (0.0) and 1996 (−0.3) as well as weak correlation in
the years 1997 (0.2), 1998 (0.1) and 1999 (0.1).