Environmental lead exposure in European children - are the problems solved yet?

For a long time, lead exposure in children was a major problem in European countries. However, time-trend studies in Sweden, Poland and the Czech Republic have shown that the exposure has decreased dramatically; e.g., a study in about 4,000 Swedish children (mostly age 7-8), the geometric mean (GM) was about 60 microg/L in the late 1970s, while in 2009 it was only 10 microg/L, mainly as a result of the elimination of petrol lead.  In 2007-8, the variation of B-Pb between 433 children (age 6-14) in six European cities (in Croatia, Czech Republic, Poland, Slovakia, Slovenia, and Sweden) was surprisingly small; the GM ranged 13-19 (range in individuals 6-47) microg/L. However, there are still hot-spots around industries.  However, at the same time, information during the last few years has indicated that effects of lead on the central nervous system of children may occur at much lower exposure than previously known. Hence, in a study of 860 children, who had been sampled at age 7-8, and whose school merits were recorded at age 16, there was a significant effect even at B-Pb <50 microg/L.  It has long been known that there is a large inter-individual variation in susceptibility to lead. One possible explanation is a genetic predisposition. We have examined the modification by polymorphisms in the (delta)-aminolevulinic acid dehydratase (ALAD) gene of the relationship between cognitive function and B-Pb in Polish children, and found that there is a significant effect. The ALAD protein is an enzyme ssusceptible to lead inhibition, and is a major binding site for lead in blood and tissues, which might indicate a differential sequestration of lead, making it less available for other sites.