Adverse haematological outcome and environmental lead poisoning

The South-eastern Area (SA) of the Municipality of La Spezia (Liguria Region, Italy) is characterised by a heavy environmental lead (Pb) contamination, chiefly due to the emissions of a Pb-processing plant in operation since 1930. In order to assess the risk of Pb poisoning of residents of SA, and to estimate the degree of association between the blood Pb level (BLL) and haematocrit % (HCT), intended as a biomarker of early haematological dysfunction, we reanalysed data of 785 individuals collected in 1992 as a part of a larger national biological monitoring project. Multiple normal regression modelling was applied to estimate the role of residence on log-transformed BLL, and Median Ratio (MR) was used as an index of effect. The same statistical modelling was also applied to reveal the relationship between HCT and BLL. Allowing for several confounders (including occupational exposure to Pb), residents of SA showed a 14% increase (MR=1.14, 95% IC=1.06-1.23%) in the median BLL value compared to people living outside SA. The excess reached 27% (MR=1.27, 95% IC=1.14-1.41%) after 30 years of residence. Parallel results were also obtained in a subgroup composed only of pupils (<18 years, non-smokers, non-drinkers). Finally, regression analysis highlighted a statistically significant parabolic trend in HCT in relation to BLL. The non-linear dose-response relationship, which attests to an adverse effect on the erythrocytic function of BLLs at least over 17.00 microg/dl, is in agreement with the findings of other authors and consistent with the results of an excess occurrence of self-reported anaemia obtained from a previous comparative survey carried out on the same population.