The relationship between atmospheric lead concentrations and blood lead concentrations

Abstract

The relationship between ambient air lead concentrations (PbA) and blood lead concentrations (PbB) was investigated in 52 adult, ( non-occupationally exposed Maltese volunteers from 3 different localities (phase I); 39 adults from the same group were monitored over a period of one year (phase 11). Results from phase I showed no PbB differences arising from locality with respect to degree of urbanisation and proximity to heavy traffic. PbB in males was significantly higher than in females (p=1.12x1 0-5); in fact, sex was found to be a highly confounding variable in the relationships between PbB and haematological parameters, height, weight, occupation, residence address, car ownership and bread consumption. In addition, PbB was positively correlated with height, car ownership and degree of bread consumption (p<0.05). The subpopulation studied in Phase 11 had a mean annual PbB of 17.9 M9/dL; however, a third of the subjects exceeded 20 µg/dL, and were thus potentially exposed to harmful subclinical effects of lead. Urban PbA at peak traffic times was 1.6 µg/m3, whilst at the rural site, mean annual PbA was as low as 0.043 Mg/m 3. PbA was found to be related to traffic density by a non-linear relationship (R2=0.8835) which was influenced by sampling site characteristics. The lack of any PbA-PbB relationship was attributed to the fact that the air samples utilised could not account for the contribution of non inhalatory routes of PbA entry into the body (ingested dust or dust-contaminated food) as well as not being truly representative of the different PbA the subjects were in contact with during the day. However, PbA and PbB exhibited similar seasonal variations with a peak (1.4 Mg/m 3 and 24.8 M9/dL respectively) occuring in September 1994, which may have been caused by increased lead exposure due to both meteorological and anthropological factors. Petrol lead, which is responsible for most of the ambient PbA, was estimated to be contributing 11.6-23.2% to PbB, an increase of 1.6 times with respect to 1983/84.