James Sacco
Department of Pharmacy
Faculty of Medicine & Surgery
University of Malta

ABSTRACT
(presented at the Medical School Conference 1999 and the Seminar on Atmospheric Pollution 1999)

The relationship between ambient air lead concentrations (PbA) and blood lead concentrations (PbB) was investigated in 52 adult, non-occupationally-exposed Maltese subjects from 3 localities with different degrees of urbanisation and traffic density (Phase I); subsequently, 39 adults from the same group were monitored over a period of one year (Phase II). Results from Phase I showed no PbB differences arising from locality with respect to degree of urbanisation and proximity to heavy traffic. Significantly higher PbB were observed in drivers and bread consumers. Urban PbA at peak traffic times was 1.6 g/m3, whilst at the rural site, mean annual PbA was found to be 0.043 g/m3. PbA was found to be related to traffic density by a non-linear relationship (R2=0.8835) which was influenced by sampling site features such as road morphology and height of adjacent buildings.

The lack of any detectable PbA-PbB relationship was attributed to the fact that the air samples could not account for the contribution of non-inhalatory routes of PbA entry into the body (ingested dust and/or dust-contaminated food) as well as not being truly representative of the different PbA environments the subjects were exposed to during the day. However, PbA and PbB exhibited similar seasonal variations with a peak occurring in September, 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 over a period of ten years.