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Abstract
In many urban contexts, non-dietary Pb exposure from street dusts may add to the overall
exposure burden, and the presence of high total Pb content is well documented in urban
street dust from across the globe. Given the increasing recognition of the potential
adverse health effects from both the quantity and the chemical and physical composition
of the inhaled fraction, and the recognition that it is the soluble fraction rather
than the total element content that has more direct links to health effects, attention
has focused in this study on the human health risks via this exposure pathway. In
order to investigate the environmental exposure to Pb from the inhalation of urban
street dusts, a newly developed in vitro simulated epithelium lung fluid (SELF) has
been applied to the <10μm fraction of urban street dusts. In this context, 21 urban
street dust samples, across five UK cities, were selected based on their high pseudo-total
Pb content. The work revealed that inhalation bioaccessibility, and hence inhalation
dose, varied across the cities but was generally found to be low (<10%). Indeed, the
lung bioaccessibility was far lower (% lung bioaccessibility ranged from 1.2 to 8.8)
than is currently applied in two of the most commonly employed risk assessment models
i.e. the Integrated Exposure Uptake Biokinetic model (IEUBK, USA) and the Contaminated
Land Exposure Assessment model (CLEA, UK). The estimated inhalation dose (for adults)
calculated from the PM10 bioaccessibility ranged from 7ngkg-1BWday-1 (Edinburgh) to
1.3ngkg-1BWday-1 (Liverpool). The results indicate a low potential inhalation bioaccessibility
for Pb in these urban street dust samples when modelled using the neutral pH conditions
of the SELF.