Background: Medical surveillance of workers in the lead industry is
under the statutory control of the Control of Lead at Work Act (CLAW). Over the years
the CLAW regulations have been updated with a reduction in the suspension
concentration for blood lead and the introduction of an action limit. As a result of
these changes, an audit of blood lead measurement together with an evaluation of
haemoglobin and zinc protoporphyrin (ZPP) measurements, also requested as part of
surveillance, is required.
Methods: Results of measurements for blood lead, ZPP and haemoglobin in
lead-exposed workers in 58 industries within the UK were collected over a 2-year
period.
Results: For male workers, 8.8% of blood lead results [range 1-88 µg/dL
(0.05-4.25 µmol/L), median 29 µg/dL (1.4 µmol/L), n = 3010] were above the action
limit and 5.6% above the suspension limit set by CLAW. For female workers, 1.9% of
blood lead results [range 1-74 µg/dL (0.05-3.58 µmol/L), median 7 µg/dL (0.34
µmol/L), n = 161] were above the action limit. No significant correlation was found
between blood lead and haemoglobin in the male workers (rs =-0.04, P =
0.024) and only a slight negative correlation for the female workers (rs
=-0.25, P = 0.0016). ZPP showed an exponential relationship with blood lead in the
male workers with a wide scatter of results.
Conclusion: Haemoglobin and ZPP offer little towards the assessment of
lead exposure in industrial workers. Blood lead in accordance with the CLAW
regulations still offers the most appropriate means of industrial monitoring.
