An audit of biological monitoring of industrial lead workers by a UK laboratory over a 2-year period.
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 microg/dL (0.05-4.25 micromol/L), median 29 microg/dL (1.4 micromol/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 micro g/dL (0.05-3.58 micromol/L), median 7 microg/dL (0.34 micromol/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.


CONCLUSIONS
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.
Allen
K R
KR
Department of Clinical Biochemistry, Leeds Teaching Hospitals, Britannia House, Morley, Leeds LS27 0DQ, UK. keith.allen@leedsth.nhs.uk
Newton
K E
KE
D002617:Chemical Industry; D004784:Environmental Monitoring / Q000592:standards*; D005260:Female; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D007854:Lead / Q000032:analysis* / Q000097:blood; D008297:Male; D016273:Occupational Exposure / Q000032:analysis; D011524:Protoporphyrins / Q000032:analysis; D012737:Sex Factors; D013997:Time Factors; D006113:United Kingdom
D006454:Hemoglobins; D011524:Protoporphyrins; C017803:zinc protoporphyrin; D007854:Lead