Case Study: Heavy Metal Biomonitoring

Case Studies · Case Studies overview

Anonymised case study of a CLAW lead and cadmium biomonitoring programme at a UK secondary metals recovery plant processing mixed lead-acid battery and electronic-scrap feedstock.

Workplace scenario

Secondary metals recovery plant, ~50 production workers across feed preparation, smelting, refining and dispatch. Feedstock mix produces both lead and cadmium exposure. Existing CLAW programme in place for lead; cadmium added following an internal HSE inspection action.

Exposure concern

CLAW blood-lead surveillance functioning. Cadmium had been treated as a 'lead-plant minor contaminant' but feedstock data showed Cd content rising over recent years; urinary cadmium and β2-microglobulin added as discretionary biomarkers.

Monitoring approach

Blood-lead every 3 months for CLAW (action level 50 µg/dl women / 60 µg/dl other workers; suspension 60/70 µg/dl). Urinary cadmium random spot, twice per year, paired with β2-microglobulin. ICP-MS at UKAS lab. Smoking status recorded.

Interpretation themes

Blood-lead cohort GM ~35 µg/dl, stable across campaigns, with two individuals above action level traced to baghouse maintenance task. Urinary cadmium GM ~3 µg/g creatinine in non-smokers, ~7 µg/g creatinine in smokers — above ACGIH BEI for the smoker subgroup. β2-microglobulin all within reference range.

Control improvements and lessons learned

Baghouse maintenance moved to supplied-air respirators; smoking-cessation support offered through occupational health; cadmium feedstock segregation reviewed. Lessons: cadmium body burden was not driven by current plant emissions alone — historical exposure and smoking interacted to produce results above BEI.