New inorganic lead-monitoring guidelines

Issue: BCMJ, vol. 58 , No. 5 , June 2016 , Pages 275,287 WorkSafeBC

Lead (Pb) is the quintessential heavy metal with toxic properties that have been recognized for centuries. It’s a naturally occurring, nonessential element with well-defined dose-toxic effect relationships. Adverse health effects may start with blood lead levels (BLL) as low as 0.48 µmol/L (10 µg/dL)* in adults. The 95th percentile for BLL for Canadian adults is approximately 0.2 to 0.3 µmol/L. Adverse health effects associated with elevated lead exposure include hypertension and anemia, as well as renal, gastrointestinal, reproductive, and central and peripheral nervous system dysfunction. The International Agency for Research on Cancer has deemed lead a probable carcinogen.

Inorganic lead is absorbed by inhalation or ingestion. Signs and symptoms of lead exposure vary with the dose and duration of exposure. They are typically nonspecific and can include fatigue, myalgia, arthralgia, irritability, lethargy, abdominal discomfort or pain, tremors, headaches, constipation, and difficulty concentrating. More extreme exposures can result in encephalopathy with seizures, altered consciousness, coma, and death. Enquiring about workplace activity and exposure can identify lead exposure as a possible contributing factor. For additional information on lead toxicity and management, see the suggested reading.

Lead exposure in the workplace

Lead exposure still occurs in many workplaces in BC, and every year WorkSafeBC adjudicates claims for exposure and toxicity. Exposure situations vary from law enforcement officers doing target practice, to workers at battery recycling facilities or radiator repair shops, welders dismantling lead painted bridges, metal refinery workers, grinders of fishing lead lures, and others. WorkSafeBC requires that employers have an exposure control program for lead-exposed workers.

Exposure control programs typically include biological monitoring for lead by measuring BLL. WorkSafeBC guidelines for BLL monitoring were summarized in a prior article in the BCMJ (2009;51:388). The guidelines were based on the American Occupational Safety and Health Administration standards first enacted into law in 1978 for general industry. Many clinicians and researchers in the field of occupational medicine have advocated for a review of the older standards of practice because they are not considered to be sufficiently protective for workers with occupational lead exposure. Newer recommendations have been proposed to rectify this situation and better protect the health of workers. In response to these changes, WorkSafeBC is also updating its guidelines. These newer guidelines are summarized in the Table.

Further information

If you are concerned about the evaluation of a worker’s exposure or BLL results, please contact a medical advisor in your nearest WorkSafeBC office.
—Sami Youakim, MDCM, MSc, FRCP
WorkSafeBC Medical Advisor

*In the past, BLL was reported in µg/dL, but now it is reported in µmol/L (1 µmol/L is approximately 20 µg/dL).

Suggested reading

Agency for Toxic Substances and Disease Registry. Case studies in environmental medicine, lead toxicity. Accessed 19 April 2016. www.atsdr.cdc.gov/csem/lead/docs/lead.pdf.

Friedman LS, Simmons LH, Goldman RH, et al. Case records of the Massachusetts General Hospital. Case 12-2014. A 59-year-old man with fatigue, abdominal pain, anemia, and abnormal liver function. N Engl J Med 2014;370:1542-1550.

Warniment C, Tsang K, Galazka SS. Lead poisoning in children. Am Fam Phys 2010;81:751-757.

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This article is the opinion of WorkSafeBC and has not been peer reviewed by the BCMJ Editorial Board.

Sami Youakim, MD, MSc, FRCP. New inorganic lead-monitoring guidelines. BCMJ, Vol. 58, No. 5, June, 2016, Page(s) 275,287 - WorkSafeBC.



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