Study of welding trainees reveals need for proper ventilation, PPE

November 14, 2025

Montreal — A recent study of apprentice welders revealed a “significant increase” in metal levels in urine, nail and hair samples taken over the duration of their three-module training program.

A team from the Canadian research organization IRSST and the University of Montreal followed 116 apprentice welders to examine their exposure levels to welding fumes and their metallic components.

“Heavy metal poisoning (toxicity) is the result of exposure to heavy metals like lead, mercury and arsenic,” the Cleveland Clinic says. “Heavy metals bind to parts of your cells that prevent your organs from doing their job. Symptoms of heavy metal poisoning can be life-threatening, and they can cause irreversible damage.”

Researchers determined that concentrations of iron, manganese, nickel and chromium “increased steadily over time.”

Other findings:

• Arsenic levels increased in fingernails and hair (but not in toenails).

• Cobalt concentrations increased in fingernails and toenails (but not in hair).

• Levels of iron, manganese and nickel in urine increased in the first module of the apprentice program but not in the final two modules.

• Manganese concentrations exceed American Conference of Governmental Industrial Hygienists guidelines – “a concerning factor for neurological health.”

“This study highlights the importance of better regulating the prevention of exposure to welding fumes,” study co-author Michèle Bouchard, of the University of Montreal, said in a press release. “It is essential to optimize ventilation practices and personal protective equipment to protect the health of workers.”