Background
A recent review of biological monitoring results has shown that some gold room workers have been repeatedly exposed to elevated levels of heavy metals, such as arsenic, lead and mercury. Subsequent regulatory inspections identified that the control measures (e.g. ventilation) and atmospheric and biological monitoring programs, used to ensure heavy metal contaminants are at levels below exposure standards, are often inadequate and ineffective.
Summary of hazard
Gold room processes such as acid digestion, calcination, smelting and electrowinning generate fumes, dust and gases that contain hazardous contaminants (e.g. lead, mercury, arsenic).
Chronic exposure to lead may cause neurological and behavioural effects such as anxiety, weakness, headaches, tremors, excessive tiredness, depression and other indicators of nervous system damage. Women of child-bearing age have a much lower limit for blood lead levels (10 μg Pb/dL) to protect the foetuses of any current or future pregnancies.
Chronic exposure to mercury vapour primarily affects the central nervous system and kidneys. Systemic effects have also been reported after acute and chronic exposure to inorganic arsenic compounds. Elevated acute exposures to both inorganic arsenic and arsine has resulted in fatalities. In 2004, arsenic was classified as a known human carcinogen by the International Agency for Research on Cancer.
Contributory factors
- Lack of hazard identification in the early stage of the mineralisation study and analysis of ore body mineralogy.
- Inadequate or ineffective engineering controls [e.g. local extraction ventilation (LEV) systems].
- Inadequate atmospheric and biological monitoring programs.
- Safe work practices (SWPs) do not incorporate specific hygiene programs.
- Inadequate or ineffective selection and use of respiratory protective equipment (RPE).