Inorganic lead is a malleable, blue-gray, heavy metal that occurs naturally in the earth’s crust. Lead was one of the first metals used by humans and consequently the cause of the first recorded occupational disease (lead colic in a 4th Century BC metal worker). When absorbed, it can be stored in human bones, blood and tissues. And, as we age, bones demineralize and the internal exposures may increase as a result of larger releases of lead from the bone tissue.
Workers are primarily exposed to lead by breathing in dust particles containing lead, lead compounds that get on the skin or contaminate clothing, and lead compounds that are ingested. They can also be exposed by breathing in lead fumes produced during processing when metal is being heated or soldered. Lead dust can also settle on food, water, and other objects. If lead dust gets on clothes, a worker could track it to the home which may expose family members. Lead poisoning has occurred in children whose parent accidentally brought home lead dust on clothing.
Lead Exposure Levels
The Occupational Safety & Health Administration (OSHA) has set forth regulatory requirements for preventing and controlling workplace lead hazards. Under OSHA, employers are required to protect workers from inorganic lead exposure under lead standards covering general industry (1910.1025), shipyards (1915.1025), and construction (1926.62). Per these standards, the Permissible Exposure Limit (PEL) for lead is no greater than 50 micrograms per cubic meter (µg/m3) averaged over an eight-hour period.
The National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL) for lead is also 50 µg/m3of air averaged over an eight hour period. NIOSH indicates that some studies suggest that the current OSHA PEL and NIOSH REL may be too high to protect against certain health effects, such as cognitive dysfunction and adverse reproductive outcomes. Therefore, it is important to eliminate or reduce potential exposures below these levels.
What Industries Are at Risk?
Lead is an ingredient in thousands of products widely used throughout industry – including lead-based paints, lead solder, electrical fittings and conduits, tank linings, plumbing fixtures, and numerous metal alloys. Although many uses of lead have been banned, lead-based paint continues to be used in general construction and on bridges, railways, ships, and other steel structures because of its rust and corrosion-inhibiting properties. And in homes and schools, significant lead exposures can also occur when paint is removed from surfaces previously covered with lead-based paint – which was banned for residential use in 1978.
Additional industrial risks include renovation/repair of buildings after a major storm or hurricane; bridge reconstruction workers (old paint may contain lead); firing range instructors, gunsmiths and police officers (ammunition contains lead); and recyclers of metal, electronics and batteries (may contain lead).
Evaluating Lead Hazards in the Workplace
In evaluating potential lead exposure, employers typically begin with a workplace lead assessment performed by an occupational safety and health professional, such as a Certified Industrial Hygienist (CIH). The workplace assessment usually starts with a tour of the facility/site to identify specific work activities that expose employees to lead hazards. These may include, for example, torch cutting on structures containing lead-based paint; dust generation from lead soil contamination; and renovation or demolition of buildings/schools containing lead-based paint. Additionally, historical information of the property may provide insights into past and present lead exposure.
Once suspect lead areas are identified, the amount of lead on surfaces/ materials can be accurately determined through testing – using field sampling test kits and/or wipe sampling – which requires submittal to a qualified lab for analysis. During work activities, the CIH may conduct air sampling in the worker’s breathing zone to determine if airborne lead exposures exceed PEL or REL.
Exposure Control Measures
The most effective way to prevent exposure to a hazardous material such as lead is through elimination or substitution with viable, less toxic alternatives. Generally, this is the preferred choice – followed by engineering controls, administrative controls, work-practice controls, and personal protective equipment (PPE). OSHA requires employers to use engineering controls and work practices, where feasible, to reduce worker exposure.
Engineering controls include isolating the exposure source, or use of local exhaust ventilation to minimize exposure to lead. Administrative controls involve limiting the amount of time a worker performs work. Work practice controls – including good housekeeping methods to prevent surface contamination; hygiene facilities; and protocols to protect workers from ingesting and taking home lead – are also necessary to prevent exposure to lead. When lead hazards cannot be engineered out and safe work practices/administrative controls are ineffective, PPE is required in accordance with 29 CFR 1910.134.
In addition, air/wipe sampling and blood/urine sampling (medical surveillance) should be performed to determine the effectiveness of controls and PPE. This may entail prioritizing the job functions that pose the greatest risk of overexposure to lead during an eight-hour workday within a 40-hour work week.
HETI…Helping Evaluate and Control Lead Hazards
HETI can assist facilities facing the challenges of lead exposure in the workplace. Our experienced Certified Industrial Hygienists are available to help employers comply with OSHA/NIOSH lead standards – through hazard recognition, monitoring, and control development. Whether the need is for a written compliance program, training, workplace exposure assessments, or simply addressing questions on compliance, we are here to help reduce the risk.
References:
Occupational Safety and Health Administration (OSHA), Department of Labor, OSHA Fact Sheet, 9/2005: Protecting workers from lead hazards
National Institute for Safety and Health (NIOSH), Workplace Safety and Health Topics, Lead, June 2018: (www.cdc.gov/niosh/topics/lead/publications)
OSHA, Safety and Health Topics, Lead Resources: (www.osha.gov/lead/resources)
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