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Mercury is likely to be found in medical facilities or in laboratories but may also be in thermostats, gauges or valves, electrical switches, some fluorescent light bulbs, or in chemical or pharmaceutical manufacturing processes. You may also find mercury in heat transfer processes, certain catalysts, or lubricating oils, as well as dental fixtures, circuitry for athletic equipment and toys, and in clock pendulums.
This silver-gray liquid is especially dangerous when it contacts the air and vaporizes, increasing worker exposure. It can also easily spread, so it may be absorbed through the skin if protective measures aren’t taken. Precautions must be taken to avoid contamination on shoes, clothing, and objects that may be transferred to additional parts of the workplace or to a worker’s home.
Scope
Occupational exposure to mercury is possible through inhalation and skin contact and, in rare cases, through accidental ingestion. The presence of mercury is in most every industry with most workers having potential exposure. Maintenance, housekeeping, research and development, laboratories, offices, manufacturing, and shipping and receiving are especially susceptible to potential mercury exposure. Consuming large quantities of fish, seafood, and rice also exposes individuals to mercury.
The behavior of mercury can also contribute to the level of employee exposure. Exposure to air and sources of heat can increase the rate of vaporization and increase the potential for inhalation by employees, which can result in damage to the nervous system and kidneys. Industrial hygienists can assess, sample, and document mercury sources in the workplace and will determine where mercury spill kits or other protective measures are necessary for employee protection.
The ceiling concentration for mercury is 1.0 mg/10m3 for general industry with a permissible exposure limit (PEL) of 0.01 mg/m3 for construction and maritime as an eight (8)-hour time-weighted average (TWA).
Regulatory citations
- 29 CFR 1904 — Recording and reporting occupational injuries and illnesses
- 29 CFR 1910 Subpart I — Personal Protective Equipment (PPE )
- 29 CFR 1910.1000, Table Z-2 – Acceptable ceiling concentration for mercury
- 29 CFR 1910.1020 — Access to employee exposure and medical records
- 29 CFR 1910.1200 — Hazard communication
- 29 USC 654 — General duty clause of the OSH Act
Key definitions
- Ceiling concentration limit: The maximum concentration of a toxic substance to which a person can be exposed at any given time.
- Exposure: Subjecting a worker to a hazardous drug by any route of entry, such as inhalation, ingestion, skin contact, or absorption. Exposure includes potential (e.g., accidental or possible) exposure.
- Industrial hygienist: A person trained in the science of anticipating, identifying, analyzing, and controlling environmental factors in the workplace that may negatively impact worker safety and health.
- Permissible exposure limit (PEL): The legal regulatory limit of a substance that a worker can be exposed to without adverse health effects.
- Time-weighted average (TWA): A calculation of a worker’s average exposure to a hazardous material or substance over a given period of time, typically 8 hours.
Summary of requirements
- Conduct hazard assessments to identify operations or activities that may expose, or potentially expose, employees to mercury.
- Consult with industrial hygienists or other occupational health and safety professionals for guidance, as necessary.
- Develop an exposure control plan to ensure workers are protected from overexposure.
- Implement procedures for safe handling, disposal, and inspection of facilities, equipment, and tools used for processes involving mercury.
- Perform medical surveillance for exposed employees.
- Ensure hazardous materials are properly inventoried, mercury-containing equipment is labeled, and that safety data sheets (SDSs) are readily accessible for workers.
- Train workers in chemical and material handling hazards and required protective measures.
- Investigate any worker incidents, spills, or near misses to find root causes and implement corrective actions to prevent future occurrences.