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Occupational exposure to 4,4’-Methylenedianiline (MDA) may occur with workers who manufacture, process, or handle MDA or MDA-containing materials. MDA is used to produce di-isocyanate and polymer isocyanates used as polyurethane foams like those used for insulating mailing containers, rubber, resins, glue, and some dyes. This pale brown material with an ammonia-like odor liquid is easily inhaled or absorbed through the skin and has been known to cause liver damage in humans and animals.
Scope
Occupational exposure to MDA is possible through inhalation and skin contact during manufacturing, processing, and handling of the substance or MDA-containing materials. The compound has been detected in workplace air, in worker urine samples, and on skin patches worn by workers in certain industries. MDA has also been known to be released from polyurethane parts of dialysis equipment when sterilized with radiation or heat.
MDA exists in many similar forms, so employers remain diligent in assessing the potential for worker exposure. Workers in chemical laboratories, chemical processing plants, waste disposal sites, and polyurethane manufacturing or packaging are especially susceptible to MDA exposure. Workers in other industries may also have the potential for MDA exposure, including those that manufacture paint or epoxy, use tool and die equipment, or perform resin casting and molding operations.
The action level (AL) for MDA is 5 parts per billion (ppb), and the PEL is 10 ppb, which is an eight (8) hour time-weighted average (TWA). OSHA has also established an excursion limit (EL) for MDA, which is 100 parts per billion (ppb) on average over a 15-minute period.
Regulatory citations
- 29 CFR 1910.1050 (general industry) or 29 CFR 1926.60 (construction)
- 29 CFR 1904 — Recording and reporting occupational injuries and illnesses
- 29 CFR 1910 Subpart I — Personal Protective Equipment (PPE )
- 29 CFR 1910 Subpart N — Materials handling and storage
- 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
- Action limit (AL): The point at which a task or activity should be proactively changed to prevent an injury, illness, or other negative consequence.
- 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.
- Hazardous: Posing a health hazard, a physical hazard, or harm to people or the environment.
- Isocyanate : Raw material that makes up polyurethane products such as paint, epoxy, or foam. Isocyanates are considered potent respiratory allergens and research reveals between 5 and 20 percent of exposed workers can become sensitized to them.
- 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, an employee to MDA.
- 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 containing MDA.
- Ensure hazardous materials are properly inventoried and 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 or near misses to find root causes and implement corrective actions to prevent future occurrences.