Dichloromethane technical fact sheet
Dichloromethane, also known as methylene chloride, is a volatile, colourless, non-flammable liquid with a sweet ether-like odour. Adequate controls for the proper use, handling and storage of Dichloromethane reduces the risk of hazardous exposures and illness in the workplace.
The NSW Work Health and Safety Roadmap aims to achieve a 50% reduction in serious injuries and illnesses by 2022, including a 30% reduction in exposures to priority hazardous chemicals and materials. An initial list of 100 priority chemicals was developed based on national and international sources. This list was further refined using the following criteria: toxicity rating, exposure potential, estimated quantities used and potential number of workers using these chemicals. Dichloromethane ranked sixth based on these criteria.
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Sources of exposure
Dichloromethane is used as a solvent in paint removers and as a degreaser. It is used in metal cleaning, as a solvent in the production of polycarbonate resins, in film processing and in ink formulations. Its volatility has led to its use as a blowing agent for polyurethane foams. It is also used in the food industry as an extraction solvent.
When in contact with hot surfaces and open flames, dichloromethane can be decomposed and emit highly toxic fumes of phosgene and chlorine. Dichloromethane is rapidly absorbed following inhalation, skin absorption, eye contact and ingestion.
Dichloromethane is first metabolised to carbon monoxide. This can result in elevated levels of Carboxyhemoglobin (COHb) and potentially lead to carbon monoxide poisoning. The combined effect of smoking and exposure to dichloromethane can produce an additive increase in COHb levels.
Brief exposure to dichloromethane can cause eye and skin irritation and prolonged skin exposure can cause severe chemical burns. Dichloromethane can cross the blood-brain barrier and can result in central nervous system depression with symptoms like drowsiness or dizziness. When inhaled, dichloromethane vapours may cause severe irritation of the respiratory system which can cause a build-up of fluid in the lung (pulmonary oedema), leading to unconsciousness and death. Dichloromethane may also aggravate existing heart conditions and make the symptoms of angina (chest pains) worse.
Prolonged or repeated skin contact can result in dichloromethane dissolving some of the fatty tissues in skin, resulting in dermatitis. Long term exposure at high levels may also damage the liver and brain. Dichloromethane is a neurotoxin and is suspected of causing cancer.
Labelling and Safety data sheets
Manufacturers and importers of dichloromethane need to ensure that hazardous chemicals are labelled and safety data sheets (SDS) are prepared and provided (cl.330 and 335 Work Health and Safety Regulation 2017).
Suppliers of a hazardous chemical to a workplace must provide current SDS (cl.339).
Persons Conducting a Business or Undertaking (PCBUs) must correctly label hazardous chemicals used, handled or stored at the workplace, including containers and pipework (cl. 341,342,343). The PCBU must also obtain a copy of the SDS and make it readily accessible to workers involved in using, handling or storing the hazardous chemical at the workplace (cl. 344).
Workplace exposure standards and air monitoring
According to the Work Health and Safety Regulation 2017, businesses must ensure that workers are not exposed to airborne chemicals above the workplace exposure standard. Dichloromethane has a workplace exposure standard of 50 ppm or 174 mg/m3 averaged over eight hours (time weighted average). Risks to health and safety from exposures to hazardous chemicals must, so far as is reasonably practicable, be eliminated (cl. 35). PCBUs must ensure that no person at the workplace is exposed to a substance above its exposure standard (cl. 49) and must reduce exposures so far as is reasonably practicable.
PCBUs must undertake exposure (air) monitoring for substances with an exposure standard if they are not certain (on reasonable grounds) as to whether the exposure standard is exceeded (cl. 50). Adjustments to the exposure standards are made for extended work shifts, taking into account the longer daily exposure. Air monitoring results must be readily available to workers and records of results kept for 30 years (cl. 50).
A PCBU must review any control measures implemented if a workplace exposure standard for a hazardous chemical has been exceeded (cl. 352).
PCBUs are required to provide health monitoring to workers if there is a significant risk to the worker’s health because of exposure to a hazardous chemical listed in schedule 14 of the Work Health and Safety Regulation 2017. Dichloromethane is not listed in schedule 14, however there remains a requirement to provide health monitoring if there is a significant risk to the worker, and there are valid techniques to detect effects on workers’ health (cl. 368).
In relation to health monitoring, PCBU (cl. 369 to 378) duties include:
- informing workers of the requirements for health monitoring
- using a registered medical practitioner with experience in health monitoring
- providing details to the medical practitioner
- obtaining a copy of the health monitoring report
- providing a copy of the health monitoring report to SafeWork NSW if the worker has developed a disease or injury and/or the report contains any recommendations on remedial measures at the workplace keeping records of health monitoring for 30 years.
Where risks to health and safety cannot be eliminated the hierarchy of controls must be applied in accordance with cl. 36 of the Work Health and Safety Regulation 2017 to minimise risks.
- Eliminate the use of dichloromethane if reasonably practicable.
- Employ engineering controls to reduce fugitive emissions during transfers between closed systems.
- Where dichloromethane is not used in a closed system (such as laboratories) or is present as a contaminant of workplace air (such as car repair shops), good local exhaust ventilation should be ensured.
- Avoid inhalation, skin and eye contact by wearing appropriate respiratory protection along with chemical-resistant gloves and goggles and other personal protective equipment (PPE) deemed necessary.
- Instruct and train workers in the correct fitting, use and maintenance of PPE.
- Follow instructions and controls outlined in SDS and product labels.
PCBUs must provide suitable information, training, instruction and supervision to workers using, storing and handling hazardous chemicals regarding the nature of the work, risks and the controls implemented (cl. 39 and 379).
PCBUs with duties under the Work Health and Safety Regulation 2017 must review and revise control measures, as necessary, to maintain a work environment so far as is reasonably practicable, that is without risk to health or safety (cl. 38).
More information is contained in:
- the dichloromethane containing product's SDS
- NSW codes of practice:
- Safe Work Australia guidance material:
- Workplace Exposure Standards for Airborne Contaminants
- Guidance on the Interpretation of Workplace Exposure Standards for airborne contaminants
- Health Monitoring for Exposure to Hazardous Chemicals - Guide for persons conducting a business or undertaking
- Health Monitoring for Exposure to Hazardous Chemicals - Guide for workers
- Australian standards:
- AS/NZS 1715;2009 Selection, Use and Maintenance of Respiratory Protection
- AS/NZS 2234.8:2014 Safety in Laboratories Part 8 Fume Cupboards
In the event of suspected exposure, call the Poisons Information Centre on 131 126.