Methyl bromide technical fact sheet

Methyl bromide is a colourless, non-flammable gas with no taste or odour at low concentrations. Therefore, it often has a small amount of chloropicrin (a tear gas agent with strong, sharp odour) added to warn of its presence. However, at levels well above the workplace exposure standard (5 ppm or 19 mg/m3), methyl bromide itself may present a sweetish odour. Adequate controls for the proper use, handling and storage of methyl bromide 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. Methyl bromide (bromomethane) ranked eight based on these criteria.

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Sources of exposure

Methyl bromide is used as a fumigant to prevent unwanted pests, for example insects, rodents, weeds and disease-causing organisms, in a wide range of agricultural and horticultural crops and in wood products.

Methyl bromide is easily absorbed through inhalation and skin contact. It is fat soluble and able to penetrate the blood brain barrier and damage the central nervous system. Ingestion is unlikely but methyl bromide is extremely poisonous if ingested.

Methyl bromide gas is heavier than air and may collect in low spots or poorly ventilated places. It can pool in the back of a container, diffuse into tightly packed or sealed cartons, or even become trapped in gloves, boots or other clothing.

Health effects

Methyl bromide has local and adverse body effects. It is rapidly distributed to the lungs, adrenal glands, kidneys, liver, nasal turbinates, brain, testes and adipose tissue.

Acute exposure can be fatal. Injuries include:

  • severe chemical burns of the skin, eyes and airways
  • severe kidney damage
  • central nervous system damage
  • delayed chemical pneumonia which produces water in the lungs (pulmonary oedema).

Onset of symptoms may be delayed from 30 minutes, up to two days post-exposure has been observed.

Prolonged or repeated chronic exposure may produce neurological effects such as mental confusion, lethargy, blurred vision, loss of co-ordination and muscle weakness. Low level chronic exposure has caused a general degeneration of peripheral nerves that spreads towards the centre of the body.

Methyl bromide gas easily penetrates most protective clothing (eg cloth, rubber and leather). Repeated skin exposure may cause contact dermatitis.

Labelling and safety data sheets

Manufacturers and importers of methyl bromide 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. Methyl bromide has a workplace exposure standard of 5 ppm or 19 mg/m3averaged 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).

Health monitoring

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. Methyl bromide 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.

Control measures

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 methyl bromide if reasonably practicable.
  • Use the lowest amount necessary.
  • Ensure adequate engineering controls including adequate ventilation.
  • When used as a fumigant, employers must ensure that fumigation is carried out by a licensed fumigator.
  • 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.
  • Decanting should be avoided. If methyl bromide is decanted to a new container, it must be properly labelled.
  • When unpacking shipping containers, the containers must be vented of methyl bromide before workers enter them. Any methyl bromide vented from the container should preferably be captured using recapture technology.
  • 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

More information is contained in:

  • Australian standards:
    • AS/NZS 1715;2009 Selection, Use and Maintenance of Respiratory Protection
    • AS 2476-2008 General fumigation procedures

In the event of suspected exposure, call the Poisons Information Centre on 131 126.

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