A rational approach to precautionary measures is essential. The main principles are those outlined in chapter 14 on health, environment and safety risk management. There are certain aspects of risk management that are specific to substances that are potentially hazardous to health.
Material Safety Data Sheets (MSDS)
Material Safety Data Sheets (MSDS) provide information that must be supplied by the chemical manufacturer or importer for all hazardous materials. Those responsible for purchasing materials for use on board ships should ensure that MSDS are received for all materials purchased and that these are then made available in an accessible way on board the ships that are supplied with the materials. The MSDS is a summary of the important health, safety and toxicology information on the ingredients of the chemical or mixture.
A current MSDS, normally not more than two years old, should be available for every hazardous chemical agent in use on-board. Hazardous substances must also be labelled with appropriate warning and identification labels. The information on the sheet should form the basis for precautions taken and if there are any uncertainties, or if adverse effects occur, despite following the recommended precautions then expert advice should be obtained or the supplier contacted for clarification. At least one maritime administration, Denmark, has developed a centralised database for the MSDS normally used on board.
Respiratory Protective Equipment (RPE)
Respiratory protective Equipment (RPE) is required when engineering and administrative controls are not sufficient to protect a worker from a hazardous atmosphere, and a worker is or may be exposed to an airborne contaminant (or mixture) in a concentration exceeding the occupational exposure limits (OEL) or the atmosphere has or may have an oxygen concentration of less than 19.5% by volume.
Selection of RPE.The type used should be based on:
- The nature of the contaminant
- The concentration or likely concentration of any airborne contaminant
- Duration of exposure
- The concentration of oxygen
- The warning properties of the contaminants (odour, taste, irritation)
- The need for emergency escape
- Routes of exposure and health effects relevant to the contaminant.
- The Assigned Protection Factor (APF) of the RPE
It may be necessary to undertake monitoring of the levels or contaminants and of oxygen prior to the decision on the type of RPE to use. The reasons for using the type selected should be documented.
The UK Health & Safety Executive publication Selection of Respiratory Protective Equipment provides guidance on selection of the correct level of RPE. RPE must be properly fitted, used and maintained to remain effective. Systems need to be in place on board to ensure that fit is tested and that the equipment in cleaned and serviced.
There are two main types of RPE:
1. Air-Purifying Respirators remove the contaminant from the breathing air by filtration or chemical absorption. They can only be safely used only when all of the following criteria are met:
- Contaminants are present in concentrations less than below those that are immediately dangerous to life or health (IDLH).
- Oxygen concentration must be between 19.5 – 23.5%.
- In non-emergency situations, where concentrations are known.
Air Purifying Respirators cannot not be safely used for Hydrogen Sulphide (H2S) at concentrations greater than 10ppm.
Disposable filter masks are designed for nuisance dusts and particulates, aerosols, fumes at low concentrations. They are not suitable for protection against gasses or vapours or for toxic dusts.
Re-useable RPE should be stowed in a clean bag or container. Disposable masks should be changed at the end of every shift or if they become heavily contaminated. Particulate and gas filters should be changed out intervals determined by the risk assessment for each specific task.
2. Breathing apparatus/air-supplied respirators provide clean air from an uncontaminated outside source or from a tank of compressed air. They must be used in situations where there is a potential for:
- Exposures that are immediately dangerous to life or health (IDLH).
- Oxygen-deficient atmospheres (Below 19.5 %.)
- Chemical concentrations greater than those for which air purifying respirators are designed.
- Where concentrations of contaminants are unknown.
Detailed procedures for safe working practices such as back up crew and equipment and time limitations on use to prevent exhaustion of air tanks. This is especially so if the equipment is used in confined spaces. The quality of air used both for air supplied and self-contained equipment and the compressors used for refilling tanks must conform to recognised quality standards.
Protective Clothing (including gloves)
Where there is risk of skin contact the primary focus should be to prevent exposure or control it by engineering measures or work practices. However, where it cannot be guaranteed that skin contact with chemicals will not occur chemical-protective clothing may be required.
A substance can pass through protective clothing to reach the skin in three ways:
- Penetration through tears, pinholes, openings and seams.
- Degradation of the material.
- Permeation through the body of the intact material.
The material used to make the protective clothing will determine both its strength and the likelihood of permeation. The material chosen will depend on the properties of the chemicals being used (MSDS may give recommendations) as well as on other aspects of the task, such as the liability for tears or abrasions to equipment to occur. Common chemical-protective clothing materials include:
- Fluorinated and nitrile rubbers.
- Flexible laminates.
- Polyvinyl alcohol (PVA).
- Polyvinyl chloride (PVC).
Eye and face protection includes safety glasses, chemical goggles and face shields. The equipment used must be suitable for the task being undertaken. This may include safety aspects such as the possibility of eye injury from high velocity fragments or from ultra violet light from welding.
Many chemicals can cause significant harm to the eyes and skin if they come into contact. Health effects may include corrosive burns, irritation or allergic reactions. As a single brief exposure may be sufficient to cause permanent damage, especially to the eyes, it is important that protective devices are worn at all times when the hazard is present.