There are many chemical health hazards on board ships, some are specific to tankers and other ships with dangerous cargoes, but many relate to chemicals used on a far wider range of ships. Exposures may be higher than on shore and exposure periods more prolonged as crewmembers live and work on board. The management of health hazards is often less developed on board than on shore and safe working practices are less accessible for supervision and inspection. Chemical exposures on board ships have the potential to cause a wide range of harmful effects, some immediate from exposure to acutely toxic substance, others such as the cancer risks from asbestos and certain hydrocarbons and their combustion products long delayed and often not detectable until after retirement. Many routine tasks on board, especially cleaning, painting and maintenance can give risk from exposure to solvents and detergents.
Routes of entry
Any substance is only capable of causing harm if it makes contact with or enters a person’s body. Hence it is important to be able to assess the likelihood of this happening. Both the physical (volatility, particle size) and chemical properties of any specific substance will determine the extent of uptake by the body, while the nature of its interactions with the biological processes in the body will determine not only the nature of any harmful effects but also the speed with which the substance is metabolised and excreted or whether it is stored in tissues.
Inhalation is the most important route of exposure. The surface area of the lungs is very large and designed for the process of gas exchange. Any hazardous gases or vapours from volatile substances inhaled into the lungs can have a direct effect on the the lungs causing irritation, allergy or cancer. They can also be absorbed into the blood stream and transported around the body to have an effect on organs such as the liver, kidneys and blood.
Dust and fibres can also be inhaled. The upper parts of the respiratory systems have some mechanisms to trap and remove dust and fibre. However very fine particles and fibres can be inhaled into the deep lung where the body is not able to remove them. Dusts and fibres can have effects on the lungs similar to gasses and vapours but also including fibrosis. Soluble dusts and fibres can also be dissolved and absorbed into the body.
Skin Contact/ Absorption
Some hazardous substances can cause irritant or allergic reactions when they come into contact with the skin. Substances that are soluble in fat can pass through the skin and be absorbed into the blood stream, circulate in the body and have an effect on organs within the body. If the skin is cut, or abraded absorption can occur even quicker. The eye is particularly susceptible to irritant and corrosive effects from chemicals, including gasses and vapours.
Most people don’t swallow harmful substances on purpose, however it is possible to accidentally ingest a toxin while eating, drinking or smoking after work with chemicals. This occurs when chemical substances on hands and clothing contaminate food, drink and cigarettes. Ingestion can also occur where dusts and fibres trapped in the upper parts of the respiratory system are coughed up and swallowed. It may also occur when chemicals stored in unlabelled containers, particularly those normally used for food or drink, are mistaken for a .
Substances may be injected or pushed through the skin, such as in the case of needle stick injury or from high-pressure applications such as pressure washing, grit blasting, fuel injectors or hydraulic systems. Severe local tissue damage can result from high-pressure injection.
Determining the likely routes of entry and having information available on any adverse effects that can be anticipated from uptake of a substance forms the basis for deciding on the appropriate precautions, including safe work practices. It also shows whether active monitoring or surveillance for harmful effects will help confirm the adequacy of preventative actions.