Engine room personnel have an increase incidence of lung cancer, partly due to exposure to asbestos, which also causes pleural cancer (mesothelioma). Engine room personnel may also be exposed to carcinogenic polycyclic aromatic hydrocarbons (PAH) or nitroarenes from bunker or lubricating oils, engine exhaust, and soot. The dermal uptake of PAH from oil on the skin seems to be more important than exposure by inhalation, and increased levels of biomarkers of exposure and genotoxic effects have been described. Carcinogenic PAH have been detected in heavy fuel oils, lower levels are found in marine diesel oil and in used lubricating oils.
A wide range of other chemicals such as additives for the ship’s fuel and water treatment systems, solvents, corrosives and detergents are used and engine room staff also undertake the more complex maintenance tasks elsewhere on board where they may encounter a range of chemical risks.
It is important effective engineered precautions such as ventilation systems are in place and operating correctly and that the engine room crew have knowledge about and are aware of the health hazards of the materials they come into contact with, and use good work practice, for instance respiratory protection and appropriate gloves to prevent exposure (see personal protection below).
Paint may contain several hazardous substances, such as solvents (usually hydrocarbons, some of which are neurotoxic) and metals (lead oxide), as well as irritating chemicals, such as biocides, isocyanates, which may cause asthma, and epoxy resins, which may cause allergic dermatitis. The manufacturer’s instructions for safe handling must always be followed and painted areas defined and made off limits to other crewmembers it hazardous components may be released.
Cleaning agents are used in all parts of a ship, including food preparation areas and cabins. These are usually either solvent or alkaline water based products. The solvent base usually contains hydrocarbons, some of which are neurotoxic. Chlorinated hydrocarbons, such as trichlorethylene, may be used and these are hepatotoxic and may sometimes be carcinogenic . Strongly alkaline cleaning agents can cause serious eye injuries from splashes, and protective glasses should be used when handling these substances. They may also cause irritation of the skin and respiratory mucosa. Information and knowledge of health hazards are important. Toxic substances should be replaced by less toxic substances when possible and appropriate personal protection should be used.
The IMO publish recommendations to be used when entering enclosed spaces. An enclosed space is defined as a space which has any of the following characteristics:
- limited openings for entry and exit;
- inadequate ventilation; and
- is not designed for continuous worker occupancy,
and includes, but is not limited to, cargo spaces, double bottoms, fuel tanks, ballast tanks, cargo pump-rooms, cargo compressor rooms, cofferdams, chain lockers, void spaces, duct keels, inter-barrier spaces, boilers, engine crankcases, engine scavenge air receivers, sewage tanks, and adjacent connected spaces. This list should be produced on a ship-by-ship basis to identify enclosed spaces particular for each vessel.
A preliminary survey of MAIIF (Marine Accident Investigators' International Forum) members revealed that there have been at least 101 enclosed space incidents resulting in 93 deaths and 96 injuries, since the first IMO recommendations on enclosed spaces were adopted in November 1997. The unrecorded number is believed to be much higher. The MAIIF statistics have identified the following as being the most commonly contributing factors in enclosed space accidents;
- lack of knowledge
- Personal Protective Equipment (PPE) or rescue equipment not being used, not available, of inappropriate type, improperly used, or in disrepair;
- potentially dangerous places not being identified;
- inadequate or non-existent signage;
- inadequacies in Safety Management Systems; and
- poor management commitment and oversight.
Safe entry into confined spaces
The present safety recommendations regarding enclosed spaces are generally heavily reliant on organizational arrangements and thus susceptible to human error. Technical preventive measures are largely non-existent, even on modern ships. An important undertaking is therefore to seek technical methods to prevent accidental entry into enclosed spaces. Natural ventilation of stairways can be slow and several hours may be required to reach safe levels. Mechanical ventilation may be the only effective practical solution if the stairway needs to be accessed within a reasonable time. Fresh air should be injected at the bottom of the stairway, thus displacing contaminated air to the outside. Suction ventilation should be avoided since contaminated air may enter from a cargo hold. Appropriate measuring instruments need to be available to confirm freedom from the risks anticipated. These will be determined by the nature of the enclosed space and any areas that may connect with it and the presence of hazards from cargo, fumigants or inerting gasses. These same considerations will determine the need for respiratory and other protective equipment (see personal protection, below).
A simple and effective preventive measure is to lock access doors leading to enclosed spaces during the voyage and ensure that the key is kept by a responsible person until safe entry can be arranged. Although not specified in the IMO Recommendations, access doors may well be labeled on the outside and the inside with warning signs about low oxygen content, toxic atmosphere, or the skull and crossbones symbol, visible both when the door is open and closed. A door opened for the purpose of ventilating the stairway may be regarded as an invitation to enter by an uninformed person. A chain or rope with a warning sign positioned across the door opening could prevent such accidental entry. The storage of tools or supplies inside enclosed spaces should be avoided since fatal accidents have occurred when people have entered to collect these items.
Measurement of toxic concentrations
It is essential to measure the concentration of the toxic gases and the level of oxygen depletion prior to entry into an enclosed space. Oxygen measurement alone will not be sufficient if another toxic substance is present. Relevant national occupational exposure limits should be used as reference values. Unless fixed sample lines leading to the outside are installed it may be difficult to measure deep inside an enclosed space. Since unventilated pockets of air may exist, personal monitors should be worn when entering an enclosed space and a trained assistant maintaining communication with the person inside should be placed outside. Factors that may aggravate the toxic effects are combined effects for example from low oxygen level and simultaneous CO presence. Heavy physical work-load will increase the uptake of toxic chemicals and different personal susceptibility is common.
Calibration to confirm the reliability and validity of the monitoring equipment is important. Underestimation of concentrations is dangerous, while false alarms may cause unnecessary agitation and costly delays. Instrument manufacturers can provide information about calibration procedures, possible cross-sensitivities or limits in extreme environments e.g. low oxygen, high CO2, high humidity or below freezing temperatures.