1. What are dangerous substances?
‘Dangerous substances’ are generally chemicals or metals which, because of their physical properties, are immediately dangerous and can lead to serious injury or death from a variety of causes. Some may cause injury on contact alone, whereas others cause harm through chemical reaction with other substances.
2. What types are there?
Dangerous substances can be grouped into four main categories:
- directly injurious substances which can cause harm with or without prior chemical reaction;
- water-sensitive materials which react with water or steam to create heat or flammable/explosive gases;
- oxidising agents which produce oxygen, either naturally or when exposed to heat, increasing the risk of fire or explosion; and
- toxic substances which poison the system by inhalation, ingestion or absorption into the skin.
Some substances can be classified under more than one of these headings and therefore pose even greater risks.
3. Where might they be encountered?
Dangerous substances are most commonly encountered by freight staff working at ports, inland clearance depots, airports and some oil installations.
4. What about fumigants?
Fumigants are the dangerous substances you are most likely to meet. They are used to rid containers of rodents and insect pests. Fumigants are often used before the containers are shipped to the EU. If the containers are not properly ventilated on arrival, the fumes can pose serious hazards to officers working in them. There are three common types of fumigant, each posing its own particular hazards:
Methyl bromide (bromomethane): A highly toxic chemical which is widely used as a fumigant, particularly with containers of soil or timber. Although methyl bromide is highly toxic, the symptoms of poisoning can take several hours to develop. They include:
- burns to the skin from prolonged contact with the liquid form of the chemical;
- massive accumulation of fluid in the lungs from inhalation of vapour;
- damage to the brain and nervous system and, possibly, the kidneys.
Even short-term exposure to methyl bromide fumes can cause discomfort, including headaches, sore eyes, stomach pains and numbness of the feet. These effects can last several days, but their severity depends on the concentration and on the length of exposure. Long-term exposure to methyl bromide can even result in death.
Aluminium phosphide (phosphine): Pellets of aluminium phosphide are used to fumigate containers of foodstuffs, tobacco and other perishable goods while they are in transit. The pellets deteriorate during the journey, releasing phosphine gas which destroys pests and then disperses within two or three weeks. Danger arises when:
- two or three weeks have not elapsed since fumigation; or
- the pellets were placed in a secluded area where they could not decompose efficiently; or
- the fumigation records are missing or unavailable.
Incorrectly fumigated containers are occasionally imported from Africa, South America and the Middle and Far East. Phosphine gas is colourless, but has an unpleasant odour reminiscent of decayed fish. If inhaled, it can inflame the respiratory passages and affect the central nervous system. Symptoms include tremors, nausea, vomiting, headaches and gastric pain. Serious cases can even lead to coma or death.
Hydrogen cyanide: This fumigant is less widely used than methyl bromide and aluminium phosphide, but is particularly dangerous. It has a smell reminiscent of almonds. Even at low concentrations it can cause dizziness, nausea, headaches and stomach pains, leading to unconsciousness and paralysis. Inhalation of high concentrations can rapidly lead to death.
5. What about chemicals?
In addition to fumigants, other chemicals may be present in dangerous quantities in containers that have been sealed for even a short period. These may be caused by leakage of cargo (manifested or un-manifested) or by a chemical reaction between goods.
The Annex to Commission Directive 2006/15/EC of 7 February 2006 gives details of the indicative occupational exposure limit values for a list of common chemicals together with their EINECS (European Inventory of Existing Commercial Chemical Substances) and CAS (Chemical Abstracts Service) numbers to assist in identification.
If any of these are detected or the MSDS indicates, or you suspect, that any of these are present, you should seek further advice and should not enter the container until you receive confirmation that it is safe to do so. Remember that, in addition to vapours, some chemicals may also be readily absorbed through the skin.
Regulation 24/1998 applies. The Commission also regularly publishes updated lists of threshold values by means of additional Directives. The current directive in force is Directive 2007/30/EC.
Threshold limit values are revised as a result of further research and experience, you should check both Commission directives and your national legislation for current exposure limit values.
6. What can be done to reduce the risks?
Fumigation operations are very strictly controlled. Certain types of fumigants are prohibited and protective measures must be taken to minimise the risks of ill health. You must keep well away from containers when fumigation operations are being carried out. Most importers will leave containers open for an hour or so once they arrive to allow fumes to escape. You should not attempt to open or enter any container until the importer (or his agent) tells you it is safe to do so. Managers of staff involved in covert operations must assess the risks and take whatever safety precautions are required. All work must be done in a safe manner at all times.
7. What should I do if I feel ill?
If you start to suffer any discomfort while working in a container or examining any substances, stop work immediately and leave the area. You should also seek medical attention — even if you feel that you have recovered — and report the incident.
8. What about other dangerous substances?
Some types of dangerous substances require special storage arrangements. For example, water-sensitive materials must be kept in waterproof containers and are sometimes stored in oils if particularly sensitive (e.g. sodium). They must be kept away from rooms with automatic sprinkler systems.
Oxidising agents should be kept away from liquids with a low flashpoint, such as oils. Oxidising agents and liquids with a low flashpoint must both be kept away from sources of heat. Because oxidising agents supply their own oxygen, conventional fire-fighting equipment which relies on smothering could be ineffective.
If you have to work near any dangerous substances, you should wear appropriate safety clothing. You must never touch, inhale or taste anything which you suspect is dangerous.
Remember: the most effective way of lessening risks is by avoiding dangerous substances altogether.
