Fumigation is the most effective way of pest control in transport chain by introducing toxic gas to kill the pests. There are many fumigant chemicals in use including Methyl Bromide which is also an ozone depleting substance. The most common chemicals used are 1,3-dichloropropene, dazomet, chloropicrin, formaldehyde, hydrogen cyanide, iodoform, methyl isocyanate, phosphine, sulfuryl fluoride.
Grubs and larvae of insects and other species can infest cargo, as well as packaging, dunnage, etc., associated with the cargo, at any stage during harvesting, manufacture, processing, storage, packing or transport. These can spoil foodstuffs, textiles, leather goods, furniture, art and antiques, affect electronic equipment, contaminate sterile goods or deface consumer packaging or labelling, making the goods unfit for sale and therefore valueless. 
In this article, we will look at methods of fumigating containerized cargo and the provisions of carriage of fumigated containers on board ships.
Most commonly used fumigants are Phosphine and Methyl Bromide
This process requires a long period of time to work completely. This can be applied with little technical training as it is supplied in sachets, tablets or pressed plates containing Magnesium Phosphide or Aluminium Phosphide. These generate Phosphine gas when exposed to the moisture in the air. The gas has a slight “fishy garlic” smell and breaks down into a powdery grey residue.
The rate of generation of Phosphine depends on the temperature, the airborne moisture and the extent to which the generating material is exposed to the air.
Symptoms of poisoning by inhalation of Phosphine include nausea, vomiting, headache, feeling weak, fainting, pain in chest, cough, chest tightness and difficulty breathing. Pulmonary oedema (the presence of excess fluid in the lungs usually due to heart failure) can follow, usually within 24 h, but sometimes this is delayed for some days. 
Methyl Bromide Fumigation
Fumigation with Methyl bromide is a relatively rapid process that can normally be completed in less than 48 h. Symptoms of poisoning by inhalation of Methyl bromide include headaches, dizziness, and eye irritation, coughing, nausea, abdominal discomfort, and numbness of feet. Higher exposure will bring about unconsciousness to central nervous system, convulsions, and loss of vision, balance and hearing. Methyl bromide is supplied as a gas. So, during application, expertise is required to carry out the operation. 
Section 5.5.2 of IMDG Code stipulates the requirement of fumigated containers on board sips. A fumigated cargo transport unit shall be marked with a warning mark affixed at each access point in a location where it will be easily seen by persons opening or entering the cargo transport unit.
The marking shall be a rectangle. The minimum dimensions shall be 400 mm wide x 300 mm high and the minimum width of the outer line shall be 2 mm. The marking shall be in black print on a white background with lettering not less than 25 mm high.
This mark shall remain on the cargo transport unit until the fumigated cargo transport unit has been ventilated to remove harmful concentrations of fumigant gas and the fumigated goods or materials have been unloaded.
Class 9 placard must not be affixed on fumigated containers unless there is a class 9 cargo loaded in the container.
Fumigation in transit
If the fumigated containers are loaded on board ships without ventilating, then below information must be provided by the shipper to carrier.
- UN 3359, fumigated cargo transport unit, 9, or UN 3359, fumigated cargo transport unit, class 9;
- The date and time of fumigation;
- The type and amount of the fumigant used; and
- Instructions for disposal of any residual fumigant including fumigation devices (if used).
Even though stowage category is B, on or underdeck, preferred stowage of fumigated (non-ventilated) containers are on deck and must only be stowed clear of living quarters and at least 6 meters from vent intakes.
For any reason if the fumigated, non-ventilated, container is stowed under deck it must only be in holds which has mechanical ventilation with rate of ventilation at least two air changes per hour on empty cargo space. The ship should carry gas-detection equipment for the fumigant gas involved.
There are no regulatory reqrueiments for loading containers ventilated prior loading on board ships other than marking the date of ventilation on the fumigant mark affixed on the container.
Country wise differences
There may be different rules in different countries for accepting fumigated containers. United Kingdom does not permit fumigation with Methyl Bromide and they use Aluminium phosphide and India does not permit Aluminium phosphide.
If a U.K. fumigated container carrying grains or pulses the commodity must be re-fumigated with methyl bromide upon its arrival in India by the NPPO accredited agencies and under supervision of PQ officer.
For more information visit
 MSC.1/Circ.1361 Revised Recommendations on The Safe Use of Pesticides in Ships Applicable to The Fumigation of Cargo Transport Units