ROTTERDAM - Governments are well aware of the danger, but consumers have no idea. One out of five freight containers arriving in European ports has been fumigated with extremely dangerous, carcinogenic or neurotoxic gases.

It is a vast phenomenon: one million containers filled with imported goods arrive in Europe by ship every week. These toxic substances are odorless, colorless and can affect everyone from port workers, customs officials, logisticians, drivers, warehousemen, store employees and even consumers.

In 2010 in the Netherlands, two workers unpacking a container from China filled with glass packed in timber pallets were severely contaminated. One of them spent five days in a coma while the other experienced serious health problems: major weight loss, loss of smell and taste.

These toxic gases are left over from the fumigation process, a necessary – sometimes mandatory – operation to kill micro-organisms and pests before transport, in order to prevent the introduction of parasites, bacteria and diseases into the importing country.

The fumigation process is usually subject to many precautions. Shipping containers must be sprayed with gas and then ventilated before goods can be loaded. They must display specific labels on the door specifying the date of fumigation and the fumigation gas used.

In March 2010, the EU banned the use of methyl bromide, a dangerous pesticide -- but many countries, including the U.S., still use it. What’s worse, very few countries actually indicate the presence of toxic gas on their containers, to avoid having to de-gas them.

Another more insidious source of toxicity, which puts port workers and consumers at risk, is the vapors emanating from the merchandise itself during transport. Furniture, shoes, clothes made in Asia – mostly Vietnam and China -- frequently contain toluene and benzene solvents, which are carcinogen. When this is the case, there are no labels on the shipping container warning port workers to equip themselves against toxic fumes. The only solution is to test the air inside the containers, an operation that is seldom carried out.

From medicine to mattresses

Can fumigation gases contaminate goods inside the containers? A 2005 study from the Netherlands National Institute for Public Health and Environment revealed that imported medicine, food and mattresses contained methyl bromide.

Three years later, during the 18th Annual Congress of the European Respiratory Society, researchers from the Institute for Occupational and Maritime Medicine at Hamburg University revealed the huge risks associated with fumigated containers. Out of 200 containers arriving in Hamburg, Germany, and 300 arriving in Rotterdam, Netherlands, Xavier Baur and Lygia Budnik concluded that 97% of freight containers contained residues of pesticide fumigants and toxic industrial chemicals, mostly 1.2-dichloroethane and methyl bromide, as well as benzene and toluene. About 19% of them had levels exceeding the permitted exposure level. The German researchers told the congress that the fumigants and toxic products “contaminated the transported goods, penetrating into them and settling there.”

Belgium and the Netherlands have already implemented drastic measures. Every time there is a doubt, the containers are tested for toxic gas. Dutch customs require a certificate confirming the absence of toxic fumes time-stamped less than two hours before its staff is called in. Jan De Jong, leader of the Dutch trade union FNV Bondgenoten, has called on governments to go even further by banning certain toxic chemicals worldwide.

Trade unions have asked for de-gassing stations to be installed in ports and for inspections to be increased. What about companies? A 2006 study by the Dutch Environment Ministry showed that 97% of companies had never analyzed the risks linked to fumigation. Since then, some companies like IKEA have started systematically measuring the toxicity of their containers and their furniture.