In their study, Hintz and her colleagues sought help from New Zealand customs authorities. Workers collected gas samples from 490 sealed containers using a probe through the rubber seal of the container door. Hinz himself collected air samples from dozens of other containers, tracking how the concentration of the compound changed in real time as the container was opened and the air inside was allowed to mix with fresh outside air.
The investigation found a lot of harmful substances. Customs authorities found methyl bromide in 3.5 percent of hermetically sealed containers, a compound that overwhelmed Rotterdam dockworkers. They found formaldehyde in 81% of the containers and ethylene oxide in 4.7%, to name a few. Exposure to ethylene oxide can cause a variety of unpleasant symptoms, including nausea, vomiting, and diarrhea. Formaldehyde is a preservative, carcinogenic, and can cause symptoms such as internal irritation when inhaled.
In their study, Hinz and her colleagues found that some of the measured concentrations appeared to be high enough to cause an acute response that triggered immediate symptoms. In practice, however, it is unusual for workers to be directly exposed to such high concentrations of toxic gases, Hinz said. Conversely, there are more common but still noteworthy risks associated with repeated exposure to low concentrations. For example, long-term exposure to these chemicals may increase the risk of cancer or cause mental problems. However, relatively little research has been done on the risks of chemicals in containers.
“I definitely think it needs more attention than it gets,” Hinz said.
Gunnar Johanson, a toxicologist at the Karolinska Institutet in Sweden who was a peer reviewer of the Hinz study, agreed with her assessment.
“We don’t know exactly how big the risk is, but it’s an unnecessary risk because you can easily address it,” he said. All that is needed is better ventilation.
A few years ago, Johansen and his colleagues were asked to inspect a suspicious container in Sweden. It contained rice, but inside the container there was also a strange blue bag with white powder inside. When Johansen analyzed the air, he found that phosphine, a fumigant, was present in lethal concentrations.
To protect dockworkers, Johanson and his colleagues designed a device that connects to an extraction fan and to the existing but small vents on the sides of most containers. Experiments have shown that once the device is turned on, the concentration of harmful gases drops within minutes.
“We can reduce volatile pollutants by about 90 percent in an hour,” says Johanson. He added that the device is currently used by Swedish customs authorities.
Martin Cobbald, managing director of UK-based environmental services firm Dealey Environmental, said the shipping and logistics industry should raise awareness of the dangers associated with exposure to harmful gases in containers.
His company often contracts to open and vent containers, but, he added, “we’re doing things that are hardly within the scope of what we’re supposed to be doing.”