For the study, Hinz and her colleagues were assisted by the New Zealand Customs Service. Staff used probes pushed through rubber seals on container doors to collect gas samples from 490 sealed containers. Hinz also directly collected air samples from dozens of different vessels to track how the concentration of compounds changed in real time as the vessel was opened and the inside air mixed with fresh outside air.
Investigation revealed a large number of unpleasant substances. Customs officials found methyl bromide, a compound that overwhelms Rotterdam dock workers in 3.5% of sealed containers. They found formaldehyde in 81% of the containers and ethylene oxide in 4.7% to mention a few chemicals. Exposure to ethylene oxide can cause a variety of unpleasant symptoms, including nausea, vomiting, and diarrhea. The preservative, formaldehyde, is carcinogenic and may cause internal irritation if inhaled, among other symptoms.
In their study, Hinz and her colleagues found that some of the measured concentrations were high enough to cause an acute reaction that caused immediate symptoms. But, Hinz says, it’s actually unusual for workers to come into direct contact with such high levels of toxic gases. Instead, repeated exposure to low concentrations poses a more common but still notable risk. For example, chronic contact with these chemicals can potentially increase your risk of cancer or cause psychiatric problems. However, relatively few studies have been conducted on the hazards of chemicals inside cargo containers.
“Obviously, I think we need to be careful,” Hinz said. It requires a lot more attention than you might think.
Gunnar Johanson, a toxicologist at the Karolinska Institute in Sweden, who served as a peer reviewer of Hinz’s work, agrees with her assessment.
“I don’t know exactly how big the risk is, but it’s an unnecessary risk because it can be easily addressed,” he says. Better ventilation is required.
A few years ago, Johansson and his colleagues were called in to investigate a suspected container in Sweden. It was full of rice, but there was also a strange blue bag full of white powder inside the container. When Johansson analyzed the air, he discovered phosphine, a fumigant. by concentration fatally high.
To protect dock workers, Johanson and his colleagues designed a device that attaches to a brew pan and attaches to a small but tiny ventilation hole on the side of most containers. Experiments have shown that when the device is turned on, the concentration of harmful gases drops within minutes.
“We can reduce volatile pollutants by about 90 percent in less than an hour,” says Johanson. He added that the device is now in use by the Swedish Customs Service.
Martin Cobbald, Managing Director of Dealey Environmental, a UK environmental services company, says the transport and logistics industry needs to raise awareness of the risks associated with exposure to hazardous gases in shipping containers.
His company often has contracts to open and ventilate containers, but “we rarely do that for the range of people we have to do,” he adds.
Hazardous chemicals hiding inside shipping containers
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