Occurrence of Fumigants and Hazardous Off-gassing Chemicals in Shipping Containers Arriving in Sweden

Containerized cargo shipment makes up the backbone of international trade. The principal aim of this cross-sectional study was to establish a qualitative and quantitative description of gaseous fumigants and volatile off-gassing substances facing workers tasked with entering shipping containers. A total of 372 packed and 119 empty shipping containers were sampled in six ports and two distribution centers in Sweden. Fourier-transform infrared spectrometry (FTIR) and photoionization detection (PID) were the analytical methods applied to the bulk of samples. A small number of adsorbent samples were analyzed using gas chromatography-mass spectrometry (GC-MS). The results were compared to Swedish occupational exposure limits (OELs), the closest parallel to relevant work situations. Based on the FTIR analyses, 30 of 249 (12%) containers arrived with concentrations of fumigants and off-gassing substances above the 8-h OELs and close to 7% were above the short-term exposure limits. Eight detected chemicals were classified as carcinogens and 4% of the containers arrived with levels of carcinogens above the OELs, at a maximum 30 times the 8-h OEL. Considerable differences were observed between ports, ranging from 0 to 33% of containers arriving with concentrations above the OELs. It is believed that all observation results, apart from a single instance of a confirmed fumigant, phosphine, at 3 p.p.m., and possibly three instances of carbon dioxide, can be attributed to off-gassing substances. The FTIR methodology proved useful for quick preliminary checks and in-depth screening and identification. The PID method produced both false-negative and false-positive results where only 48% matched the FTIR observations. Adsorbent sampling with GC-MS analysis was useful for confirming volatile organic compounds but was deemed too slow for day-to-day screening. The high frequency of contaminated containers, the detection of several carcinogens, and the sporadic occurrences of high levels of fumigants are serious concerns that need to be properly recognized in order to protect the workers at risk.