SIFT-MS is the first technology proven capable of rapidly, simply and accurately detecting and quantifying a broad range of fumigants and TICs, without unnecessarily disrupting movements through freight-handling facilities. With an ability to identify compounds well below risk levels for long-term exposure, SIFT-MS is successfully protecting workers in the shipping and border security industries.

Introduction to Toxic Industrial Chemicals and Fumigants


One consequence of growing international trade and industrialization is the increasing trade and shipment of toxic industrial chemicals (TICs). With standards for and attitudes to these chemicals varying greatly between jurisdictions, frontline workers in the shipping and border security industries face exposure to very real, often undocumented, dangers.

Unfortunately, given the size and diversity of international trade, it has not proved possible to accurately track which fumigants and TICs are being used and shipped, what concentrations are being used and shipped, or what qualifications and experience those doing the fumigation or packaging have. A recently published study1 involving analysis of over 2000 containers arriving in the Port of Hamburg over a 10-week period clearly illustrates this problem.

Chronic reference exposure levels were exceeded in 70% of containers. Still more alarming was that 36% of the containers had concentrations over acute reference exposure levels. This means safeguards are needed to protect the health of workers involved with loading, transport, inspection, and unloading of imported goods, particularly shipping containers.

In this article, we overview the common fumigants and volatile toxic industrial chemicals TICs and compare commercially available detection technologies, including Selected Ion Flow Tube Mass Spectrometry (SIFT-MS).

Common Fumigants


A variety of fumigants are commonly used against biosecurity threats, some of which are listed in Table 1. The chemical and toxicities properties of these fumigants are very diverse.

Table 1 also lists time-weighted average (TWA) exposures given by the Australian Government’s. Note that acceptable exposure levels may differ from country to country. For example, in the United States exposure limits may be found in the National Institute for Occupational Safety and Health Pocket Guide to Chemical Hazards.

When protecting workers from these toxic chemicals it is recommended that several fumigants be detected at much lower levels than those indicated (for example, ethylene dibromide and methyl bromide, which are known carcinogens, and ethylene oxide and formaldehyde, which are suspected carcinogens).

Table 1. Common fumigants, their uses and occupational exposure limits.
Fumigant name (synonyms) [CAS number1]Examples of fumigant useTWA2
Chloropicrin (trichloronitromethane) [76-06-2]Soil; timber and timber products0.1 ppm [0.67 mg/m3]
Ethylene dibromide (1,2-dibromoethane) [106-93-4]Soil; post-harvest for crops; citrus and tropical fruits; vegetables; beehives0.5 ppm [3.9 mg/m3]
Ethylene oxide (oxirane, 1-2-epoxyethane) [75-21-8]Grains; dried fruits and nuts1 ppm [1.8 mg/m3]
Formaldehyde (methanal) [50-00-0]Eggs (killing viruses and bacterial); most commonly present due to outgassing from manufactured goods1 ppm [1.2 mg/m3]
Hydrogen cyanide [74-90-8]Fresh produce; structures; aircraft10 ppm [11 mg/m3]
Methyl bromide (bromomethane) [74-83-9]Very widely used general fumigant, but especially for wood35 ppm [19 mg/m3]
Phosphine [7803-51-2]Grains; tobacco; dried fish and meats; fresh fruits; beverages0.3 ppm [0.42 mg/m3]
Sulfuryl fluoride (VikaneTM) [2699-79-8]Structures; timber and timber products; shipping containers5 ppm [21 mg/m3]
  1. ‘CAS number’ refers to the unique identifier assigned to a chemical compound by the American Chemical Society’s Chemical Abstract Service (www.cas.org).
  2. Time-weighted averages (TWAs) from the Australian Government’s agency Safe Work Australia. Units are parts-per-million (ppm) by volume and milligrams per cubic meter (mg/m<sup>3</sup>).
  3. Food and Agriculture Organization of the United Nations (2002). “Guidelines for regulating wood packaging material in international trade”, ISPM Pub. No. 15, FAO, Rome.

Common Toxic Industrial Chemicals (TICs)


A vast range of compounds are produced in very large quantities by industry as end products or as building blocks to form other chemicals. Among these are many toxic industrial chemicals, some of which are volatile and pose health risks to workers who are exposed to their vapors when they are transported. Table 2 lists some very common examples of volatile TICs.

Table2. Common toxic industrial chemicals, their uses and occupational exposure limits
Toxic Industrial Chemical TIC Name [CAS number1]Examples of toxic industrial chemical useTWA2
Benzene [71-43-2]

 

Precursor for many industrial compounds1 ppm [3.2 mg/m3]
Toluene [108-88-3]Solvent, synthetic precursor, fuel50 ppm [191 mg/m3]
Ethylbenzene [100-41-4]Intermediate in synthesis of styrene100 ppm [434 mg/m3]
Xylene [1339-30-7; 95-47-6; 106-42-3; 108-38-3]Solvent, cleaner, synthetic precursor80 ppm [350 mg/m3]
Styrene [100-42-5]Synthesis of polystyrene, etc.50 ppm [213 mg/m3]
Mesitylene (1,3,5-trimethylbenzene) [98-82-8]Solvent25 ppm [125 mg/m3]
1,3-Butadiene [106-99-0]Manufacture of synthetic rubber10 ppm [22 mg/m3]
Ammonia [7664-41-7]Fertilizers, synthesis, refrigeration25 ppm [17 mg/m3]
Phenol [108-95-2]Synthesis of plastics, pharmaceuticals, etc.1 ppm [4 mg/m3]
Acetaldehyde (ethanal) [75-07-0]Synthetic precursor20 ppm [36 mg/m3]
Dichloromethane (methylene chloride) [75-09-2]Solvent, cleaner50 ppm [174 mg/mv]
Chloroform (trichloromethane) [67-66-3]Solvent, cleaner, anesthetic2 ppm [10 mg/m3]
1,1-Dichloroethane (vinylidene chloride) [75-35-4]Synthetic precursor5 ppm [20 mg/m3]
Vinyl chloride (chloroethylene) [75-01-4]Manufacture of PVC5 ppm [13 mg/m3]
  1. ‘CAS number’ refers to the unique identifier assigned to a chemical compound by the American Chemical Society’s Chemical Abstract Service (www.cas.org).
  2. Time-weighted averages (TWAs) from the Australian Government’s agency Safe Work Australia. Units are parts-per-million (ppm) by volume and milligrams per cubic meter (mg/m3).

Toxic Chemicals and Fumigants Detection Technologies


There are a number of commercially available technologies for fumigant detection, several of which are compared in Table 3. They range from the simplicity of compound-specific colorimetric tubes to the complexity of gas chromatography.

Table 3 indicates that SIFT-MS offers the most comprehensive fumigant detection solution, especially in situations where it is not known which fumigants have been used. Moreover, the high sensitivity of SIFT-MS provides added confidence that carcinogenic fumigants will be detected at levels much lower than formal TWAs, thus avoiding unnecessary exposure.

CharacteristicColorimetric Tubes1Electronic Detectors2GC Detection3SIFT-MS
Breadth of analysisOne tube per fumigant testedLimited to a few fumigants per detectorAll fumigants, but this requires several analyses using different columnsAll fumigants. Easily configured for detection of any additional volatile organic compounds
SpecificityModerateLow to moderateHighHigh
SensitivityModerateModerateHighHigh
AccuracyModerateHighHighHigh
SpeedApprox. 1 minuteApprox. 1 minute>  15 minutes< 1 minute4
Required user skill levelLowLowHighLow
Consumable costs per sampleHighLowModerateLow
MaintenanceLowLow to moderateHighModerate
Sample preparationNoNoYesNo
  1. For example, Dräger and Kitagawa tubes.
  2. Performance varies depending on the type of detector, so generalizations have been made. Detectors in this class include infrared sensors, electronic noses and photoionization detectors (PIDs).
  3. Most often the detector is a mass spectrometer, but specific detectors may be used for certain compounds.For example, an electron capture detector (ECD) for halogenated compounds.
  4. SIFT-MS offers real-time detection and quantification of fumigants. See references 2-4 for more information about SIFT-MS

Conclusion


A diverse range of fumigants and TICs with a diverse range of chemical properties occur at harmful levels with concerningly high frequency. Until now there has not been a technology that can rapidly, accurately and simultaneously detect this range of threats. SIFT-MS, however, provides rapid and accurate broad-spectrum fumigant and TIC screening, combined with simplicity of operation.

For the first time, SIFT-MS provides workers and businesses in the shipping, freight and border security industries with a reliable and safe fumigant and TIC detection system.

 

References:

  1. X. Baur, B. Poschadel and L.T. Budnik (2010). “High frequency of fumigants and other toxic gases in imported freight containers—an underestimated occupational and community health risk”, Occup. Environ. Med., 67, 207-212.
  2. C.G. Freeman, M.J. McEwan (2002). “Rapid analysis of trace gases in complex mixtures using SIFT-MS”, Australian Journal of Chemistry, 55, 491-494.
  3. D. Smith, P. Spanel (2005). “Selected ion flow tube mass spectrometry for on-line trace gas analysis”, Mass Spectrometry Reviews, 24, 661-700.
  4. B.P. Prince, D.B. Milligan, M.J. McEwan (2010). “Application of selected ion flow tube mass spectrometry to real-time atmospheric monitoring”, Rapid Commun. Mass Spectrom., 2010, 24, 1763-1769.

 

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