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New isocyanates testing regime at ChemCentre

New isocyanates testing regime at ChemCentre

Date Published: 29-Apr-16

A new sampling regime will enable ChemCentre to test air for isocyanates, a potential occupational health concern.
Isocyanates are widely used in industry to produce polyurethane of various forms, from coatings and foams to rigid structures. Production of isocyanates is expected to reach 18 million tonnes in 2016, with the top three consumers being the transportation, furniture and construction industries.

Isocyanate exposure can lead to sensitisation, contact dermatitis and occupational asthma. Methylenebis (phenylisocyanate) (MDI) and toluene diisocyanate (TDI) are classified according to the GHS (Globally Harmonised System) in Carcinogenicity Category 2 – suspected cancer causing agents.
 
ChemCentre’s Occupational Health Investigations team presented on the use of the testing regime – SKC ISO-CHEK filters – at the December 2015 Australian Institute of Occupational Hygienists (AIOH) conference.
 
Traditionally samples are either collected via a solvent impinger, containing a derivatising agent (a chemical which can change the structure of another chemical allowing it to be more easily analysed), or a single layer 1-(2-pyridyl)piperazine (PP) coated filter. These traditional techniques are prone to technical issues; for example, the impinger samples may spill during collection and transport or may evaporate. The single layer filter may underestimate the true concentration of isocyanate exposure as the aerosol produced may not be effectively trapped on the single sized filter.
 
The sampling technique employed by the OHI team utilises the SKC ISO-CHEK system. This sampling gear consists of dual filters. The front filter collects the isocyanate in aerosol form and the back coated filter collects the vapour form. After sampling, the top filter is removed and placed in a derivatising solution; the remaining back filter is left intact. The front and back of the filters are then analysed for derivatised isocyanates by Ultra Performance Liquid Chromatography (UPLC).
 
ChemCentre can now detect about ten times lower than the short term exposure limit (STEL) of certain isocyanates (see table below).
 
ChemCentre is also developing a method to analyse isocyanate metabolites in biological samples. This is another technique widely used within industry to monitor personal exposure, but is not currently offered in WA.

To enquire about the isocyanate testing services, or any of the occupational health services, contact OccHealth@chemcentre.wa.gov.au.

Compound Detection Limit (mg/m3) STEL
(mg/m3)
2,4-Toluene Diisocyanate (TDI) 0.005 0.07
2,6-Toluene Diisocyanate (TDI) 0.005 0.07
Hexamethylene Diisocyanate (HDI) 0.005 0.07
Methylene bis-cyclohexylisocyanate (HMDI) 0.005 0.07
Isophorone Diisocyanate (IPDI) 0.005 0.07
Methylenebis(phenyl isocyanate) (MDI) 0.005 0.07

Photo credit: Envirocare, UK

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