Research on PSS
Incidence of PSS
The earliest studies of platinum salt sensitivity (PSS) within PGM refinery workers, published in the 1940s and 1950s, report prevalences of up to and exceeding 50%. Over time, incidence and prevalence of PSS have progressively decreased. The most recent studies of PSS published in 2016 and 2020 report incidence rates of 2.4 and 1.5 cases per 100 person-years, respectively. Data collected by IPA from its member companies show the number of cases of PSS and the incidence rate have continued to decrease since 2010.
Epidemiology of Platinum Salt Sensitivity (PSS)
Various epidemiology studies of platinum salt sensitivity (PSS) have been published, exploring which Pt substances have the potential to cause sensitisation, investigating the relationship between magnitude of exposure and risk of becoming sensitised, and potential contributing factors such as smoking and atopy.
The industry-sponsored epidemiology studies provide the best insight into the exposure-risk relationship for chloroplatinates and PSS. There remain multiple uncertainties about the true exposure-risk relationship that could not be addressed in these retrospective studies, and because the incidence of PSS has now decreased to such a low level it is unlikely that any conceivably viable future epidemiology study of PSS would provide significant new insight.
There may be further advances in the understanding of PSS and Type I hypersensitivity of the respiratory tract more generally that provide greater confidence in what the true exposure-response relationship is likely to be, and this may influence target levels for occupational exposure controls. See the attached for further information.
Sufficient evidence is available now, though, to draw reasonable science-driven conclusions on exposure levels expected to be protective (see Occupational Exposure Limit and Voluntary Guideline Value).
Chemical screening test for sensitisation potential
Platinum Salt Sensitivity is associated almost exclusively with complex halogenated platinum substances, of which the chloroplatinates and the pharmaceutical platin chemotherapeutics are by far the most common. In conducting Research & Development activities on platinum compounds, whether a novel platinum compound might have the potential to cause respiratory sensitisation will be an important consideration.
IPA, in collaboration with the University of Wisconsin, demonstrated the Direct Peptide Reactivity Assay (DPRA) was able to correctly identify a selection of platinum substances as either having or not having sensitisation potential. Although the DPRA is only a screening assay and further work may be required to judge its broader performance with metal compounds, this initial research provides optimism for its utility in screening novel platinum compounds.
Further information can be found in the attached Screening tests for chemical sensitisation potential – Direct Peptide Reactivity Assay (DPRA).