Emission of toxic sulfur gases from polymers coming in contact with food products and with infants

Abstract

The toxicity of the constituants (polymers and additives) of polymer materials is well documented. However, there is relatively little information concerning the gaseous compounds evolved from these materials with the exception of extreme conditions such as high temperature and fire conditions. Given the fact that non-negligible quantities of carbon sulfide, CS 2 , are used in the manufacturing of polymers such as rubber compounds during their vulcanization process, we tried to evaluate the emission of sulfur gases from rubber samples used in domestic applications in the conditions of their common temperature conditions (from ambient up to approximately 150°C). Experimental Gaseous emission from rubber compoundsTwo main categories of samples were studied. 1 o -rubber gaskets coming in contact with food products (e.g. in coffee machines, pressure cooker, etc.) and 2 o -rubber teats and related items made out of latex compounds coming into direct contact with infants, thereafter designated as teats. Measuring conditions and analytical methodsThe samples were taken from rubber items bought in department stores. A known quantity of the order of 1 g was placed in a 20 mL vial which was then sealed. The sample was equilibrated with its gas phase at 80°C for a period of 20 minutes. The head space, HS, i.e. the gaseous phase, was then injected into three types of analyzers: 1) a head space sampler, HS 40 XL (Perkin Elmer) coupled to a gas phase chromatograph, Autosampler XL (Perkin Elmer), the HS/GC technique;2) a mass spectrometer, Thermolab (TA Instruments), the HS/MS technique;3) an infra-red spectrometer, Nicolet 510 FTIR, equipped with a gas cell, the HS/FTIR technique.Complementary measurements were performed using the coupling between a pyrolyzer, Pyroprobe 200 from CDS Instruments, and the mass spectrometer, the PY/MS technique. In this case, the polymer sample was heated directly in the pyrolyzer and the evolved gas phase analyzed with the MS.The infra-red spectra of all the solid samples were also measured in the diamond-ATR mode (Golden Gate accessory from Graseby-Specac) in order to identify their class of polymers. ResultsWe examined 11 samples of type 1 (gaskets, including 3 septa used in the laboratory) and 4 samples of type 2 (latex teats). The infra-red spectra indicate that all samples belong to the class of polyolefinic polymers (polyisoprene, polybutadiene) some of which obviously being copolymers and/or containing either a cellulose load (samples 1, 3, 6a, 21 and 23), or a mineral load, (as sample 6b probably containing Abstract. The analysis of the volatiles evolved from a number of polymer samples commonly used in domestic applications show that carbon disulfide, CS 2 , and carbonyl sulfide, COS, are emitted in the lower range of temperatures, i.e. from room temperature up to 150°C. Emission of COS in the ppm range was also monitored from materials used in the fabrication of the teats for baby's feeding bottles and from similar devices. Given the lack of legal tolerance limits on the toxicity of C...

Carbonyl Sulfide: A Review of Its Chemistry and Properties

“…13 Bhatia 14 reports that carbonyl sulfide concentrations greater than 20 mg/L can cause irritation in the upper human respiratory system. Houriet and Louvier 15 classify carbonyl sulfide as a substance that belongs in toxicity class 2 with a threshold toxicity value of 23 ppm (mass/mass) for mammals. As of 2002, however, the U.S. Environmental Protection Agency (EPA) has neither established a reference dose for chronic oral exposure (RfD) or a reference concentration for chronic inhalation exposure (RfC) for the compound nor classified it with respect to its potential carcinogenicity.…”

“…Such polymers include the materials used in the fabrication of the nipples for baby feeding bottles. This led to the suggestion of imposed tolerance limits on the toxicity of carbonyl sulfide …”