CAW National Council 4000
Occupational Health and Safety

Hazardous Substances:  Plastics

The term “plastic” covers a wide range of synthetic polymer materials. What they have in common is that they are all made by
joining together or “polymerizing” a bunch of molecules (monomers). For example, polystyrene is a polymer of styrene, polyvinyl
chloride (PVC) is a polymer of vinyl chloride and ABS is a co-polymere of acrylonitrile, butadiene and styrene. Chemical companies
usually sell plastics to product and parts manufacturers in an unfinished form known as “resin”, in the form of solid granules, pellets,
powder and sometimes as liquids. The resins are moulded, pressed or extruded into their final form. Because they are directly
exposed to higher concentrations of monomers and additives, workers in chemical plants who make the plastic monomers and
polymerize them to make resins face hazards that are somewhat different from those faced by those who form the final plastic
products from resin. Nevertheless, your health may be affected by the polymer resin itself, by monomer residues remaining in the
resin, by chemicals added to the plastic to make it more flexible, stable or flame retardant, or by colouring agents. These substances
may also be released to the air when the plastics are heated.

Health Hazards from Plastics Processing

When plastics are heated to form final products, monomers, additives and degradation products can be released. Small amounts of
these may also be present in the resins before heating. They can affect the health of workers who use, clean or maintain the
processing equipment. The table on the following page shows what these substances are and what types of effects they can have
on your health.


Enclose process
Local exhaust ventilation
Personal protection where appropriate, depending on type of resin used.

Some resins release carcinogenic degradation products. All carcinogens should be eliminated from the workplace wherever possible
as even minimal amounts can initiate the uncontrollable growth of abnormal cells.


ACGIH TLVs for monomers, additives and degradation products:

Acrolein 0.23 mg/m3 (0.1 ppm)
Acrylonitrile 4.3 mg/m3(2 ppm)
Benzene 32 mg/m3(10 ppm), to be changed to 0.96 mg/m3 (0.3 ppm)
Butadiene 4.4 mg/m3(2 ppm)
Carbon monoxide 29 mg/m3 (25 ppm)
Carbonyl fluoride 5.4 mg/m3 (2 ppm)
Di-(2-ethylhexyl)phthalate 5 mg/m3
Epichlorohydrin 7.6 mg/m3 (2 ppm), to be changed to 1.0 mg/m3 (0.5 ppm)
Formaldehyde 0.37 mg/m3(0.3 ppm), U.S. NIOSH recommendation (0.016 ppm)
Methyl methacrylate 410 mg/m3(100ppm)
Styrene 213 mg/m3 (50 ppm), to be changed to 85 mg/m3 (20 ppm)
Toluene 188 mg/m3(50 ppm)
Vinyl chloride 13 mg/m3 (5 ppm)

Source:  CAW Health, Safety & Environment Department