Styrene is commonly used in the manufacture of polystyrene plastics and resins. Acute (short term) exposure to Styrene vapour in the workplace can cause irritation to the throat, nose and lungs. It can also cause neurological effects such as drowsiness, nausea and headaches. Chronic (long term) exposure affects the central nervous system, can cause depression, hearing loss and peripheral neuropathy. Styrene is readily absorbed and distributed throughout the body following exposure. It is considered to be a possible carcinogen.
The level of Styrene in the workplace should be no more than 100 parts per million (ppm) averaged over an 8-hour day. This is the maximum work exposure limit (WEL). Styrene is a flammable substance and eventually ends up in the air. Controlling vapour levels of Styrene depends on the manufacturing methods used, for example, the amount of resin used, whether one is using a non-atomising spray gun or not, whether gel coating is used, the curing rate, the size of the workroom etc. The greatest exposure is in industries using unsaturated polyester resins dissolved in Styrene. Dust from the fibres of glass reinforced grinding can also cause health problems; possible control measures are use of gloves and adequate local ventilation. Provided there is adequate controls in place there should be no damage to peoples’ health.
Styrene levels in the workplace should be monitored and maintained in accordance with the Control of Substances Hazardous to Health Regulations 2002. The external environment is regulated by the Pollution Prevention and Control Act 1999. European Directives regulating levels of Styrene include that which evaluates and controls the risks of substances known to be in the environment (793/93) and the Solvents Directive (99/13/EC). In October 2010, SIMPL (Safety In Manufacturing Plastics) initiative was set up and includes members from industry and HSE. Its aim is to help improve health and safety standards in the plastics industry. It provides help and support for companies involved in this industry.
Minimizing environmental exposure includes locating plants away from residential areas. Efficient capture systems should be used to disperse emissions and reduce ground-level concentrations. Styrene should not be stored next to other cargo with temperatures above 30 degrees celcius, otherwise the shelf life will be reduced and there would be an increase in the risk of polymerisation in the cargo tank. Tanks carrying or unloading Styrene polymer should not be exposed to chemicals that may react with it such as caustic soda, gasoline or oils. Minimizing exposure to human health includes providing good ventilation in the working area; this is critical to reduce inhalation. Gloves should be used and rollers with splash guards used to control droplets. Lids should always be replaced on containers. Ventilation may need to be supplemented with respiratory protective equipment. All should be done in accordance with COSH regulations. Facilities using styrene should have a response plan to include fire prevention, spill detection methods, environmental protection, emergency procedures and provisions for clean up in case of spills.