Polystyrene is used to make

• coffee cups
• soup bowls and salad boxes
• foam egg cartons; produce & meat trays
• disposable utensils
• packing “peanuts”
• foam inserts that cushion new appliances and electronics
• television and computer cabinets
• compact disc “jewel boxes” and audiocassette cases

It is also used as a building material, with electrical appliances (light switches and plates), and in other household items.

Derived from petroleum and natural gas by-products, styrene helps create thousands of remarkably strong, flexible, and light-weight products that represent a vital part of our health, safety and well-being. Probably the most recognizable material is polystyrene, often encountered as expanded polystyrene foam (EPS). Other styrene-based materials include acrylonitrile-butadiene styrene (ABS), styrene-acrylonitrile (SAN), styrene-butadiene rubber (SBR), and unsaturated polyester resin (UPR), which is better known as fiberglass. The styrene information and research center

Thousands of small units of styrene, called monomers, link together to form large molecules of polystyrene by a process called polymerisation.

Expanded polystyrene starts as small spherical beads with a typical diameter of 0.5-1.5mm. They contain an expanding agent;When the beads are heated with steam, the agent starts to boil, the polymer softens and the beads expand to about forty times their initial size. After a maturing period to equilibrate temperature and pressure, the pre-foamed beads, which now have a closed cellular foam structure, are placed in a mould and again reheated with steam. The mould can be designed to meet any requirements of the customer. The pre-foamed beads expand further, completely fill the mould cavity and fuse together. When moulded, nearly all the volume of the EPS foam (in fact 98%) is air. This is what makes EPS so lightweight and buoyant.

Taken from the styromelt website

It contains styrene which is according to some is  a toxic carcinogen that  leaches  from the container into the contents – your coffee for example – try this site for an in depth discussion of the issue.

The styrene information and research center ( representing the industy) has this to say on the subject “in 1989 OSHA and the U.S. Centers for Disease Control and Prevention’s National Institute for Occupational Safety and Health (NIOSH) reviewed the health data on styrene and concluded that styrene does not pose any cancer risk. An international panel of experts from the 12-nation European Community reached the same conclusion in 1988. Canada decided in 1994 that styrene posed no carcinogenic risk. A draft 1996 risk assessment of styrene by the Health & Safety Executive of the United Kingdom also concluded that styrene does not pose a carcinogenic threat.

In 1987, the International Agency for Research on Cancer (IARC) upgraded styrene’s classification to a “possible” human carcinogen. Many scientists have disputed this action because it was not based on new cancer data, but resulted from changes in the criteria for IARC classifications. ”

However it is on the hazardous substances list

REASON FOR CITATION
* Styrene Monomer is on the Hazardous Substance List because it
is regulated by OSHA and cited by ACGIH, NIOSH, DOT, DEP, NFPA
and EPA.
* This chemical is also on the Special Health Hazard Substance
List because it is a MUTAGEN, FLAMMABLE, and REACTIVE.

Safe levels of exposure have to be maintained and OSHA  also state “Health effects of styrene include irritation of the skin, eyes, and the upper respiratory tract. Acute exposure may also result in gastrointestinal effects. Chronic exposure affects the central nervous system showing symptoms such as depression, headache, fatigue, weakness, and may cause minor effects on kidney function. ”

Styrene is listed by the EU as a potential endocrine disruptor.

As with all plastics it  lasts an incredibly long time. Consequently plastic cups and clam shells can be seen littering the environment the world over.

Tiny polystyrene globules from degraded products mix forever with the sand.

In the old days in couldnt be recyled; now it can but facilities are limited. Though of course that may well change in the future.

As with all plastic polystyrene does not biodegrade. Instead it hangs around for years creating everlasting litter and problomatic pollution. BUT the boffs are working on the problem and here are their solutions

Recycling

Polystyrene is difficult to recycle. Difficult but not impossible …

For those of you who insist on using polystyrene cups you can out more about recycling them here.

For the other stuff there is a  process for recycling  polystyrene that uses  the styromelt system.

Polystyrene and the OZONE LAYER

There are other issues with polystyrene the expanding agent that causes the styrene to puff up affects the ozone layer

However, despite EPF’s popularity and unique features, it has recently come under attack because of the gaseous methane derivatives—chlorofluorocarbons (CFCs)—used to foam it. CFCs are inert, and harmless to humans and the environment upon their release. However, long after their first use, scientists realized that CFCs contribute to the depletion of the ozone layer as they decompose. The ozone layer is a layer of the atmosphere that protects the earth against harmful ultraviolet rays from the sun. In 1988 representatives from 31 nations signed the Montreal Protocol, a treaty with which they resolved to halve CFC production by 1998. This agreement brought EPF to the world’s consciousness as a threat to the ozone layer. While foam packaging is responsible for less than three percent of the CFCs being released into the atmosphere, EPF reduction has been targeted as a way to lower CFC levels, and new technology that explores ways to produce EPF without CFCs has flourished.

see  answers website

the expanding agent now used is “a pure hydrocarbon, which does not contain any halogens and does not damage the earth’s protective ozone layer.” Taken from the styromelt website

However environmentalists disagree see rebuttal

As with all plastic the arguments are split between the producers and the environmentalists and can be very basically summarised as follows: superlative product with a myriad of wonderful applications, recyclable and above all completely inert and safe as opposed to consumerism gone mad and leacher of carcinogenic chemicals.

But whichever your school of thought all agree that its looks nasty, is polluting the environment and lasts a very long time. So lets not use it to make throw away items.