Plastics are polymers (poly-many, meros-part), a long chain of molecules that is made of repeating parts, called monomers. These can be natural or synthetic. All plastics are polymers, all polymers not plastics, and the term typically refers to man-made thermoplastic polymers (fibre, elastomer, thermoset) obtained from hydrocarbon sources like petroleum. About four per cent of the oil extracted in the world is used to produce all the plastics used in everyday life.1 About one third of the oil is used in the supply of all the plastic packaging needed by a modern society.2 The amount of oil used may look small when shown in percentage but when converted it is billions of tonnes.

But why are plastics the preferred materials? First, they are lightweight for shipping and storage. Two, large industries have large subsidies to extract oil and gas, and plastics are the only offer as raw material for manufacturing industries - hence there is an in built subsidy to produce plastic globally.

The other thrust that plastic got was the rapid decline in forests
that provided wood and paper, which plastics readily displaced. Since plastics are malleable for design purposes (e.g. electronics, clothes, bottles, packaging, etc..), they are therefore cheap and dispensable. But plastics are not biodegradable and are responsible for a major civic crisis in cities and countryside. India has a high consumption of plastics and nearly 50 per cent of it is used in the packaging industry (see table: How much plastic do we consume?)

How much plastic do we consume?

Polymers are the basic building materials of all plastics. But they would be useless without additives. Additives or modifiers, make up to 60 per cent of the volume of a polymer. There are many types of additives. Ordinarily the polymer may be benign but the modifiers likely will not be. Additives are added to the polymers to give them their inherent qualities. The additives could include colourants for coloured plastics, foaming agents for styrofoam or thermocol plasticisers, for specific physical properties like flexibility, used in teethers and toys (see box: Toxic toys).

Although they help give the plastic the desired physical properties, additives make them dangerous for being used, as they are typically poorly bonded with the polymers and tend to leach out. They can then reach the human body when we chew on a teether, use tubes in hospitals, allow our food to come in touch with some plastics or burn them. So given this heady cocktail of chemicals that goes into making a simple plastic bag, disposing it in fields or rivers and streams means that these chemicals will be released slowly into the soil, water and reach into the food cycle. Disposal of plastics is an extremely controversial issue. Landfill, or large open pits in which plastic of all types are dumped, ensures that leaching of modifiers takes place. Burning is possibly even graver since it leads to the formation of dioxins, especially in the case of PVC and PU. Dioxins are also produced by incineration of hospital waste, which also contains PVC. PVC causes more hazardous by-products than any other plastic. The hazard stems from high content of chlorine in PVC and also large amounts used in manufacturing it. Toxic organochlorine (OC) by-products are formed and chlorination process create entirely new toxic effects. Some OCs interfere with hormone function and the toxicity increases with each additional chlorine substitute. Incineration burning of plastics also leads to release of polychlorinated biphenyls (PCB’s), which have now been incriminated as causing infertility in men. Young Danes have reported exceptionally low sperm counts compared to the previous generations, testicular cancer has increased in incidence by 55 per cent between 1979 and 1991 in England and Wales, fewer boys are being borne in Seveso, Italy, where toxic dioxin was released, some girls are achieving puberty earlier than others (see Briefs: PCB’s incriminated,).3 Chemicals like lead used in the production of plastics also impacts intelligence. Burning of plastics in particular cause allergic epidemic such as asthma and cases of contact allergies are increasing.

Hormone disruption, cancer, increased breathing disorders and systemic disorders have been associated in people exposed to fumes of burning plastics. PVC is considered to be the biggest villain among the plastics family. Because when the developed countries, and currently the developing countries like India incinerate and burn it in open bins it produces dioxins and furans - the most subtle yet menacing among all chemicals. Incineration and energy recovery are highly toxic and polluting processes. Even the plastic industry knows that plastic cannot be recycled more than 3-4 times. This means that with every downcycling cycle, there are some plastics that are too weak to be reprocessed again. Typically, such plastics will end up dumped in the ground or the seas. This is just not good for the image of the plastics industry, because when people see all this plastic, they ask questions about unsustainable consumption. To stop this poor image of themselves, the plastic industry is now suggesting energy recovery from them through various kinds of technologies that require burning of the waste, such as incineration. However, the health and environmental costs of these are just too great. Incineration is a highly toxic process for a number of reasons. Firstly, as plastics burn, some of them, such as PVC, polyurethane (PU) etc. release dioxins, which are amongst the most toxic chemicals in the world. They have been known to lead to not only cancers, but also endocrine disruption and reproductive disorders. Increasingly, incinerators are being linked the birth of defective babies. When plastics contain lead and cadmium, these are found in the ash, which later either leaches into the ground water through landfills or flies around, entering out bodies in other ways. Lead affects the neurotoxic, impacting the intelligence system, especially of children. Cadmium can severely harm the kidneys. Mercury evaporates and reaches through the air. It is known to cause serious damage to the nervous system. From landfills too PVC can leach out its additives, and recycling is difficult.

Bisphenol A is used in the manufacture of linings for food cans and lids, and is the main ingredient in polycarbonate plastic bottles. Bisphenol A is an endocrine disruptor — it can imitate the female hormone, and low level exposures of developing female mice have been shown to advance their puberty. Plasticisers have also been linked to the high incidence of autism found amongst the children of Brick Township, New Jersey,USA (see box: plasticisers and autism).