It is difficult to imagine our lives without plastics – they are an indispensible part of the mass production and storage of our food, our smartphone and computer-dependent living, and have helped revolutionise medicine with the development of plastic replacement body parts, syringes and intravenous fluid bags. Once mass production of plastics began during the 1940s and 1950s, it was possible to manufacture consumer goods on an affordable and grand scale, resulting in the rise of the single use plastic bag and drink bottle with little provision for appropriate disposal or recycling. It is now clear that this plastic-fuelled revolution has come at a price, with toxins from plastic entering our oceans, rivers and groundwater, poisoning our already fragile food chain, and threatening the health and lives of humans and animals across the globe.
What toxins are in plastic?
We have summarised what goes into the 7 most commonly used plastic types at the end of this article, each of which may be identified by the recycling symbol and #1-7 numbering system.
Most plastics are made from hydrocarbon molecules obtained from refining petroleum or natural gas, where carbon-based monomers are extracted, forming the building blocks of plastics. Monomers are processed to form polymers or copolymers – chains of monomers of the same or different types joined together. These are mixed with various additives, including antioxidants, plasticisers and flame retardants, to provide additional properties. By combining different monomers and additives, it is possible to obtain an enormous range of plastics with varied properties.
Plastics were once considered inert, non-reactive substances, but it is now understood that this is not the case. The process of polymerisation which creates plastic is rarely complete, meaning that unbound monomers, many of which are toxic in their free state, are free to leach from the plastic. Additives, too, are not always strongly bound to the polymer, and may leach from the plastic into food and drink (Read about it here.).
It is now understood that leaching of toxic monomers can be accelerated by exposure to UV radiation (sunlight), microwaves, moist heat, scratching and possibly by freezing. Polymers, too, may undergo a change in their chemical structure under these ‘stressed’ conditions and gain oestrogenic activity (Read about it here.). This is something few people consider when using plastic containers to store food and drink, heating food in the microwave, or exposing containers to sunlight.
Chemicals of concern that leach from plastic include the following
Oestrogenic molecules, sometimes termed xenoestrogens, are potentially present in all plastics ( Read about it here. ) but of particular concern are phthalates in PVC, #3, bisphenol A in polycarbonates, #7, and the now banned PCBs which are present in some plastics made before 1979 ( Read about it here. ). Xenoestrogens are known to have effects including abnormal development of reproductive organs, reduced fertility due to sperm and egg abnormalities, increased incidence of gonadal intersex, and altered sex ratios ( Read about it here. ). The steadily increasing incidence of breast cancer in women in western cultures and industrialised countries has been linked to prolonged exposure to oestrogen via an early menarche and late menopause. There is concern that this could be at least in part due to increased exposure to xenoestrogens. Of particular concern was the demonstration that bisphenol A was able to induce neoplastic changes (transformation into cancer) in breast epithelial cells in tissue culture studies ( Read about it here. ). Bisphenol A is commonly used to manufacture baby bottles, coats thermal paper receipts and lines most tinned foods. Bisphenol A is found in the urine of most people today – in a study carried out in 2004, BPA was found in the urine of 93% of children and adults studied ( Read about it here. ). In one study it was shown that use of a hand sanitiser before handling a thermal receipt and eating food enhanced absorption of BPA into the bloodstream ( Read about it here.).
The vinyl chloride monomer from polyvinyl choride, PVC, #3, is both highly toxic and carcinogenic. It is responsible for the ‘new car smell’, and is widely used in construction, clothing and furniture ( Read about it here.);
The monomer styrene, which may be present at up to 1% in polystyrene, PS, #6, which is commonly used in takeaway hot food and hot drink containers, is toxic, mutagenic (damages DNA) and possibly carcinogenic (Read about it here.);
- Bisphenol S, which has to some extent replaced bisphenol A in some polycarbonate #7 plastics because of safety concerns, has been linked to abnormal neurological development in the hypothalamus (a region of the brain which regulates many body functions, including many endocrine functions) of fish at very low doses, resulting in hyperactivity (Read about it here.).
- In addition to its oestrogenic effects, bisphenol A has been linked with an increased risk of cardiovascular disease, diabetes and liver enzyme abnormalities (Read about it here.), and possibly obesity in children (Read about it here.).
- Other potentially toxic additives include the toxic metal antimony in PET plastic, and lead, cadmium and other toxic heavy metals in PVC. The flame retardants such as the polybrominated diphenyl ethers (PBDE) are known toxins with neurobehavioural and endocrine disrupting effects (Read about it here.), and are used in a range of plastics.
Isn’t most plastic recycled?
Approximately 110 million tons of plastic are consumed worldwide each year (Read it here ). Despite the fact that we have the ability to recycle much of our plastic, the world’s recycling rate is estimated to be a dismal 6.5%. Most of the remainder goes to landfill, where it may remain intact for hundreds of years, leaching toxins into groundwater, while a good proportion of it makes its way into rivers and oceans (Read about it here.). Recent studies estimate that 8 million tons of plastic goes into our oceans each year (Read about it here. ).
The effects of plastic waste on wildlife and the environment
It is estimated that around 100,000 animals die each year from becoming entangled in or ingesting plastic, where it lodges in their digestive tracts, causing starvation (Read about it here.).
In the 70 years or so since plastic has been mass-produced, sufficient amounts have been washed into the ocean to form the Great Pacific Garbage Patch, North Atlantic Garbage Patch and the Indian Ocean Garbage Patch (Read about it here.) - huge swathes of plastics trapped in the upper layers of the major ocean gyres, the great circular marine currents. Much of this plastic is eventually broken down to microplastics, ranging in size from microscopic to particles of 5mm in diameter, which are small enough to be ingested by all stages of the food chain, causing still unknown effects. A recent study on the Great Barrier Reef showed that corals take in pieces of microplastic which then lodge in their digestive tracts and cannot be expelled, further adding to the pressures on this already endangered ecosystem (Read about it here.).
Apart from the physical effects of indigestible plastics on the health of wildlife, oestrogenic compounds and other toxins present in the ingested plastics may cause systemic harm to the animals which ingest them, resulting in reduced fertility and increasing susceptibility to disease, adding to the risk of food chain collapse.
In addition to the toxins present in plastics, it is now becoming clear that plastics adsorb and concentrate organic pollutants, acting as toxic reservoirs of persistent organic pollutants like PCBs, dioxins and the toxic DDT derivative DDE, since these toxins adhere to plastics and become concentrated (Read about it here.), making microplastics even more toxic, and further adding to the risk of harmful effects on wildlife. It has now been shown that fish that ingest plastics which have adsorbed toxins from the marine environment at similar concentrations to those found in the Great Pacific Garbage patch, suffer liver toxicity and other pathologies, partially attributable to the physical effect of the plastic on the digestive tract, and partially due to the toxins consumed. (Read about it here.).
Clearly, plastic pollution jeopardises the health of our oceans, in addition to our own health, adding further severe strain to our already fragile ecosystems.
What happened to reduce, reuse, recycle?
Not much reduction
The worst offenders, single use plastic bags and single use water bottle containers, are the obvious first targets when aiming to reduce the overall load of plastic waste in the environment.
Plastic bags and water bottle containers have been banned in a small number of cities and countries throughout the world (Read it here; and here. Despite this, it is estimated that 1 trillion plastic bags are used and discarded each year, and Australia is responsible for approximately 4 billion of these. In the USA only 30% of PET plastic (most commonly used for single use water bottles) was recycled in 2013, with much lower rates of recycling in most of the rest of the world.
Polystyrene containers are another clear target and have already been banned in some states of the USA because of the difficulty in disposing of polystyrene waste. Australians throw out over 40,000 tons of polystyrene each year, of which less than 7% is recycled (Read it here ). It is virtually non biodegradable, contains toxic styrene and is used to dispense hot foods which are likely to increase leaching into the food and drink consumed (Read it here ).
Not much recycling
The poor rate of recycling worldwide (around 6.5% by some estimates) is considered to be partly due to the difficulty of sorting plastics into their different types, as different processes are required for different plastics, and due to the lack of recycling facilities. Further, it is not financially viable to recycle some plastics.
In some places, reverse vending machines give money back for plastic bottles and aluminium cans (Read it here ), and in Australia, container deposit schemes operate in SA and the NT, which boasts a container return rate of almost 80% (Read it here ).
It’s clear that given the opportunity and/or a financial incentive, plastic can be recycled at a higher rate. Another strategy is to increase the price of plastic to reflect its true health and environmental cost. This would it more profitable to recycle plastic and make it less financially competitive when compared to paper, cloth, glass and metal packaging.
What you can do
For the sake of your own health, that of your family and the environment, cut down your own use of, and exposure to, plastic. There is plenty of information about how this can be done: see 100 Steps to a Plastic Free Life ; 20 ways to give up plastic and the toxins in it .
It doesn’t take long to see that the bulk of household plastic waste is generated by purchasing mass produced food and drink – when shopping in supermarkets we even put fresh produce into plastic bags. Buying in bulk, using paper or cloth bags for fresh produce, eliminating packaged and canned foods, shopping at farmers’ markets, growing some of your own produce, and wrapping wet waste in newspaper so you can get rid of your bin liner, are just some of the ways people have drastically reduced their plastic waste.
At Mokosh, our packaging is glass (our certified organic skin care products) and recycled paper (our certified organic bar soaps). We reject the cheaper plastic options because we don't want to add to the amount of toxic plastic polluting the earth, and because we don't want our products contaminated by leaching of toxins into our products.
If you are already an anti-plastic activist, how have you reduced plastic use in your life, and have you managed to influence others to make the change?
How can we start to turn the plastic tide?
Getting to know the 7 plastics...
#1 – PET, PETE (polyethylene terephthalate)
PET is generally a transparent plastic, commonly used for water and soft drink bottles, and some foods. Because it has been considered relatively insert, it is considered safe by most authorities. However, a recent study showed that some PET containers, although BPA free, leach oestrogenic compounds ( Read it here ). However, leaching of these compounds is inconsistent between PET manufacturers, most likely because of inconsistencies in the types of additives and different processes used to make PET. Of note is that when stressed by heat or UV radiation in the above study, all PET containers leached oestrogenic substances. Another concern with PET has been the potential leaching of antimony oxide, which is used as a catalyst in the manufacture of PET and incorporated in small amounts into the plastic. However, most would consider the amounts leaked to be well below what are deemed toxic levels ( Read it here ).
#2 – HDPE (high density polyethylene)
HDPE is a flexible plastic that is usually opaque, and used to package a variety of food and cleaning products and to make outdoor furniture. It is another plastic that has traditionally been considered safe. However, as shown in the study already mentioned, oestrogenic compounds leach from some forms of this plastic, and stressors, particularly UV light, caused leaching of oestrogenic compounds from a sample that otherwise did not. Despite their generally low inherent toxicity, HDPE and LDPE as well as PP (polypropylene) are the plastics most efficient at adsorbing toxic pollutants in aqueous environments ( Read it here ).
#3 PVC (polyvinyl chloride)
PVC comes in both rigid and flexible forms. The rigid form is used to make water and waste pipes, rigid bottles and credit cards. The flexible form of PVC contains plasticisers, typically the phthalates, and is used to make some forms of cling film, inflatable products, vinyl flooring and intravenous fluid bags. Some of the phthalates used as plasticisers are known to have oestrogenic activity, and some forms have been banned in Europe and the USA. In addition, heat stabilisers may be added to both forms of PVC, including lead, cadmium and other toxic heavy metals for which there are concerns about effects on human health. In some countries these are being phased out for health reasons, and substituted with non-heavy metal substitutes. ( Read it here ).
PVC is made of monomers of vinyl chloride, which is toxic to a number of organ systems. As there is almost always some free vinyl chloride in PVC, small amounts leach into the air (the source of the new car smell from PVC car lining), and into food and drink containers.
Incineration of PVCs may result in the release of the potent carcinogen, dioxin, although this can be reduced by burning in optimal temperature and oxygen conditions ( Read it here ).
#4 LDPE (low density polyethylene)
Like HDPE, low density polyethylene is made from ethylene monomers, but its molecules are more branched, and therefore weaker and less dense than HDPE. It is used to make plastic bags, 6-pack rings, and to line cardboard cartons to make them waterproof. In the study previously mentioned, like HDPE, some LDPE products leached oestrogenic compounds, whereas others did so only after stressing with UV light ( Read it here ). Note that HDPE and LDPE, together with PP, are the plastics most efficient at adsorbing toxic pollutants in aqueous environments ( Read it here ).
#5 PP (polypropylene)
Used widely including for product labels, textiles, carpets, drinking straws and product packaging. Generally considered a safe plastic, although oestrogenic activity was demonstrated in some PP products in the previously mentioned study ( Read it here ). Polypropylene, along with HDPE and LDPE, is one of the plastics most absorbent of organic pollutants ( Read it here ).
#6 PS (polystyrene)
Also known as Styrofoam, PS is used to make disposable coffee cups, plates and cutlery, take-away containers, meat trays, food packaging, CD containers and insulation. Polystyrene may be in solid or foamed form, and is made from ethylbenzene, which is obtained from benzene ( Read it here ). Athough polystyrene is relatively inert, it contains up to 1% of the monomer styrene, which leaches from the container on exposure to heat and following prolonged contact. ( Read it here ). When ingested or inhaled, the monomer styrene is considered toxic, mutagenic and possibly carcinogenic ( Read it here ).
#7 – Other, including Polycarbonates
Polycarbonates are made from polymers containing carbonate groups, predominantly by the reaction between bisphenol A and phosgene. It is used to make baby bottles, large containers for water dispensers, spectacle lenses, to line food cans and to coat paper receipts. The major concern with polycarbonate plastics is the leaching into food and drink of free bisphenol A, which seems to be enhanced by heat. Bisphenol A is an endocrine disruptor that is considered to be particularly dangerous to developing foetuses and babies, with links to cancer, obesity, anxiety and hyperactivity. So much so, that the FDA banned the use of bisphenol A in baby bottles and cups. A replacement, bisphenol-S, has to some extent replaced bisphenol A in products labelled BPA-free, but a recent study showed that both bisphenol A and bisphenol S have adverse effects on development of the nervous system in an experimental system ( Read it here ) observable hyperactivity in zebrafish exposed to both compounds during gestation.