Hazards of Polymers

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Environmental Hazards of Polymers

Introduction

In today's world, life without plastics is incomprehensible. That is very true, plastics are

extremely necessary in our modern society, but some of the current use and misuse is not

sustainable. A more sustainable use of plastics can be achieved by many measures. There is a

large potential for reducing the per capita use in the industrialized world, for instance by

eliminating excessive packaging material and practicing material reduction whenever possible.

By developing more plastics based on bio-based raw materials, the great dependence on non-

renewable crude oil and the environmental consequences of crude oil extraction and refining, as

well as the contribution to global warming during the end of life phase, can be decreased.

Persistence is desired in many applications for long term use, but for short term and single use

applications, especially in the packaging sector, the use and further development of

biodegradable plastic materials that are fully degradable in the natural environment, are

important. Recycling of plastics involve problems since a homogeneous fraction is needed for a

similar grade end-product, but the recycling could be facilitated by practicing Eco design for

recyclability and systems for collecting recyclable fractions. Increased recovery (mechanical,

chemical or energy recovery) when possible, saves resources and decreases the area needed for

landfill. Global action and strong measures to reduce littering are essential to protect our oceans,

coastlines, fresh water ecosystems and also our terrestrial environment.

Polymers are substances whose molecules have high molar masses and are composed of a large

number of repeating units. There are both naturally occurring and synthetic polymers. Among

naturally occurring polymers are proteins, starches, cellulose, and latex. Synthetic polymers are

produced commercially on a very large scale and have a wide range of properties and uses. The

materials commonly called plastics are all synthetic polymers.Polymers are formed by chemicalreactions in which a large number of molecules called monomers are joined sequentially,

forming a chain. In many polymers, only one monomer is used. In others, two or three different

monomers may be combined.

Types

There are different types of polymers but generally polymers are classified into two types that

are:

Natural Polymers Synthetic Polymers

Synthetic polymers are further classified into three main classes that are:

Thermosets


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Thermoplastics Elastomers

Thermosets

Those polymers that are not be converted or reshaped by melting them, or the polymers thatcannot be recycled.

Examples

Fluorocarbons Epoxy resins Melamine resins, etc.

Thermoplastics

Those polymers that can be converted or reshaped by melting them, or the polymers that areeasily recyclable.

Examples

Polypropylene Polyethylene PET, etc.

Applications

Production of plastic materials started on an industrial scale in the1940s and 1950s. In the last 15years the global annual production of plastics has doubled, reaching 245 million tons in 2008.

Plastic packaging protects food and goods from getting wasted and/or contaminated andthereby saves resources.

The light weight packaging material (due to high strength-to-weight ratio) saves fuel anddecreases emissions during transportation.

Plastic water supply systems and storage containers/tanks provide clean water. Light plastic materials (replacing metals) in cars and aircraft save fuel and decreases

emissions.

Efficient plastic insulation materials in buildings save energy and provide climateprotection.

Plastic protective clothing and safety equipment (e.g. fire proof materials, helmets, airbags) protects form injury.

Plastic products for medical applications are very important and contribute to improvedheath (e.g. blood pouches, tubings, disposable syringes, prosthesis).


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Solar heaters and solar panels, in parts made of plastics, provide renewable energy.

Figure 1 Life Cycle of Plastic

Environmental Effects

Now a days polymer are used in almost every field of life in different forms like plastics,

rubbers, fibers etc. hence there production is very large to meet the demand of the society. They

have eased the life of a man but there are some disadvantages also, that are related to polymers

directly. Especially there impact on the environment is very hazardous to the eco-system. Forworkers in the plastics industry the main route of exposure to toxic substances is by inhalation

and absorption through the lungs, which according to Lokensgard and Richardson (2004)

accounts for nearly 90 percent of the toxic symptoms observed in the plastics industry. This is

quite expected since many of the hazardous chemicals used in plastic production are volatile

organic compounds (VOCs). The VOCs are mainly emitted during the production phase, but also

during the use and the end of life phase. This causes indoor air pollution which may be harmful

for human health. VOCs also contribute to elevated ground-level ozone levels which may

damage vegetation, can irritate the respiratory system, aggravate asthma and lung diseases, cause

permanent lung damage, and affect the immune system.


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The negative impact of polymers i-e thermosets, thermoplastics and elastomers are described

briefly.

Effect of Thermosets

Thermosets have the adverse effect on the environment as they are highly non-degradabletherefore, they remains in the environment for the unlimited time span. Some of the hazards

caused by thermosetting plastics are:

Liquid resin blends and isocyanates may contain hazardous or regulated components.They should be handled in accordance with manufacturer recommendations found on

product labels, and in MSDS (Material Safety Data Sheet) and product technical

literature. Isocyanates are known skin and respiratory sensitizers, and proper engineering

controls should be in place to prevent exposure to isocyanate liquid and vapor.

Additionally, amines, glycols, and phosphate present in spray polyurethane foams

present unknown risks to the individuals exposed to them. Proper hygiene controls andpersonal protective equipment (PPE), such as gloves, respirators, and protective clothing

and eye wear should be used.

Duroplast cannot be further recycled, and burning it produces toxic fumes, so disposingof the bodies of old Trabants is a problem. However, its components are edible, and

there are stories of pigs, sheep or other farm animals consuming duroplast.

Urea-formaldehyde foam insulation (UFFI) started being used in the 1970s.Homeowners used UFFI as wall cavity filler at the time in order to conserve energy. In

the 1980s, concerns began to develop about the toxic formaldehyde vapor emitted in the

curing process, as well as from the breakdown of old foam. Emission rates of more than

0.1 parts per million (ppm) takes a toxic toll on humans. Consequently, its use wasdiscontinued.

Health effects of Urea-Formaldehyde are put into effect when the elevated level isreached. Urea-formaldehyde releases formaldehyde emissions into the air. This triggers

watery eyes, nose irritations, wheezing and coughing, fatigue, skin rash, severe allergic

reactions, burning sensations in the eyes and throat, nausea, and difficulty in breathing in

some humans (usually 0.1 ppm). Studies have shown that exposure may cause cancer in

humans and animals. Irritation of the mucus membrane (specifically eyes, nose, andthroat) is a common upper respiratory tract symptom to be found in both home and work

environments containing enough UFFI- insulation concentration.

The primary risk associated with epoxy use is often related to the hardener componentand not to the epoxy resin itself. Amine hardeners in particular are generally corrosive,

but may also be classed toxic and/or carcinogenic/ mutagenic. Aromatic amines present a

particular health hazard (most are known or suspected carcinogens), but their use is now

restricted to specific industrial applications, and safer aliphatic or cycloaliphatic amines

are commonly employed.Liquid epoxy resins in their uncured state are mostly classed as


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irritant to the eyes and skin, as well as toxic to aquatic organisms. Solid epoxy resins are

generally safer than liquid epoxy resins, and many are classified non-hazardous

materials. One particular risk associated with epoxy resins is sensitization. The risk has

been shown to be more pronounced in epoxy resins containing low molecular weight

epoxy diluents. Exposure to epoxy resins can, over time, induce an allergic reaction.Epoxy use is a main source of occupational asthma among users of plastics.

Figure 2 Toxic leachates in polymers

Thermoplastics

Several hazardous substances may be released during the life cycle of a plastic product; and

considering the large and growing global consumption of plastic products, and their Omni

presence and persistence in the environment, there is a need for assessing the hazards and risks

of this large material group.


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A very large fraction of plastic waste ends up as litter in the terrestrial and marine environment.

The marine environment is especially exposed and has been most widely studied. Large and

increasing amounts of plastic products, debris, fragments and even micro particles are found in

the open ocean, on the surface, in the Deep Ocean and ocean bed, in coast lines, in sediments,

and in organisms. Effects from entanglement or ingestion of plastic waste, including suffocation

or blocking of digestive tract causing death, have been well documented for birds, turtles, and

marine mammals.The consequences of exposure to micro plastic in filter feeding organisms anddeposit feeders are not yet known. Studies of exposure to micro plastics in amphipods,

lugworms, barnacles, sea cucumbers, and mussels have shown that the organisms ingest the

micro plastics. Marine plastics can also be vectors for transport of sessile alien invasive species

and may cause damage to ecosystems.

The use of polycarbonate containers for the purpose of food storage is controversial. Thebasis of this controversy is their hydrolysis (degradation by water, often referred to as

leaching) occurring at high temperature, releases bisphenol A. Bisphenol A appeared to

be released from polycarbonate animal cages into water at room temperature and it may

have been responsible for enlargement of the reproductive organs of female mice

One of the main problems of polyethylene is that without special treatment it is notreadily biodegradable, and thus accumulates. In 2009 it was discovered by a resident of

Hawaii upon returning from a ship race that degraded plastics are a major cause for

marine life destruction, being mixed in with plankton, comparable in size and weight but

in much larger numbers. During the 1980s and 1990s it was shown that many endangered

marine species including birds that live in the marine environment are at extra hazard,

with thousands of cases of suffocation from swallowing plastic bags or plastic content.

Polystyrene foams are produced using blowing agents that form bubbles and expand thefoam. In expanded polystyrene, these are usually hydrocarbons such as pentane, which

may pose a flammability hazard in manufacturing or storage of newly manufactured

material, but have relatively mild environmental impact. Extruded polystyrene is usually

made with hydro fluorocarbons (HFC-134a), which have global warming potentials of

approximately 10001300 times that of carbon dioxide.

Polystyrene foam is a major component of plastic debris in the ocean, where it becomeshazardous to marine life and "could lead to the transfer of toxic chemicals to the food

chain". Animals do not recognize this artificial material and may even mistake it for food.

Polystyrene foam blows in the wind and floats on water, and is abundant in the outdoor

environment. It can be lethal to any bird or sea creature that swallows significant

quantities


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Of all plastics, PVC has probably received the most legislative and research attention inthe Health and Safety area due to the NGO's environmental attack in the 1990s. It hasbeen claimed that some plasticizers leach out of PVC products. However, it has been

difficult to prove that plasticizers readily migrate and leach into the environment from

flexible vinyl articles because they are physically and tightly bound into the plastic as a

result of the heating process used to make PVC particles. The Japanese car companiesToyota, Nissan, and

Honda have eliminated

PVC in their car

interiors starting in

2007.

In 2004 a joint Swedish-Danish research team

found a statistical

association betweenallergies in children and

indoor air levels of

DEHP and BBzP (butyl

benzyl phthalate), which

is used in vinyl flooring.

While extremely usefulas a food packaging

agent, the major disadvantage of Saran is that it will undergo thermally induced

dehydrochlorination at temperatures very near to processing temperatures. This

degradation easily propagates, leaving polyene sequences long enough to absorb visible

light, and change the color of the material from colorless to an undesirable transparent

brown (unacceptable for one of Saran's chief applications: food packaging). Therefore,

there is a significant amount of product loss in the manufacturing process, which

increases production and consumer costs.

Elastomers

The pneumatic tire is one of the most common items in the contemporary world. More than 800

million new tires are produced annually, in every region of the world, in a dizzying array of sizes

and types, to serve an equally dazzling multiplicity of users on vehicles of every kind anddescription. Increasingly, tires that reach the end of their serviceable lifetime are processed for

beneficial reuse in novel applications. These include soil and surface amendments at athletic

fields, playground and garden mulch, and bound surfaces at playgrounds and athletic facilities.

These modern artificial surfaces reduce the likelihood of personal injury, provide uniform

recreational playing surfaces, promote energy conservation, and eliminate pesticide and fertilizer


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usage, and support waste recycling. Tires are manufactured with a variety of materials and

additives to ensure optimum product safety, reliability and performance. Some tire ingredients

are considered to be human health hazards at exposure levels several orders of magnitude greater

than possible from contact with finished consumer products. Accordingly, athletes, parents and

other stakeholders have expressed questions and concerns about the potential for adverse human

health or ecological effects from the use of recycled tires in sport surface or playground

materials.

Specific concerns are that particles of ground rubber may be inhaled or ingested; thatdermal exposure may result in natural rubber allergy; or that VOCs and other chemicals

such as PAHs may be emitted from ground rubber, resulting in negative impacts on

human health or the environment.

Even while reactive chemicals may not be available for release from end-product tires,the identification of chemicals used in tire manufacturing as mutagens, carcinogens, or

reproductive toxicants has resulted in a significant amount of attention on safety from the

use of recycled tires in applications such as playground surfaces and artificial turf athletic

fields, particularly in light of the fact that one of the exposure populations is children.

Oral ingestion of ground rubber, either intentional or incidental, is unlikely to represent amajor exposure pathway. However, consideration of this pathway is necessary, especially

in the case of children who may consume ground rubber or pieces of poured rubber at

playgrounds.

While most studies evaluating the leaching of chemical constituents into water sourceshave focused on impact on ecological systems, a few have addressed the issue of whether

leaching of recycled tire material may impact drinking water, and thus present a human

health risk.


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References

www.wikipedia.com http://www.mst.dk/Publikationer/Publications/2010/12/978-87-92708-75-5.htm http://chm.pops.int/Convention/The%20POPs/tabid/673/language/en-US/Default.aspx http://www.vinyl2010.org/about-us/our-history.html http://www.naturvardsverket.se/Documents/publikationer/620-5744-8.pdf Modern Plastic Mid-October Encyclopedia Issue, Introduction to TPEs, page:109-110
http://www.wikipedia.com/http://www.mst.dk/Publikationer/Publications/2010/12/978-87-92708-75-5.htmhttp://chm.pops.int/Convention/The%20POPs/tabid/673/language/en-US/Default.aspxhttp://www.vinyl2010.org/about-us/our-history.htmlhttp://www.naturvardsverket.se/Documents/publikationer/620-5744-8.pdfhttp://www.naturvardsverket.se/Documents/publikationer/620-5744-8.pdfhttp://www.vinyl2010.org/about-us/our-history.htmlhttp://chm.pops.int/Convention/The%20POPs/tabid/673/language/en-US/Default.aspxhttp://www.mst.dk/Publikationer/Publications/2010/12/978-87-92708-75-5.htmhttp://www.wikipedia.com/

Hazards of Polymers

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