Science

Safety and sustainability

There are safety issues that are associated with the many industrial chemicals that exist. As well as safety, environmental impacts must be considered. A life cycle assessment (LCA) can be used to assess the impact.

Health and the environment - Ideas about science

A large number of industrial chemicals exist and have a range of uses. These uses include consumer products. The safety of these chemicals must be checked to identify any risks they may pose to human health and the environment.

Some chemicals used in synthetic materials are harmful in large doses but not in the concentrations used in the products. Other synthetic materials are harmful even in these small amounts.

Persistent organic pollutants (POPs) are a class of chemicals that take a long time to break down and can harm people and wildlife. Because they take so long to break down they can be carried over large distances in air and water. POPs accumulate in the fatty tissues of animals, including humans. Exposure to POPs can lead to illness and in severe cases death.

Many countries have outlawed these chemicals, for example the UK has banned many of these chemicals already.

PVC and plasticisers

Polyvinyl chloride (PVC) is a widely used plastic containing carbon, hydrogen and chlorine. It is produced by the process of polymerisation. Molecules of vinyl chloride monomers combine to make long chain molecules of polyvinyl chloride.

This synthetic polymer is relatively cheap and easy to mould. There are different types of PVC that are manufactured, serving a range of uses from underground pipes carrying water, gas and sewage to thinner films used in packaging.

PVC pencilcase. Credit: Andy Crawford

PVC is used to make a wide range of products such as this pencil case.

Polymer with vinyl monomers

Vinyl chloride monomers make up these polymer chains. Carbon atoms are shown in black, hydrogen in white and chlorine in green

Plasticisers

Plasticisers are used to make a material like PVC softer and more flexible. They are small molecules that can dissolve into liquids that come into contact with them. The most common plasticisers used for PVC are phthalates.

Child with plastic toy. Credit: Elie Bernager

When plastic toys are chewed by a child the plasticiser may be dissolved by the saliva of the child and possibly ingested.

Some argue that phthalates should be banned due to evidence linking them with health problems such as cancer. Others say that products containing phthalates have been used for over half a century and no known cases of harm has been documented due to the use of phthalates.

Some plasticisers have been banned by regulators in Europe and the USA.

Making life cycle assessments

A life cycle assessment, or LCA, can be used to assess the environmental impact of the manufacture and use of different materials and products.

Making a life cycle assessment

The articles that we use have three main life stages: manufacture, use and disposal. A life cycle assessment, or LCA, is a study of the stages in the life of a manufactured product.

Key features

Polymers have recycling symbols like this one for PVC to show what they are

Polymers have recycling symbols like this one for PVC to show what they are

The key features of a life cycle assessment include the following factors:

  • the main requirements for energy input
  • the environmental impact and sustainability of making the materials from natural resources
  • the environmental impact of making the product from the material
  • the environmental impact of using the product
  • the environmental impact of disposing of the product by incineration, landfill or recycling.

Materials and products

Different materials

It is possible to make a product from different materials, for example. A window frame, for example can be made from wood or uPVC. The life cycle assessment for a product will depend on the material that it is made from.

Different products

It is possible to use the same material to make different products. Polythene can be used to make food wrap (cling film) or a bucket, for example. The life cycle assessment of different products will be different, even though they are made from the same material.

A life cycle assessment can be used to compare and evaluate the impact of:

  • the use of different materials for the same job
  • the use of the same material for different jobs.

LCA outcomes- Higher tier

It is possible to make a life cycle assessment of a material. The outcome of this life cycle assessment will depend on:

  • a consideration of the factors involved in the production of the material
  • a consideration of the factors that involve each of the products that are made from this material.

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