'Chemicals' and Health

There’s a common myth that all ‘chemicals’ are bad. In reality, every substance is a chemical or combination of chemicals. Each day we interact with myriad chemicals. Some are good for us, like H20, better known as water, which makes up about 65% of our body. We don’t like ozone at ground level as it is bad for our respiratory systems, but we love it when it floats around the atmosphere 10 to 50 km above the earth’s surface where it acts as a layer of sunscreen for the planet.

What we’re really interested in are those chemicals that pose a health threat to people. The real health risk of any given chemical relates to both how hazardous it is by nature and how much of it a person is exposed to. It also depends on the particular sensitivities of each unique person.

In discussing the health impacts of potentially harmful chemicals, it helps to have a broad understanding of how different substances can affect our bodies. This information is adapted from Tanya Ha’s book The Australian Green Consumer Guide.

  • Toxicity – Toxicity is the degree to which a given amount of a substance is poisonous, causing harm to the body’s tissues. Toxins, in contrast to allergens, are poisonous to some degree to all people.
  • Carcinogenicity – Some substances can cause or contribute to the development of cancer.
  • Oestrogenicity – Some substances indirectly affect health by behaving in a similar way to hormones, in particular the female hormone oestrogen. Such substances are called ‘endocrine disruptors’ because there is evidence to suggest that they can influence and damage the endocrine systems of animals and humans that ingest them. They also have a tendency to bioaccummulate in the body’s tissues. Common endocrine disruptors include some pesticides, heavy metals, organochlorines and some plasticisers and surfactants.