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chemicals and toxicity

what you know can help you

When it comes to chemicals and toxic substances, what we know can help us reduce exposure. Understanding what chemicals are toxic, where they are commonly found, and how to reduce exposure can reduce our risks of harmful health effects.

what is a toxic chemical?

Toxicity of a chemical refers to its ability to damage an organ system, disrupt a biochemical process, or disturb an enzyme system. Basically, a toxic chemical can be poisonous or cause adverse health effects.

For every chemical, there are conditions in which it can be harmless and, conversely, conditions in which it can be harmful. There is a complex relationship between a chemical and the health effects it produces. An important factor to consider is the dose-time relationship, which distinguishes between acute toxicity and chronic toxicity. 

acute toxicity

Acute toxicity of a chemical refers to its ability to inflict systemic health damage as a result of a one-time exposure to a large amount of a chemical. Acute toxic exposure can cause severe injury or death as a result of short-term, high-level exposure. In most cases, exposure is accidental, sudden and results in an emergency situation.

Examples of toxics with acute health impacts: hydrogen cyanide, hydrogen sulfide, nitrogen dioxide, organophosphate pesticides, and arsenic.

chronic toxicity

Chronic toxicity of a chemical refers to its ability to inflict systemic damage as a result of repeated exposure, over a prolonged period of time, even with relatively low levels of the chemical. 

Examples of toxics with chronic health impacts: lead, chlorinated solvents, glyphosate pesticides, mercury, and many more.

toxic effects

The toxic effects from chemical exposure depend on a number of variables: the amount of a substance one is exposed to, how often and for how long during a specific time, the route of exposure, age, general health and nutrition, gender, reproductive status, lifestyle factors, chemical sensitization, genetic predispositions, and multiple exposures. 

Basically, we each have our own healing capacities and body burdens to consider. Once we reach a certain level of body burden due to exposures, we start to notice more adverse health effects.

reproductive toxics

Reproductive toxicants are chemical toxics that can produce health abnormalities, disease, and disabilities in developing embryos. Some chemicals used in therapeutic drugs are capable of causing these adverse effects. Some chemicals, including heavy metals, aromatic solvents, ionizing radiation, and chemicals found in cigarettes and alcohol are known to affect human reproduction. 

Some known reproductive toxics include: acrylonitrile, carbon disulfide, benzene, chloroform, benzo(a)pyrene, sodium azide, and cadmium nitrate. 

Need the facts?

"Environmental Health, Safety, and Risk Management: Toxic Chemicals" LINK

We highly recommend Green Science Policy Institute's Six Classes Approach to Reducing Chemical Harm LINK

For a list of toxics profiles, check out Eco-USA's About Toxics Profiles  LINK

"Environmental Toxicants: Types, Sources & Effects" LINK

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types of toxicants

A Toxicant is a Toxic Substance Released in the Environment

As mentioned before, there's a wide variety of toxicants in the environment. To better understand them, we can put them into specific categories that are based on the types of problems they cause.

Types of Toxicants

Carcinogens are probably the best-known toxicant because these are cancer-causing chemicals. Cigarette smoke falls into this category as it contains over 4,000 chemicals, many of which cause cancer.

Mutagens are mutation-causing chemicals. When organisms are exposed to a mutagen, it literally mutates their DNA, leading to cancer and other disorders. X-rays are well known mutagens.

Teratogens are chemicals that cause harm to unborn babies. The name of this toxicant comes from the Greek word teras, which means monster.

These chemicals cause birth defects during development in the womb. Thalidomide was used in the 1950s as a sleeping pill and to prevent nausea during pregnancy, but turned out to be a very harmful teratogen. Even a single dose is powerful enough to cause severe birth defects in children.

Allergens are chemicals that stimulate overactivity in the immune system. When you are exposed to allergens, your body goes into overdrive, triggering an immune response to try and get rid of the allergen. This is why pollen and dust cause symptoms that are similar to being sick.

Neurotoxins are chemicals that attack the nervous system. These include heavy metals, like lead and mercury, as well as pesticides and chemical weapons. Neurotoxins can lead to symptoms like slurred speech, loss of muscle control and even death.

Endocrine disrupters are chemicals that disrupt the endocrine system in organisms and most often come from prescription drugs and chemicals in plastics. The endocrine system is also known as the hormone system, and this part of your body is what regulates growth, development, sexual maturity, brain function and even appetite.

Toxicants that disrupt hormone functioning can lead to some serious problems because they so closely resemble real hormones in your body. Reptiles and amphibians are especially sensitive to endocrine disrupters and exposure often leads to feminization of male animals. This may seem like a lot to remember! But if you look closely, you'll see that the name of the toxicant describes the effect it has on organisms, which helps us understand these toxicants better.