Hazardous chemicals are substances that are dangerous to people, wildlife and the environment at any stage of their lifecycle, from production to use to disposal.
They are defined by several characteristics:
They are persistent:
Hazardous chemicals stay in the environment for long periods of time, and do not biodegrade or break down easily.
Because hazardous chemicals are slow to break down, they can remain in the soil, water or ice for many years after they have been banned.
DDT, one of the most notorious toxic pesticides, is still found in the environment today, even though it was banned in many nations in the 70s and 80s.
They are bioaccumulative:
Hazardous chemicals can build up in the bodies of organisms over time, and they can be spread via the food chain.
For example, a factory may discharge perfluorinated compounds (PFCs), an extremely persistent pollutant, into the river. The PFCs may then be absorbed by small fish and other aquatic organisms. As they are eaten by bigger animals, the PFCs are passed on as well, moving up to the next level of the food chain. As the PFCs travel up the food chain, they become more concentrated – thus, the largest quantity of chemicals are usually found in top-level predators such as polar bears or people.
Numerous studies have found PFCs throughout the food chain, from aquatic invertebrates, fish and amphibians to large mammals such as whales and polar bears. Polar bears especially face many health threats from hazardous chemicals, not just PFCs.
They are toxic to organisms:
Hazardous chemicals have a range of toxic effects to animals and people. Depending on the type of chemical, they can cause cancer, damage the nervous system, disrupt the reproductive system or alter the function of hormones, just to name a few negative effects.
Endocrine disrupting chemicals
A special group of hazardous chemicals is called endocrine disrupting chemicals (EDCs). Also known as hormone disruptors, they are particularly harmful due to their ability to disrupt the proper function of the body’s hormones. Hormones act as the body’s chemical messengers, passing along critical information. The system of hormones is called the endocrine system, and it is crucial to the body’s healthy functioning.
Exposure to EDCs is the most dangerous for developing fetuses. The chemicals can impact – sometimes severely – the development of the brain, nervous system and reproductive system. EDC exposure in adults has also been linked to various cancers, decreased sperm count, thyroid disease, lowered fertility and more.
EDCs encompass many different kinds of hazardous chemicals, such as drugs, pesticides, industrial pollutants and persistent organic pollutants. Some examples include DDT, phthalates (plasticizers), alkylphenols, bisphenol A and some types of brominated fire retardants.