- Polychlorinated dibenzo-p-dioxins (PCDDs, dioxins)
- Polychlorinated dibenzofurans (PCDFs, furans)
- Polychlorinated biphenols (PCBs).
Dioxins, furans and PCBs are formed by activities such as:
- combustion of wastes including medical and hazardous wastes
- exhaust emissions from vehicles
- metallurgical industries including metal smelting, refining and recycling
- controlled burn-offs
- industrial and domestic coal and wood combustion
- uncontrolled and accidental fires including landfill fires
Dioxins and furans
Dioxins and furans can adversely affect human and animal health in a number of ways, including by:
- affecting the immune and reproductive systems
- causing birth defects
- affecting neurobehavioural development
- causing cancer
- causing liver damage.
The most noted health effect in people exposed to large amounts of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) is an acne-like skin condition known as chloracne.
The International Agency for Research on Cancer has determined that 2,3,7,8-TCDD is a human carcinogen (ie, it can cause cancer in humans).
High levels of PCBs cause:
- liver problems
- skin rashes
- eye irritation.
Animal studies have shown developmental effects and there are reports of reduced short-term memory in children of mothers exposed to PCBs through what their mothers' ate.
We do not know if PCBs cause cancer in people.
The United States Environmental Protection Agency has classified PCBs as probable human carcinogens (Group B2) see the agency's Air toxics website.
- humans particularly foetuses and young children
- some animals.
New Zealand does not currently have inhalation guideline values for dioxins and furans. The Ministry has developed seven national environmental standards that ban activities that discharge significant quantities of dioxins, furans and other toxins into the air.
The Ministry has some information on the levels of dioxins, furans and PCBs in the air and other parts of the environment. Generally, concentrations of these pollutants are low when compared to usual concentrations found in other countries. Dioxin levels in air have been found to be elevated during colder months when more wood is burnt for domestic heating.