Persistent organic pollutants

What is toxaphene?

Toxaphene does not occur naturally in the environment. Toxaphene is an amber, waxy, turpentine-scented pesticide containing over 670 chemicals. It is a solid that does not burn but is easily vaporized. It does not dissolve easily in water.

Toxaphene was first used in North America in 1949. Toxaphene was one of the most heavily applied insecticides in the United States, though it had only limited use in Canada. It was used primarily to control insect-pests on cotton and other crops. It was also used to control pests on livestock and to kill unwanted fish species in lakes.

When toxaphene use was at its peak in the mid-'70s, people became concerned about its toxicity, the way it accumulated in aquatic organisms, and the way it stayed in the environment for many years. Toxaphene's effect on human and animal health led to a ban on its use in Canada and the United States in 1982.

Toxaphene is still used in some parts of the world, mostly to control insects on banana and pineapple crops.

How does toxaphene enter the environment?

Toxaphene is found in many parts of the world where it was never used because it evaporates into the air and is carried on air currents over long distances. Toxaphene does not dissolve well in water, so it is most likely to be found in the soil or in sediments at the bottom of lakes or streams. It is also found in the tissues of aquatic organisms.

Once toxaphene enters the environment it remains there for a long time. Toxaphene has a half-life of up to 12 years in soil. Studies have shown that people in the Canadian Arctic who have a traditional diet of fish and marine animals consume 10 times the accepted tolerable daily intake of toxaphene.

It is difficult and expensive to measure toxaphene in the environment, and the extent of toxaphene contamination of the North has only recently been understood.

How toxic is Toxaphene?

Toxaphene is no longer used in North America so risk of high-level exposure is low. Long-term exposure to low levels of toxaphene has the potential to cause liver and kidney degeneration, affect the central nervous system and suppress the immune system.

There is currently little information available on the developmental and reproductive effects of toxaphene on humans. Acute poisoning from the prolonged ingestion or inhalation of high levels of toxaphene causes damage to the lungs, the nervous system, and the liver and kidneys in humans.

Toxaphene builds up in human fat, so people most at risk are those with a diet that includes large quantities of the fatty tissues of fish, shellfish or marine mammals.

In the Yukon, toxaphene levels in trout from Kusawa Lake and Lake Laberge are well below the Health Canada guidelines.

What are the effects of toxaphene on our environment?

Toxaphene is very persistent, remaining in the soil for many years. It is not broken down by microbial organisms. It may gradually evaporate in the air, where it is slowly broken down by sunlight.

Toxaphene has been found in high concentrations in shellfish, algae, fish and marine mammals. In the Arctic, blubber from beluga whales has been found to contain unhealthy levels of toxaphene.

Levels of toxaphene may be higher in predatory mammals that eat mainly fish because toxaphene accumulates in the fish's fatty tissues.

The major toxic effect of toxaphene on animals is on the nervous system. Fish are extremely sensitive and become hyperactive, suffering muscular spasms and losing their equilibrium.

In the early 1990s, high concentrations of toxaphene were found in the tissues of fish in some Yukon lakes. Predatory species such as lake trout and burbot were particularly affected. Subsequent studies have shown that toxaphene levels in these fish species have decreased and are below Health Canada guidelines.

In Lake Laberge this decrease is believed to be associated with a change in the diet of the predatory fish as the lake recovered from commercial fishing.

• toxaphene is a synthetic organic compound made from over 670 chemicals. It is not found naturally in our environment
• the Yukon Contaminants Committee has been investigating toxaphene levels in the Arctic and sub-Arctic environment for many years
• toxaphene is carried to the North from other parts of the world in air currents
• toxaphene remains in soil and lake sediment for many years
• toxaphene is persistent, accumulates in the food chain and is toxic
• the greatest concentration of toxaphene in the northern environment is found in the tissues of marine mammals such as whales and seals
• toxaphene has negative health effects in humans, including suppression of the immune system, negative effects on the central nervous system and degeneration of the kidneys and liver
• toxaphene levels are declining in Yukon freshwater fish species and are below Health Canada guidelines

What are Polybrominated Diphenyl Ethers?

Polybrominated Diphenyl Ethers (PBDEs) do not occur naturally. They are a humanmade chemical used in flame-retardants. PBDEs are added to products like electronic devices, couches, foam padding in vehicles, and clothes. As flame-retardants, they help reduce the risk of death by fire by up to 45 percent.

PBDEs are now found throughout the environment in sewage, animals, fish, humans and food. PBDEs are fat-soluble and build up in the fatty tissues of both animals and humans from before birth until death. PBDEs cannot be dissolved in water, and tend to accumulate in sediments.

How do PBDEs enter the environment?

There are several theories about how PBDEs get into the environment. The primary release point is from manufacturing, when PBDEs are added or mixed into products. They are also released from landfills when sunlight and water break down discarded products containing PBDEs. Insects have been seen eating this material, which then travels up the food chain. High concentrations of PBDE and related compounds have been found everywhere, including in fish-eating birds and mammals, human blood and breast milk. This suggests that PBDEs accumulate in the environment and food chains by concentrating in living tissues and increase at each link in a food chain.

PBDEs are also considered airborne pollutants, which can be released when household garbage is burned. Current tests show that levels in the Yukon at Little Fox Lake are low, similar to other parts of the Western Arctic and are well below Health Canada guidelines.

PBDEs are not manufactured in Canada but are imported in finished products. Canada is working with industry to minimize the impact of PBDEs on the environment. The substances that are likely of greatest concern are being phased out of use in Canada.

How toxic are PBDEs?

PBDEs are considered toxic. Early testing done on PBDEs suggest that they are as toxic as other POPs, which have been banned since the mid-1960s. Levels of PBDEs are slowly increasing. Levels of all organic POPs, including PBDEs, are monitored in lake trout from Kusawa and Laberge lakes and are below Health Canada guidelines.

Although the acute toxicity of PBDE is low, there is concern for its long-term effects on the endocrine (glandular) system. The chemical structure of PBDE resembles a thyroid hormone and studies indicate that PBDEs could interfere with the metabolism and distribution of thyroid hormones in the body. The effects may include reduced learning capacity and hyperactive behaviour. This effect was observed when baby mice came into contact with very low doses of PBDEs.

Although human breast milk contains PBDEs, scientists have determined that the benefits of breastfeeding outweigh the risks.

The most common exposure to PBDEs is through indoor air and not through food. PBDEs can be emitted from upholstery, carpets, fabrics, etc.

Facts about PBDEs

• PBDEs are human-made chemicals used in flame-retardants. They do not occur naturally
• burning household goods releases PBDEs into the atmosphere
• PBDEs accumulate in the food chain, biomagnify and are persistent
• PBDEs have been found in Arctic mammals
• despite a European ban on PBDEs, in 1998 there were 40 times more PBDEs in the environment of Sweden than there had been in 1972
• North American women have PBDE levels 40 times greater than concentrations found in Sweden
• Canada banned the use of the most toxic PBDE compound (penta-PBDE) in 2005
• scientists warn environmental contamination by PBDEs is doubling every 5 years
• PBDEs are monitored in the Yukon and are below Health Canada guidelines

What are polychlorinated biphenyls?

Polychlorinated biphenyls (PCBs) are a family of synthetic chlorinated hydrocarbon compounds and were used for everything from paint to lubricants to electrical transformer fluid, especially during the post–World War II era. PCBs were excellent electrical insulators and fire-fighting compounds.

There are more than 200 types of PCBs. The less chlorinated compounds are clear and oily. A concentrated PCB product is yellowish brown, resin-like and smells like garlic.

Use of PCBs stopped when the health and environmental effects of the chemicals became well known in the late 1960s. It was banned in most countries, including Canada, in 1970, but PCBs are common in old landfills, sediments and wildlife.

PCBs are one of the most highly regulated organic compounds in the world . In Canada it is regulated through the Canadian Environmental Protection Act.

How do PCBs enter the environment?

PCBs enter the environment from point sources such as leaks and spills from PCB devices. PCBs also enter the environment through global transport. The Arctic haze visible throughout the circumpolar world contains PCBs along with other POPs.

International agreements to control emissions are recognized as the only long-term solution to the problem of contaminants in the Arctic. International agreements concluded in 1998 and 2001 pledge the reduction of key heavy metal and POP emissions into the environment.

The post–World War II era of "wonder chemicals" produced a large variety of PCBs. About 75 percent of the PCBs made in North America were used as cooling and insulating fluid for electrical devices. Other products included:

• fluorescent light ballasts
• hydraulic oil
• fire extinguisher fluid
• dust suppressants
• adhesive tape
• paint

Current Canadian requirements prevent the use of PCBs in all of these products.

Over one million tonnes of PCBs were produced worldwide. A small amount has been safely destroyed, as was done at the DEW Line stations across the North in the 1990s and some has been safely stored. However a great deal remains in use or is contained in old equipment in landfills.

A small amount of PCB was brought to the Yukon after the construction of the Alaska Highway. The last significant PCB remediation project in the Yukon was in 1994, when 3,840 litres of liquid PCB and 183,200 kilograms of PCB-contaminated soil were shipped to the Swan Hills facility for disposal.

How are people exposed to PCBs?

PCBs do not dissolve easily in water, and they stick to the surface of tiny suspended particles in water, air and soil. From there, PCBs are eaten by all sorts of animals, then lodge in fatty tissue.

In the North, the Eastern Arctic has been most affected, with levels 5 times lower than those found in Greenland but up to 8 times higher than those in the rest of Canada. Nearly half of the mothers in the Eastern Arctic have PCB levels of concern in their blood due to higher concentrations found in their traditional diet. Research conducted on children born to women who ate a lot of contaminated fish suggests that PCBs can have serious prenatal effects on intellectual function.

In the Yukon, scientists have detected PCBs in fish and in caribou but levels are declining. Between 1993 and 2008, PCB levels in Yukon lake trout declined by 80 percent. PCB levels in the Yukon are below health-warning concentrations, and have been generally decreasing over time.

Facts about PCBs

• PCBs are synthetic organic compounds. They are not found naturally
• PCBs are persistent, accumulate in the food chain and are toxic
• PCBs accumulate in the fatty tissue of lower organisms and become more concentrated as they move up the food chain
• the highest concentrations of PCBs in living organisms are in the fat of long-lived animals and in humans
• PCBs have negative health effects. They can cause cancer in animals, and have other effects on the immune, reproduction, and nervous and endocrine (glandular) systems of animals
• the North has few point sources of PCBs but receives PCBs as airborne global contaminants
• country food is not highly contaminated with PCBs
• PCBs are in decline in fish and most mammals and, in the Yukon, are below Health Canada guidelines

What is Perfluorooctane sulfonate?

Perfluorooctane sulfonate (PFOS) is an organic compound produced synthetically in a process known as electrochemical fluorination. PFOS is used primarily as an ingredient of household waterproofing compounds like sprays for repelling water and keeping clothes, furniture and carpets from staining.

PFOS is used in coatings for candy wrappers and food containers because it is formulated to repel oil, grease and water. ScotchgardTM is probably the best-known product to have contained PFOS, but has removed PFOS from its formulation. PFOS can also be found in paper plates, shower curtains, linen, footwear and upholstery.

Manufacturing and use of PFOS has been widespread since the 1940s. Concerns over PFOS's toxic effects on human health and the environment began in the 1970s, but only recent analytical techniques have been able to clearly identify its toxic characteristics.

The United States is the major manufacturer of PFOS, although production and use of PFOS is being phased out because of concerns over its environmental toxicity.

How does PFOS enter the environment?

It is now known that PFOS is widely distributed on a global scale. PFOS is found in animal tissues around the world, even in remote areas.

Although globally widespread, PFOS concentrations are greater in industrialized regions. PFOS is believed to be transported by winds to remote areas of the world such as the Arctic and Antarctic, far from where it was manufactured or used.

How toxic is PFOS?

There is still very limited information on the effects of PFOS on human health.

PFOS does not accumulate in fats. Instead, this organic compound binds to blood proteins and accumulates in the liver and gallbladder.

PFOS is readily absorbed orally by the body, is very slowly eliminated, and is not well metabolized. Due to good oral absorption, poor elimination and extensive protein binding, the more PFOS a human being consumes, the more will build up in that person's liver and blood.

The greatest concern when it comes to PFOS is the length of time it stays in the body, its persistence. Toxicological studies show that liver enlargement is one way the body responds to high doses of PFOS.

It is not known if PFOS affects post-natal development, although there is evidence that PFOS crosses the placenta and occurs in milk.

Government of Canada scientists found that current levels of exposure for PFOS are below levels that would harm human health, but that some wildlife such as polar bears and fish-eating bird species could be at or near levels that could cause harmful effects.

In the Yukon, PFOS levels in Kusawa Lake and Lake Laberge are monitored by the Northern Contaminants Program and levels are well below the Health Canada guidelines. A study ending in 2008 demonstrated that lake trout livers have very low levels of PFOS.

What are the effects of PFOS on our environment?

The release of PFOS into the environment can occur during its manufacture, during its commercial application and after the disposal of the end product. During domestic application with aerosol containers, as much as 34 percent of the PFOS in a product is lost to the atmosphere. Most waste products containing PFOS are either incinerated or disposed in landfills. Smaller amounts are released into waste water and into the air.

Recent studies have found concentrations of PFOS in polar bears in northern Alaska, seals in the Baltic Sea and the Arctic Ocean, dolphins in Florida and sea otters in California. Measurable quantities of PFOS have been detected in both freshwater and saltwater fish, including Chinook salmon, lake whitefish, brown trout, carp and tuna. PFOS has also been found in a number of fish-eating birds such as loons, cormorants, ospreys, eagles, pelicans, herons, gannets and gulls. Albatross in the mid-Pacific Ocean have also been affected.

Unlike some of the persistent organochlorines, such as DDT and PCBs, PFOS contamination appears to be lower in remote regions of the world. PFOS concentrations are greater in developed and industrialized locations. Although there is a surprisingly widespread distribution of PFOS in mammals, birds and fish, and PFOS has shown to be persistent and bioaccumulative in various food chains, the amounts found in wildlife are small relative to those shown to cause damage to animals in laboratory tests.

The biggest concern about PFOS in the environment is its extreme persistence. PFOS does not break down in the environment. In 2009, Canada added PFOS to a list of chemicals in legislation that must be eliminated from use.

Facts about PFOS

• PFOS is not found naturally in our environment. It is a synthetic compound used primarily as a water repellent
• it was recently discovered that PFOS is a widespread global contaminant
• Canada has placed PFOS and its salts on the Virtual Elimination List under the Canadian Environmental Protection Act
• PFOS accumulates in the tissues of humans and animals, primarily in the blood, liver and gallbladder
• PFOS does not accumulate in fats
• the human body is slow to rid itself of PFOS
• the effects of PFOS on human health are largely unknown
• PFOS is one of the most prominent toxic chemicals in the Arctic
• PFOS levels are well below Health Canada guidelines in the Yukon