Food Contamination and Safety Concepts Persistent Organic Pollutants

Food Contamination and Safety • Concepts • Persistent Organic Pollutants (POPs) – E. g. PCBs • Heavy Metals – E. g. Mercury

Food Contamination and Safety • Northern plants and animals are exposed to contaminants that accumulate in the North • Pollutants move from soil and water into plants, and from there into animals • The carnivore diet of humans in the Arctic involves the consumption of species high up in the food chain This results in a higher chance of poisoning • Feeding on caribou vs. marine mammals exposes humans to different levels of contaminants

Concepts Bioaccumulation • The process by which a contaminant accumulates in the tissues of an individual organism • E. g. certain chemicals in food eaten by a fish tend to accumulate in its liver and other tissues – the chemicals are taken in faster than the individual can get rid of them – PCBs are stored in fat – Cadmium is stored in the kidneys – Mercury is stored in the liver

Bioaccumulation

Concepts Biomagnification • Increase in concentration of certain stable chemicals (for example, heavy metals or fatsoluble pesticides) in successively higher trophic levels of a food chain or web. • E. g. metals such as mercury, persistent organic pollutants (POPs) such as PCBs, pesticides, dioxins • Note: Not all contaminants biomagnify

Biomagnification

An extra link, on top of an already long food chain

Contamination: Persistent Organic Pollutants (POPs) • Also called organochlorines • An organic compound containing chlorine • E. g. polychlorinated biphenyls (PCBs); common pesticides, such as DDT or Dioxin

Persistent Organic Pollutants (POPs) • Highly toxic chemicals • Estimated that 400 million tons are produced annually worldwide • The “dirty dozen” aldrin, chlordane, DDT, dieldrin, dioxins, furans, endrin, HCB, heptachlor, mirex, PCBs, toxaphene • Stored in fat and are persistent

Organochlorines

Example: Polychlorinated Biphenyls (PCBs) • No longer produced in North America, but are still produced in some developing countries • Were commonly used as lubricants in hydraulic fluid, transmission oil, and in electrical transformers • Considered a POP they stay in the environment for a long time and travel long distances

Polychlorinated Biphenyls (PCBs) • PCBs biomagnify • At low level in food can affect the reproductive system and thyroid, may damage the immune and nervous system • Prenatal infants exposed to PCBs tend to have a higher incidence of upper respiratory-tract infections • Suspected to cause liver, skin, and intestinal cancers

Levels of POPs in blood plasma

Average intake of POPs/day

Contamination: Heavy Metals • Minerals that are naturally present in rocks and soils in all parts of the world, including the bed rock and unconsolidated material of the Canadian Arctic • E. g. mercury, cadmium, lead • Cadmium and mercury are released as a byproduct of mining and smelting primary longrange transport is through the atmosphere • Significant quantities of mercury are also released as a result of the erosive and chemical actions that take place in reservoirs built to store water for large hydro-electric projects • Metal levels are highest in people who eat large amounts of organ meat

Example: Mercury • Mercury is a natural element that occurs in terrestrial and aquatic ecosystems in the Arctic • Atmospherically deposited mercury is emitted from sources such as coal-fired electric utilities and waste incinerators in the south • Global levels of atmospheric mercury are increasing each year

Mercury • Major source of mercury is through meat, in the form of methyl mercury • Highest in people who eat a lot of marine food • Methyl mercury is easily taken up through the intestinal wall • Major health concern is damage to the brain and nervous system, may also affect the immune system • Methyl mercury easily passes through the placenta and can affect the fetus may cause neurological damage

Methyl Mercury

Mercury in Maternal Blood Region West. NWT N-central NWT Nunavik (N. Québec) NW Greenland N Sweden N Norway Iceland Nikel, Russia Micro-grams mercury/liter whole blood 1. 7 3. 5 13. 7 19. 8 1. 6 2. 3 2. 9 2. 3

Time trend of mercury concentration in blood

Case Study: James Bay Project • The construction of a series of hydroelectric power stations on the La Grande River in northwestern Québec • One of the largest hydroelectric systems in the world • Installed generating capacity of 16, 000 megawatts 3 x more power than the power station at Niagara Falls!

James Bay Project • 1971: plans unveiled for the construction of several large hydroelectric power stations on the rivers flowing into James Bay • Environmental assessments were not required under Québec law at the time • Strong opposition to the project by the Crees of James Bay, the Inuit to the north, and several environmental groups – They believed the government was violating treaties and committing unlawful expropriation and destruction of traditional hunting and trapping lands – The Cree and Inuit were not informed of the project until after the construction of access roads had begun

James Bay Project • 1975: the governments of Canada and Québec signed the James Bay and Northern Québec Agreement with the Cree and Inuit – Granted exclusive hunting and fishing rights to ~170, 000 km 2 of territory and 250 million dollars in financial compensation in return for the right to develop the project

James Bay Project: Environmental Impact • Caniapiscau and Eastmain rivers were diverted into La Grande River watershed • 11, 000 km 2 of Boreal forest was submerged • Flow of La Grande River doubled

La Grande Rivière

James Bay Project: Mercury • Before the project, local levels of mercury in lakes and rivers were high due to atmospheric pollution and the natural geology of the region • When a reservoir is created the existing vegetation and soil is submerged, causing it to decompose and deplete oxygen from the water supply • Mercury that exists in a harmless inorganic form in the soil may be transformed by bacteria into methyl mercury once the soil is flooded • The toxic methyl mercury is lethal to the fish and can be absorbed and passed up the food chain

James Bay Project: Mercury • Mercury concentrations in benthic insects, fish (which feed on benthic insects), and nestling tree swallows (which feed on fish) increased after flooding • Many native people in villages where fish are a main component of the diet have shown symptoms of mercury poisoning • Mercury concentrations in fishery resources of reservoirs may remain substantially elevated for decades after flooding

Mercury in fish in La Grande 2 reservoir

Mercury in fish in La Grande 2 reservoir