FACTBOX-Risks and causes of Irish pork contamination

(Updates cattle farms and product list, adds countries)

Dec 7 (Reuters) - The Irish government ordered the food industry on Saturday to recall all locally produced pork products from shops, restaurants and plants because of contamination with dioxin, which can cause cancer.

Ten farms in Ireland and nine in Northern Ireland had used contaminated pig feed, and both Britain and Ireland told consumers not to eat any Irish pork products, though the risk to public health was considered extremely low.

A total of 20-25 countries may have received contaminated shipments according to Irish officials, including France, the Netherlands and Belgium.

HEALTH RISKS

Authorities found the dioxin contamination in pork fat samples through the presence of polychlorinated biphenyls (PCBs), which are chemically similar to dioxin and indicate dioxin contamination.

Dioxins and PCBs are toxic chemicals that can cause cancer, hormone disruption, reduced ability to reproduce, skin toxicity and immune system disorders.

The compounds take a long time to accumulate in the body so a relatively short period of exposure has little impact.

HOW DO THE TOXINS ENTER THE FOOD CHAIN?

Dioxins are formed as by-products during burning processes.

PCBs have been used in transformers, building materials, lubricants, coatings, plasticizers and inks, though their use has largely been phased out.

Both dioxins and PCBs break down very slowly and persist in the environment, where they enter the food chain. Up to 90 percent of human exposure to dioxins results from the consumption of food containing dioxins, mainly foodstuffs of animal origin with a high fat content, since these contaminants accumulate in fatty tissues. Foodstuffs in which dioxins can occur include meat, fish, eggs and milk.

WHICH IRISH PRODUCTS COULD BE CONTAMINATED?

Pork meat, bacon, rashers, pork sausages, sausage meat, gammon steaks, offal from pigs, salami, ham, sausage rolls, black pudding, white pudding, pork pate, pork pies, ready meals, pizzas and sandwiches with Irish pork/bacon as an ingredient.

NOT RECALLED BY IRISH AUTHORITIES:

Pork gelatine, products with pork gelatine such as sweets, crisps and snack foods, sauces with pork or ham content.

HOW DID THE CONTAMINATION OCCUR?

The dioxins probably originated in by-products of baking that were dried to be used as animal feed, using fuel that was not suitable for the food industry.

Animal feed, from one source, which tested positive for dioxins was distributed to a number of pig farms and fed to the pigs.

Irish authorities are testing a further 38 cattle farms for possible contamination, but say the risk from beef is minimal as cattle are fed mainly on grass. (Source: Irish government, Food Safety Authority of Ireland, Imperial College London) (Reporting by Andras Gergely; editing by Matthew Jones)