Spain's Agriculture Ministry announced on July 3 that it had halted all transport of a low-grade olive oil derivative on fears it could be dangerous for human consumption. The ministry said it took precautionary action after traces of hydrocarbons were found in oil produced from crushed olive residues, known as marc olive oil, which is sometimes mixed with other oils and used in cooking.
Regional governments issued a statement warning consumers of a potentially "serious, but not immediate, danger" because of the presence of the hydrocarbons. The statement said the hydrocarbons were "apparently" produced by the manufacturing process.
Consumers were warned to get rid of any marc olive oil they might have at home and consumers' associations called for checks on hotels and restaurants to ensure the oil was not being used. Supermarkets were withdrawing marc oil products from sale.
The authorities also warned consumers not to confuse marc olive oil with olive oil and virgin oil.
Spain, the world's largest olive oil producer, made 107,000 tons of marc olive oil in 1997, according to the last available figures from the ministry. Olive oil production itself was 1.1 million tonnes in the same year.
In the early 1980s in Spain, more than 400 people died and hundreds of others suffered symptoms including partial paralysis after eating poisonous rapeseed oil meant for industrial use. The oil was sold to the public as cut-price olive oil.