Hundreds of Peruvians affected by a toxic spill are considering taking considering legal action against the Antamina mining company. Antamina is the world’s third largest copper producer and is majority owned by the British- Australian firm BHP Billiton and the Anglo-Swiss natural resource giant Glencore-Xstrata.

More than 350 people were affected after a pipeline burst in July 2012 in the northern highlands of Cajacay, Ancash. Some report continuing health impacts, such as stomach and sight problems among their children. In June of this year the company was fined US$77,000 by the Peruvian state for the spill, which critics said was an inadequate penalty for the damage caused.

Results from tests conducted by the Peruvian health authorities following the spill have been newly released following a freedom of information request submitted by La Republica newspaper. They show that, of those tested from the worst-affected Santa Rosa community, a third of children and 3 per cent of adults had elevated levels of copper in their blood.

Antamina has said that the levels of metals detected in the blood samples are typical of the area and not the result of the spill. The company also says that the Peruvian authorities are using old standards that have since been revised upwards.

However some of those tested exceed even the new, higher limits. A subsequent official study comparing results from Santa Rosa with inhabitants of the district capital, Cajacay, found that blood levels of copper were higher in Santa Rosa.

Toxicologist Carlos García Bustamente told La Republica newspaper that the results are sufficient to merit further investigation.