Conservationists and vets are warning that plastic waste in an open landfill in eastern Sri Lanka is killing elephants in the region, after two more were found dead, AP reported.

Around 20 elephants have died over the last eight years after consuming plastic waste in the dump in Pallakkadu village in Ampara district, 210 kilometers east of the capital, Colombo.

Autopsies showed they had swallowed large amounts of non-degradable plastic found in the dump, wildlife vet Nihal Pushpakumara said.

“Polythene, food wrappers, plastic, other non-digestibles and water were the only things we could see in the post mortems,” he said.

Elephants are revered in Sri Lanka but also endangered. Their numbers have dwindled from about 14,000 in the 19th century to 6,000 in 2011, according to the country’s first elephant census.

They are increasingly vulnerable because of the loss and degradation of their natural habitat. Many venture closer to human settlements in search of food, and some are killed by poachers or farmers angry over damage to their crops.