A study by an ecological group has discovered that as many as 21 types of fish found in the Brantas River in East Java, Indonesia, have been eating plastic and disposable diapers, posing a danger to people consuming the fish.

About half-a-metric-ton of diapers were tossed into the Brantas River every year, the Ecological Observation and Wetlands Conservation (Ecoton) group said after it conducted 30 clean-ups at the Karangpilang sluice gate of the river in the past year.

Plastic fibers found in diapers were also found in the stomachs of the fish in the river, such as keting and rengkik, which are often consumed by locals, said Riska Darmawanti, Ecoton’s research manager.

When the fish swallow plastic from the polluted water, the plastics are absorbed into their flesh, he said. About three million consumers of tap water in Surabaya have also been compromised as the water is contaminated by solid waste, the group said.

Ecoton urged authorities to tackle the water pollution problem and help encourage the public to use reusable cloth diapers. East Java Governor Soekrwo urged mayors and officials at solid waste facilities to educate people to not dispose of garbage in the river.

In December 2017, Darmawanti and two other residents filed a lawsuit against Soekrwo, accusing him of neglecting the disposable diaper waste in the Brantas River, which is said to be among the 20 most polluted rivers in the world.