Scientists in Australia are looking at fish larvae there as if they have two heads—because they do.

Millions of larvae in the country’s Noosa River were found to have grown two noggins, and chemicals from a nearby macadamia nut farm may be to blame for the defect.

"Fish don't have two heads, they generally have one,” Acting Premier Paul Lucas tells today’s edition of The Australian newspaper. “Let's find out why that is the case.”

One of two commonly used farming chemicals—the insecticide endosulfan or the fungicide carbendazim—may have caused their disfiguration, according to the Courier Mail. The chemicals could have ended up in the river through spraying or runoff, Matt Landos, a lecturer in aquatic animal health at the University of Sydney, told the newspaper. The Noosa River is in the southeast section of the state of Queensland, which spans the northeast quadrant of Australia.

Landos told the Courier Mail that “it certainly looks like the fish have been exposed to something in the river," adding that he "wouldn't like to be having kids and living next to a place that uses these chemicals." Authorities have not found any toxins in the river but are still running tests, Lucas told The Australian.

The European Union is set to ban Carbendazim, according to France 24. U.S. registration of its parent compound, Benomyl, was cancelled in 2001 by manufacturer DuPont after farmers sued over crop damage. Benomyl was found to cause an abnormal number of chromosomes, reduced sperm counts and weight loss in lab rats.

Endosulfan is banned in the EU, New Zealand and parts of Asia and Africa, according to Australian media reports, and the Environmental Protection Agency is seeking comment on petitions to nix it in the U.S. The chemical has been linked to hyperactivity, nausea, dizziness, headache and seizures in humans, and kidney, liver and testes damage in animals, according to the federal Agency for Toxic Substances and Disease Registry.

"These chemicals mess up cell development," Landos said. "There's no other plausible explanation for what's going on."

For more on chemical contamination and its potential effects on health, check out this piece on the world’s most polluted places.

Map of Australia/CIA via WikiMedia Commons