Elon Musk’s brain implant company is under investigation by the US Department of Transportation (USDOT) after allegations surfaced today that it may have illegally transported pathogen-laced devices removed from monkeys.

An animal welfare group raised concerns in a letter sent to the USDOT today asking it to investigate Musk’s company Neuralink “for violations of the federal hazardous material transportation law and fine it accordingly.”

Neuralink aims to develop a device capable of controlling a computer when implanted in the brain. But Neuralink already faces a federal probe following previous allegations of animal abuse and rushed experiments leading to unnecessary deaths.

The letter was penned by the Physicians Committee of Responsible Medicine (PCRM), a nonprofit organization that advocates against the use of animals in medical research. It’s the same nonprofit that alleged last year that Neuralink violated the Animal Welfare Act in its treatment of animals used to test its technology.

Neuralink poses “a serious and ongoing public health risk” by mishandling implants removed from monkeys, the group says in the letter, which was obtained by Reuters. For example, the implants may have been contaminated with antibiotic-resistant staphylococcus, herpes B virus, and other pathogens. Neuralink employees “appear to have unsafely packaged and transported” those contaminated materials, potentially because the employees lacked legally required safety training.

“We take these allegations very seriously,” a USDOT spokesperson said to The Verge in an email regarding PCRM’s letter. “We are conducting an investigation to ensure that Neuralink is in full compliance with federal regulations and keeping their workers and the public safe from potentially dangerous pathogens.”

Musk divulged in 2019 that Neuralink had implanted its device in a monkey that was subsequently “able to control a computer with its brain.” Since then, Neuralink has shown off videos of monkeys seemingly playing video games and spelling out words using the devices placed in their heads. Neuralink has also put implants in pigs.

Despite those experiments, Neuralink is way behind on its efforts to test the devices out in humans. That goal was previously slated for 2020 and has since been pushed to potentially sometime this year. Missed deadlines have reportedly amplified pressure on researchers to speed up their work at the risk of harming the animals they work with in the process. Now it seems that rush could put people at risk, too.

This month, PCRM obtained communications between Neuralink and its former partner, the University of California, Davis, about how to handle devices removed from animals. UC Davis employees “repeatedly raised concerns” about how Neuralink took and returned explanted devices from its California National Primate Research Center in 2019, according to PCRM.

“Since the hardware components of the explanted neural device are not sealed and it was not disinfected prior to leaving the Primate Center, this presents a hazard for anyone potentially coming in contact with the device. Simply labeling it “hazardous” doesn’t account for the risk of potentially contracting Herpes B,” reads one email sent in March 2019. It was sent by someone who was “likely a UC Davis employee,” according to the letter (names were redacted from the documents).  

Neuralink ultimately got frustrated with UC Davis over what it saw as slow-moving progress with animal tests and stopped working with the university in 2020, Reuters reports.

Neuralink did not immediately respond to a request for comment from The Verge. UC Davis declined to send any specific comments other than to say in an email that the university follows regulations on lab safety and biohazards.