United States House of Representatives member Jared Huffman and 12 other lawmakers have requested the Environmental Protection Agency, or EPA, assess crypto mining firms potentially violating environmental statutes.

In a letter addressed to EPA administrator Michael Regan on Wednesday, Huffman said he and other Democratic House members had “serious concerns” around crypto firms in the United States reportedly contributing to greenhouse gas emissions and not operating in accordance with either the Clean Air Act or the Clean Water Act. The lawmakers identified efforts to “re-open closed gas and coal facilities” as a means to produce energy for crypto mining operations as a particular area of concern, as well as “energy-inefficient” proof-of-work mining for Bitcoin (BTC), Ether (ETH), Monero (XMR), and Zcash (ZEC).

“Cryptocurrency mining is poisoning our communities,” said the letter. “The rapidly expanding cryptocurrency industry needs to be held accountable to ensure it operates in a sustainable and just manner to protect communities.”

@RepHuffman is right: @EPA must address pollution caused by digital currencies like #Bitcoin. #ChangeTheCode #CleanUpBitcoin https://t.co/3WVBQxNuXQ

In addition to air and water pollution as a result of energy production, the U.S. lawmakers pointed to “large amounts of electronic waste” due to crypto miners becoming obsolete, and “significant noise pollution” reported around communities with mining operations in New York, Tennessee and Georgia. House members including Representative Brad Sherman — who has previously called for a ban on cryptocurrencies in the United States — and progressive lawmaker Alexandria Ocasio-Cortez signed the letter in support of action against mining firms.

“We