The Biden administration is facing mounting pressure to confront a surge in imports of possibly fraudulent used cooking oil, with lawmakers now highlighting the use of third-party certification to help block fake supplies from entering the US.

While big importers are known to use testing and third-party certifications to ensure the legitimacy of used cooking oil, or UCO, foreign renewable fuel producers and other companies appear to be escaping that scrutiny and harming domestic fuel producers, 11 Republican US House members wrote in a letter to Environmental Protection Agency Administrator Michael Regan. 

“We have significant concerns that the administration has not held other actors to the same traceability and integrity standards,” according to the newly released July 25 letter. EPA spokespeople did not immediately comment on the matter.

The push follows concerns expressed by a bipartisan group of US senators last month, underscoring rising alarm in the nation’s capital over biofuel policies at a time when low-carbon fuel markets are quickly expanding across the globe, and US producers are suffering. 

US processors of soybeans say used cooking oil imports are undercutting American crops used for biofuels, and they have pushed for higher levies on UCO imports from China. Even beyond the import flood, there’s been widespread speculation used cooking oil from Asia is mixed with fresh vegetable oils, potentially distorting commodity values, undermining US biofuel laws and leading to deforestation.

Crop trader Archer-Daniels-Midland Co. said Tuesday its second-quarter profit from processing soybeans into meal and oil was hurt in part by increased competition from imported used cooking oil, though Chief Executive Officer Juan Luciano added that the company is seeing some “significant moderation” of the situation.

The lawmakers also noted that even as renewable diesel capacity has risen in the US, there’s been an increase in imports of such fuels made in Singapore and elsewhere. That rise, combined with “lackluster” US biofuel-blending targets for the green diesel industry, is hurting domestic fuel makers, they said. 

The lawmakers, including Mariannette Miller-Meeks and Zach Nunn of Iowa, asked how the EPA differentiates between UCO importers with International Sustainability and Carbon Certification and those without.