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Press Release

U.S. Minerals, Inc. admits Clean Air Act violation for exposing employees to arsenic at Anaconda plant

For Immediate Release
U.S. Attorney's Office, District of Montana

MISSOULA – U.S. Minerals, Inc., a corporation accused of exposing employees to elevated levels of arsenic at its Anaconda facility, today admitted violating the Clean Air Act, said Acting U.S. Attorney Leif M. Johnson.

In addition, U.S. Minerals has agreed to settle a related civil case regarding violations brought by the Department of Labor’s Occupational Safety and Health Administration (OSHA).

U.S. Minerals pleaded guilty to one count of negligent endangerment, a misdemeanor, under the Clean Air Act as charged in a criminal information. The corporation faces a maximum penalty of five years of probation and a fine as determined through statute.

Under the terms of a plea agreement in the criminal case, the government and U.S. Minerals will jointly recommend to the Court that the company be placed on probation for five years and pay a $393,200 fine. The agreement recommends probationary conditions in which U.S. Minerals will implement a nationwide environmental health and safety plan that applies to all of U.S. Minerals’ facilities throughout the United States and a medical monitoring program for current and former employees who have been exposed to elevated levels of arsenic during their work at the Anaconda plant, which has ceased operations.

U.S. Minerals also has agreed to resolve a related civil case brought by OSHA, alleging 19 serious health and safety violations with a total penalty of $106,800. Under the terms of that agreement, U.S. Minerals will accept all citations as issued and pay the penalty as assessed.

U.S. Magistrate Judge Kathleen L. DeSoto presided. Sentencing in the criminal case was set for Dec. 10 in Butte before U.S. District Judge Dana L. Christensen.

“Throughout Montana’s long history with mining, operators like U.S. Minerals have sacrificed worker safety for profit.  These operators need to know that there are severe consequences to this kind of callous behavior.  This is an important case because it not only holds the operator criminally responsible for poisoning its own workers, but it also prevents U.S. Minerals from doing this again anywhere in the country.  I want to thank Assistant U.S. Attorney Ryan G. Weldon, Special Assistant U.S. Attorney Eric E. Nelson, the Environmental Protection Agency’s Criminal Investigation Division, the Department of Labor, Office of Safety and Health Administration, the National Institute for Occupational Safety and Health, and the Montana Department of Public Health and Human Services for their diligent work on investigating this case and bringing these wrongdoers to justice,” Acting U.S. Attorney Johnson said.

“This case demonstrates that EPA and its federal law enforcement partners will hold companies accountable when they engage in conduct that places their employees in danger from exposure to airborne releases of hazardous air pollutants such as arsenic,” said Lance Ehrig, Special Agent in Charge of EPA’s criminal enforcement program in Montana.  “The criminal and civil penalties serve to provide deterrence, and the 5-year national compliance plan requires U.S. Minerals to implement an inspections, training and auditing program to ensure a safer working environment at all its facilities. Finally, and importantly, health monitoring will be assured for current and former employees at the U.S Minerals Anaconda facility that were exposed to airborne arsenic.”

“The employees of U.S. Minerals were finally given the justice they deserved through a joint effort between the Environmental Protection Agency, the United States Department of Justice, and our staff at the Occupational Safety and Health Administration. Working together, we were able to leverage our resources and hold U.S. Minerals accountable for overexposing employees to inorganic arsenic and violating multiple federal laws,” said Galen Blanton, Regional Administrator for OSHA’s Denver Region 8.

The government alleged in court documents that U.S. Minerals, which has multiple facilities throughout the United States, manufactured silicate abrasive, a substance sold to industrial and governmental customers.  Raw materials used in the production process were obtained from a copper slag pile located within the Anaconda Superfund site. The government further alleged that from July 2015 until February 2019, U.S. Minerals negligently released into the air inorganic arsenic, a hazardous air pollutant, and exposed employees. Exposure to arsenic is known to cause lung and skin diseases, including an increased risk of skin cancer, and may also cause cardiovascular effects and other cancers.

The government further alleged that in July 2015, National Institute for Occupational Safety and Health (NIOSH) inspected the site, collected air samples from throughout the outdoor facility and conducted personal monitoring of employees on site.  An analysis determined employees were exposed to levels of arsenic and lead, which exceeded both NIOSH and OSHA exposure limits, and that there were high levels of arsenic and lead in the ambient air.

In late 2015, OSHA inspected the facility and found numerous violations of health and safety standards. The violations included employees being exposed to inorganic arsenic at levels that ranged between 1.25 and 4.75 times the OSHA permissible exposure limits. As a result of the inspection, OSHA issued 19 serious violations with penalties totaling $106,800.

The government also alleged that in April 2018, the Montana Department of Public Health and Human Services learned of a U.S. Minerals employee diagnosed with arsenic poisoning at a local hospital. Over the next few days, the state learned of three additional U.S. Minerals employees who had high levels of arsenic in their urine. State officials conducted a site visit in June 2018, noted “apparent inhalation hazards” and shared their findings with U.S. Minerals. A second inspection in October 2018 found the previous violations had not been addressed and that employees were still exposed to hazards.

In addition, the government alleged that on Feb. 20, 2019, after the investigation discovered numerous employees with high levels of arsenic, the state issued an order for U.S. Minerals to cease and desist operations until it implemented controls and protected its workers. The state lifted the order and allowed U.S. Minerals to resume operating in March 2019 under certain conditions. One of those conditions required U.S. Minerals to provide the state with quarterly medical monitoring reports related to arsenic and lead testing results on employees. Documents provided by U.S. Minerals to the state showed there were still employees who periodically tested high for arsenic and lead.

Assistant U.S. Attorney Ryan G. Weldon and Special Assistant U.S. Attorney Eric E. Nelson are prosecuting the criminal case, which was investigated by the Environmental Protection Agency’s Criminal Investigation Division, OSHA, NIOSH, and the Montana Department of Public Health and Human Services. The U.S. Department of Labor’s Office of the Solicitor is litigating the OSHA matter.







Clair J. Howard
Public Affairs Officer

Updated August 23, 2021