U.S. Sens. Elizabeth Warren and Ron Wyden have raised concerns over Robert F. Kennedy Jr.’s financial ties to vaccine-related lawsuits and are requesting commitments to address potential conflicts of interest if he is confirmed as Secretary of Health and Human Services, according to a letter from Warren and Wyden.

Kennedy disclosed to the Senate Finance Committee that he has received referral fees from the law firm WisnerBaum for cases involving vaccine-related litigation, according to the letter. The arrangement entitled Kennedy to 10% of fees awarded in contingency cases he referred to the firm, including litigation related to the human papillomavirus vaccine, Gardasil, according to the statement. The disclosure indicated that Kennedy earned approximately $2.5 million in referral fees over the past three years, according to Warren and Wyden’s letter.

The letter stated that Kennedy remains listed as an attorney of record in at least five Gardasil-related cases, despite his statement that he resigned from the consulting arrangement. The Senate Finance Committee requested details on which cases Kennedy referred to WisnerBaum and what financial interests he retains, according to Warren’s statement.

The senators noted that Kennedy amended his ethics agreement to transfer his financial interest in the vaccine cases to an adult family member. The letter stated that this arrangement does not resolve concerns over conflicts of interest.

Warren and Wyden requested that Kennedy commit in writing to recusing himself from vaccine-related decisions and communications, including matters involving the Centers for Disease Control and Prevention and the Food and Drug Administration, according to the letter. The senators also asked Kennedy to commit to refraining from involvement in vaccine litigation for at least four years after leaving office, according to Warren’s statement.

The Finance Committee has also asked Kennedy to clarify whether he was an attorney of record in multiple Gardasil cases and amend his ethics agreement to address those matters, according to the letter from Warren and Wyden.