While confidentiality rules preclude NFL or team officials from divulging the nature of a four-game suspension levied against Kansas City linebacker Lew Bush on Wednesday evening, ESPN.com has learned that the sanction is the result of a positive test for the stimulants ephedrine and Ma Huang.

Several sources close to Bush confirmed the Chiefs' 10-year veteran tested positive for the banned substances several weeks ago and that the ephedrine came in an over-the-counter supplement once sold by a national chain.

The product, "Pro Performance/Pro Orange," has been pulled from shelves.

According to several sources, ephedrine and Ma Huang were not listed on the label of the supplement, and Bush will appeal the suspension on those grounds. He will present affidavits from officials of the national chain supporting his claims of ignorance and acknowledging the mislabeling.

Given the history of such appeals, however, Bush has little chance to prevail. The rationale of the league, and even of the NFL Players Association, is that players are ultimately responsible for what goes into their bodies. The union has cautioned its members to that effect, because most supplements are not controlled by the FDA, and because labeling is often slipshod.

Bush, 32, quit using the supplement some time ago, but tested positive in a random and routine screening. In fact, Bush had to scramble to find a bottle of the supplement in an attempt to obtain the label as evidence in an appeal.

The league began testing for ephedrine this summer and the ban received plenty of accompanying publicity. It is not known if Bush is the first player suspended for ephedrine, since the NFL does not announce the banned substance which precipitated sanctions.

His suspension, which begins immediately, was generically announced as a violation of the NFL's substance and steroid abuse policy. The linebacker will be able to return to the team on Dec. 2, following Kansas City's game against Arizona the previous day.

The suspension will cost Bush $235,294.11, four-seventeenths of his 2002 base salary of $1 million. The former Washington State standout started the first five games of the season but hasn't played since, in part because of a rib injury, eventually because he lost his starting job to rookie Scott Fujita.

Kansas City officials were aware of the pending suspension and that is one of the reasons the team last week signed second-year linebacker Quentin Caver, recently released by the Philadelphia Eagles.

Len Pasquarelli is a senior writer for ESPN.com.