CHICAGO (WSCR) Frank Thomas has always maintained he never took steroids and for the most part, he’s been one of the few sluggers from the steroid era who is believed to be clean.

Wednesday, in an interview on 670 The Score’s Boers & Bernstein Show, Thomas said he “had no idea” steroids were being used as much as they were.

“I’ll be honest with you. It was a secret society,” Thomas said. “I had no idea. I think I was the one guy that when they were having that conversation they would stop quickly when I walked in the room. For many, many years I had a lot of teammates involved and I had no idea it was going on the way it was going on. There were always rumblings about one or two guys, but to know the numbers that really came out, I was really, really shocked.”

Listen: Frank Thomas on 670 The Score

Still, Thomas, who retired in 2009 after amassing 521 career home runs, is always going to face some doubt. He said he understands that and does not hold any grudges against the players who cheated.

“I can’t hate guys for what they did,” he said. “The money exploded in the nineties like they had never seen before. And it’s hard for anyone not to do what is best for their family. Guys got to a weak point in their lives and did what they had to do. I look back on it now and there are no grudges for me for anyone. I just wish I had known about it.”

As for his own approach while opponents cheated, he said:

“We just saw great players become amazing players. Wow, I got to witness it, I got to play against it,” Thomas said. “It wasn’t just the hitters it was the pitchers also. I went from seeing guys paint around 91-92 MPH to it seemed like the whole staff throwing above 95. The game definitely changed right before my eyes. But me being the hard worker, it was, ‘I got to work a little bit harder, these guys are catching up to me fast.’

“I’m happy to go home now and sleep very, very soundly every night not wondering if someone is going to call me to figure out what happened back in such and such and such, because I’m sure there are a lot of guys going home right now still worried”

Thomas also told Boers & Bernstein that his favorite home runs of his career came at U.S. Cellular Field, but not when he was wearing a White Sox uniform. Instead, it was when he returned to Chicago for the first time with the Oakland Athletics and homered in his first two at bats.

“My heart was always in Chicago and I never wanted to leave this place,” Thomas said. “I was struggling that year and to come home and feel like, ‘Hey, I’m home. This is my batters box. I was here when they built this stadium.’ And to hit two home runs right away it was just fulfilling to my heart because Chicago has always been a special place in my heart and it’s home for me.”