It’s a fraught subject. Some Captains are keen to stay low, certainly below 400+ for that reason. I used to routinely fly up to 470/490 on biz jets. 490 was the artificial ceiling imposed by the operator as at 490 or below the EASA record keeping for exposure is essentially a book keeping operation based on time flown whereas above 490 specific individual monitoring was required. I don’t know the exact details, but I can confirm that I have (currently - touch wood) healthy children despite both mid-latitude high altitude stuff and long haul northern canada/Russia.
Od course, the plural of anecdote ain’t data, you pays your money &c.