These people fear the bill collector more than the Grim Reaper.
Among workers ages 40 and 50, nearly half fear the financial consequences of a critical illness—compared with just 29 percent who rate dying as their biggest concern, according to a new study.
That fear of a hit to the wallet being a bigger concern than dying is most pronounced among single workers, single women and single parents, according to the Sun Life Financial survey, "Well-Placed Fears: Workers' Perceptions of a Critical Illness."
For example, single women in that 40-50 age group who earn less than $50,000 are four times more concerned about the financial fallout of a critical illness than they are worried about being killed by it, the report found.
(Read more: For millions of workers, getting sick doesn't pay)
And most single parents and single women ages 22 to 39 in that income bracket are more worried about paying the bills from those illnesses than dying from them.