Rick, I can't speak for boatyards, past history or "I used it, and I still can spell my name" kind of stories, but regular use in the US requires biological monitoring (a urine test at the end of each shift). It's use also requires air monitoring with no more than 200 parts per million in the air during an eight hour shift, but if at any point the rate increases to 300 parts per million, the work must stop until the lower rate is achieved. In carcinogenicty it is classified as "A3" in several forms as a known animal carcinogen. These limits are set by the American Conference of Governmental Industrial Hygienists (ACGIH), which is one of the source agencies used for setting limits on the use of chemical compounds in the US.

I note with amusement that the US, which is generally castigated for actually publishing standards, and legislating their use (to the cheers or boos of millions), comes off as alarmist in this case, but then again, I've often regarded inappropriate chemical use as a self correcting IQ test.