: Prolonged exposure is a major problem but intense single exposures are
: dangerous too.

: This is a sensitivity issue, once you reach your tolerance you can not have
: ANY further exposure for the rest of your LIFE!!

From past experiences with isocyanates in the workforce:

1. Sensitivity is a genetic issue, some people have better genes. Life can change if you happen to be the poor individual that was on the wrong end. Just because George didn't have a problem, is no guarantee that you won't. Roll the dice.

2. The "ANY" above is relative, depends upon your tolerance for an inability to breath or not be concerned with chemical burns (direct physical contact) that look like someone has been using you to put out cigarettes.

Always minimize your contact. The time between cause and effect isn't as quick as with guns and bullets. Acceptable levels of exposure to chemicals (OSHA) always seem to decrease, not increase, over time.