According to a brief article in todays paper, the EPA has announced an expanded program to warn about the chromated copper arsenate (CCA) used to pressure treat wood. Consumers should start seeing warning labels sometime this fall. The CCA contains 22% arsenic and the actual amount of CCA in the treated wood available seems to be variable, but any CCA finding it's way inside a person does not seem like a good idea.
A quick check of the EPA's website did not show any more info being available there but, apparently, this has been under discussion for some time.
With playground and picnic time upon us, this might be a good time to remind your families about it and to check your woodworking practices too. Many wells in this area have naturally occuring arsenic in the water and it seems reasonable that people in this situation are even more at risk.