A lot of people who smoke marijuana for long periods of time often become 'slower' to things that would normally be like instant reflexes. Say your child is in bed but suddenly starts choking. If you are high, sometimes you can't notice that right off because the sound is far off or your reaction is just slow in general. That's why social services are against that as well.

My dad is a recovering alcoholic and my mom a pot head. I was born on a feeding tube the first two months of life because my mom smoked during her whole pregnancy. I had lung problems and couldn't breathe well on my own nor could I clamp on to my mothers breast, so I couldn't eat on my own either. I have a lot of health issues still that I have to take medication for... But I was taken away from there, and when they got me back I was taken away again at 6 years old for my mom still smoking pot. She's quit since, though. She knew third strike and she was out for good and her parental rights would be taken away.