Here’s the link.
http://www.straightdope.com/classics/a1_026.html
This column from 1975 got quoted in another thread about posting signs about non-existant hazards. I read Cecil’s column, and he seems to be saying he doubts there’s any hazard to pets from the stuff the lawn care companies plant their signs about.
The stuff they spray is usually a mix of liquid fertilizer and ordinary weed killer. That doesn’t sound scary, but the labels tell you not to get it on bare skin or ingest it. It will irritate the skin, and it can soak in through the skin. If you or I got it on our hands, we would go wash it off. Now, Cecil’s dog has probably been trained to wash his own paws, but most dogs will just lick their paws when they itch, so they’ll be licking off the chemical.
Cecil states that the hazard of contact disappears after the chemical dries. That’s true, but tomorrow morning’s dew makes it a hazard again, if no rain has happened.
When I spray the weeds in my own lawn, I wear a filter mask and waterfroof gloves. (It makes me sick to breathe the mist.) When I’m finished, I change clothes. I don’t let my dog on the lawn for at least a couple of days.