The chief culprit seems to be herbicides containing the chemical 2,4-D doubled the risk of CML when dog owners used 2,4-D four or more times per year. Certain breeds, including Beagles, Scottish Terriers, Shetland Sheepdogs, West Highland White Terriers, and Wire Hair Fox Terriers are more susceptible due to a genetic predisposition to bladder cancer. Exposure to the chemicals can come from ingestion, inhalation, or contact with skin, and the amount of time needed to restrict pets from a sprayed area has not been determined. Worse, there is evidence that the chemicals can travel into the house as people and pets cross the lawn. Apparently removing shoes and limiting time on the lawn.
This is something to keep your eye on. Keep your pets healthy!