Is it okay for toddlers to eat pesto/other basil-containing foods regularly? is the estragole component of any risk?

Basil and pesto: In general, there does not seem to be a risk to humans related to consumption of foods containing estagole compounds. Research related to carcinogenicity is in mice at high doses, not at intermittent low doses consistent with human consumption. Pesto-containing food ingested intermittently should be safe for a toddler.

For Flavor: A small amount added to their regular diet on occasion should be safe. A standard brand or variety would be a good selection. I advise waiting three days after ingestion of the basil to ensure that there is no allergic reaction to the herb, before introduction of another new food.