The biggest source pollutants of food can be in the home itself!
The biggest risk, particularly to children, is from old medicines and household and garden chemicals. Remove all old and unmarked tins, jars and bottles and take them to your local waste point for safe disposal. Don't reuse old containers for food. Only food grade plastic or glass containers should be used. Other grades may leach toxic substances into the food. Antique crocks may look fine but they can leach lead or other heavy metals from the glaze.
Make sure that all lead pipe has been removed from the water supply, particularly where old pipes join the house to the main supply.
A water filter jug can improve the quality of drinking water as well as the taste.
Don't eat produce grown beside a busy road. This can accumulate lead and other toxic compounds from the remains of fuel, rubber and brake linings.
Take extreme care when applying pesticides to home grown produce. It is very difficult to get a uniform coverage at the absolute minimum level needed to just kill the pests.
The danger from pesticides on produce purchased from a supermarket is tiny by comparison.