Celery has topped a new list of foods which are most likely to contain pesticide residues.

The 'dirty dozen' list has been compiled by food and soil researchers using data from the Food Safety Authority.

Celery is closely followed on the list by peaches, apricots, butter and bread, in which researchers identified 23 pesticides.

Close contenders behind the dirty dozen were cucumber, nectarines, lettuce, tomatoes, wine and pears.

Safe Food Campaign researcher Alison White says consumers are often reassured that because pesticide levels are below a certain level, the food is assumed to be safe, but she says the combined effect of all the chemicals in food is really not known.

What we do know is that there are various serious long term effects associated with particular pesticides that are found in our food, including endocrine or hormonal disruption, cancer, immune system suppression, nervous system damage, genetic damage and birth defects.

We also know that various pesticides used to grow food have damaging effects on wildlife and the ecosystem.

Ms White says there is plenty of good science showing that combinations of pesticides can have more of a toxic effect at low levels, than single pesticides by themselves.

Washing and peeling could reduce some residues, but she advised anyone with a compromised immune system, pregnant women and young children to eat organic foods.

The top 12 food products to contain pesticide residues were:

1. Celery
2. Peaches
3. Apricots
4. Butter/cream/cheese
5. Wheat, including bread
6. Apples
7. Plums
8. Mandarins
9. Raspberries
10. Oranges
11. Strawberries
12. Grapes/raisins/sultanas