Pesticide residues
Chemical substances used to protect crops from pests, whose residues on food are subject to regulatory limits and to debate about their health effects.
Pesticides (insecticides, herbicides, fungicides) protect crops. Residues can remain on or in food. Regulatory Maximum Residue Levels (MRLs) set the permitted amounts, backed by monitoring.
A fresh angle (dose, the cocktail effect and nuances): the subject is polarised between “everything is poisoned” and “there is no risk”. The reality is more nuanced:
- The dose makes the poison: permitted residues are at levels judged safe individually. The risk of acute poisoning from normal dietary residues is very low.
- The cocktail effect, the real unknown: the scientific concern is chronic low-dose exposure and mixtures of several pesticides (whose interactions are poorly studied). This is a legitimate area of uncertainty.
- Some pesticides are endocrine disruptors: certain molecules interfere with the hormone system even at low doses, an active and worrying area of research.
Organic reduces exposure (a documented benefit): eating organic significantly reduces exposure to synthetic pesticide residues (measurable in urine). This is one of the most solid benefits of organic food. A nuance: organic is not “zero pesticides” (natural pesticides are permitted).
Reducing your exposure without buying everything organic:
- Wash and scrub fruit and vegetables (reduces surface residues)
- Peel where appropriate (but you lose nutrients from the skin)
- Target organic at the most contaminated foods (“Dirty Dozen” type lists: strawberries, spinach, grapes… versus the “Clean Fifteen”: avocado, onion, thick-skinned pineapple)
- Vary origins and foods (dilutes exposure to any given pesticide)
The benefit/risk paradox: importantly, eating too little fruit and veg (through fear of pesticides or because of cost) is a far better-established health risk than the residues themselves. It is better to eat conventional (washed) fruit and vegetables than none at all. The benefit of plant foods outweighs the risk of residues.
Sources of exposure: fruit and vegetables (especially thin-skinned), cereals, animal products (bioaccumulation), water.