Pesticides are far from being a new invention. In the Odyssey, Homer describes how Odysseus “cleanses all pollution” by applying sulphur, while Pliny the Elder recommended using arsenic as an insect-killer, as well as mixing it with boar’s liver to cure “carbuncles upon the generative organs”.
We have since learned a lot more about what has an adverse effect on our health, while modern science can mix chemicals in combinations the Romans and Greeks could never have dreamed of. So, just how bad are today’s pesticides – and what can you do to mitigate their effects on your health?
To be clear, plenty of pesticides don’t pose any risk to humans. Caffeine is an insecticide, produced by plants for self-protection; many of us glug down a dose that would be fatal to mosquito larvae three times a day. The first real question is: how worried should you be about the less natural stuff going on your food?
“The most important thing to understand is that pesticides and their use are carefully regulated in the UK,” says Prof Michael Eddleston, a clinical toxicologist who sits on the UK Expert Committee on Pesticides. “Therefore, the amount of pesticide in and on food grown in the UK is likely to be low and not dangerous. Crops imported from abroad may be contaminated with higher amounts of pesticides, but supermarkets do their best to reduce contamination and to remove hazardous pesticides from the food production chain. So, overall, the direct risk to our health is probably low.”
One problem is that pesticide safety evaluations examine only the toxicity of individual chemicals. There is little understanding of how mixtures of chemicals behave, so the long-term effects of consuming small amounts of several pesticides as residues in food – and the possible combined effects of these residues with other environmental contaminants – are not well understood. “The general thinking is that risks from very low concentrations are small, since healthy adults are able to process and excrete toxins pretty efficiently,” says Eddleston. “But children and unhealthy adults may be more vulnerable.”
What should you do? The benefits of organic food are not clear-cut. One recent study in the US found that levels of glyphosate (a probable carcinogen) found in participants’ bodies dropped 71% after just one week of switching to organic. But, of course, even “natural” pesticides can be nasty. Arsenic and nicotine are natural, but banned for use as pesticides. There is some evidence that organic food is healthier generally, but that might be related to other factors, such as its nutrient profile.
Running your apples and broccoli under the tap isn’t a surefire solution. The UK’s Food Standards Agency notes that “washing … may help remove residues of certain pesticides”, but when pesticides are used in the germination process (when the seeds are being planted), washing later won’t do anything to help. The same is true of peeling, but, in any case, doing this removes some of the food’s nutritional value, which may cause more problems than it solves.
Perhaps the biggest concern about pesticides isn’t for us as individuals, but rather humans as a collective. “Insecticides kill off-target insects [insects that they aren’t intentionally trying to kill], affecting biodiversity, which is hugely important for future food production and the planet,” says Eddleston. “Insecticides, fungicides and herbicides also harm the soil microbiome, which is essential in making nutrients available to plants and in breaking down organic matter: two functions that are fundamental for the sustainability of food production and soil conservation, which in turn is an essential component of climate change mitigation.”
This means that we need to reduce pesticide use, in the UK and globally, through “integrated pest-management” tactics, such as producing pest-resistant crops and rotating crops to deter insects, says Eddleston: “This needs to be accelerated and pesticide use further reduced worldwide. This will not only improve food safety, but also ensure the continuity of food production, which currently and in future largely comes from land-based production. Pesticides kill indiscriminately and the world needs biodiversity for its future.” Even Odysseus, not the world’s biggest softy, would probably approve.
