Sir, The primary chemical exposure of all human beings is not to traces of synthetic chemicals (“Man-made toxins are found even in the best diets”, Sept 21, and letter, Sept 23) but to the thousands of natural pesticides which we eat and consume in our fruit and vegetables every day.
Each fruit or vegetable makes its own unique complement of natural pesticides and with the novel fruits and vegetables currently available in supermarkets, the risk is increased again.
Toxicologically the majority of natural pesticides test as carcinogens; others are nerve toxins, oestrogen mimics, teratogens, chromosome breakers, allergy inducers or damage the blood, skin or thyroid.
These are precisely the same toxicological properties of synthetic chemicals that concern WWF, but natural pesticides are consumed in amounts many tens of thousands of times higher than any synthetic traces. Mankind is not adapted to these natural chemicals; at the appropriate dose they will damage and have done so in the past.
Against this enormous toxic natural background, traces of man-made chemicals are of little or no consequence, but the risks of additive or synergistic effects of natural chemicals are also thousands of times higher.
Professor in Plant Biochemistry
University of Edinburgh