What is a pesticide?

As part of our new farm to fork theme, we take a look at how our food is produced before it reaches our tables! This month, we focus on pesticides, which are used all around us in our homes and gardens, schools, and our farmer’s fields.

The word ‘pesticide’ is a general term for a chemical or biological agent that deters or kills pests, fungus, bacteria and weeds. Insecticides, herbicides and fungicides, as you can probably guess, are types of pesticide especially designed to target insects, weeds and fungus respectively.

Pesticides aren’t just used on farms. You’ll also find them in household cleaners, hand soaps and even swimming pools.

You might think that pesticides are a relatively new invention. In fact, the theory of using chemicals on farms dates back to the 1800s although it wasn’t until 1939 that things really started to change. Swiss chemist and Noble Prize-winner Paul Muller discovered one of the first major pesticides: dichlorodiphenyltrichloroethane or DDT. It was hailed as a miracle!

Initially used by the US military to control the spread of disease during the Second World War, DDT was released from military control when the war ended and made available for agricultural use, becoming widely relied upon over the next decade.

Not only was it toxic to a range of pests, it was also insoluble which meant that it didn’t get washed away. On top of this, it was inexpensive and very easy to apply.


The 1940s and 50s are now considered to have been the start of the pesticide era. The war was over, farms were more productive and food became cheaper. “DDT is good for me-e-e!” sang a group of cartoon animals, vegetables and people in an ad promoting the chemical in Time magazine in 1947.

However, as time went by, reports began to suggest that DDT was not so ‘good for me-e-e’ after all. Research began to link pesticides to poisoning, cancer and other illnesses brought about by misuse of the chemicals. In 1962 Rachel Carson published her famous book Silent Spring which argued that the effects of pesticides were rarely limited to crop pests. In fact, pesticides could actually be having a detrimental effect on the environment and human health.


Silent Spring had a powerful impact and kick-started the environmental movement against the indiscriminate use of pesticides in farming.  By 1972, activist groups had secured a phase-out of DDT in the US. Agricultural use of DDT was eventually banned worldwide by the Stockholm Convention in 2001, although it continues to be used in some countries for controlling malaria and other diseases.

Enter, the organic farming movement. In 1972, the International Federation of Organic Agriculture Movements (IFOAM) was established to regulate and legally enforce certified organic standards around the world. Organically produced food, it was argued, offered the best way to reduce your exposure to pesticides and protect the environment. Today, UK organic farming allows just 15 pesticides to be used under restricted circumstances. They are derived from natural ingredients like citronella and clove oil. Non-organic farming routinely uses 320 pesticides. Use of pesticides is monitored by the UK government’s Food Standards Agency, which considers that current levels of pesticide residues in the UK food supply do not present a significant concern for human health.

In March 2017, an article was published in the Daily Mail by Dominic Lawson which claimed that organic can actually be bad for your health and the planet. One of the arguments put forward is that organic farming produces a lower yield, therefore requiring more natural habitats to be turned over to agriculture in order to produce enough food to feed a growing population. What Lawson may be missing however, is that organic farming alone is not going to negate the environmental impact of global food demand. If we are to treat our planet and indeed our health responsibly, we have to change our diet, our habits and the very nature of our food industry.


Organic might only make up 1.5% of the overall food and drink market in the UK but the recently released Soil Association Market Report shows the organic market has grown by 7.1% – with organic food sales now outperforming non-organic food in growth terms. Whether you’re an organic convert or sceptic, it’s hard to ignore the recent success of the organic market.

Interestingly, Rachel Carson didn’t call for an outright ban on DDT or other pesticides. She simply argued in Silent Spring that their indiscriminate overuse would ultimately create resistance to pesticides, making them useless in eliminating pests. It looks like her predictions were accurate. In the 1940s, US farmers lost 7% of their crops to pests. Since the 1980s, loss has increased to 13%, even though the number of pesticides available has increased. It’s now thought that up to 1,000 insects and weed species have developed pesticide resistance since 1945. As the global population grows, we need to find a farming system that can address the many challenges we now face.

So do we need pesticides? And would it truly be possible to live in a world without them? Is a pesticide a vital protector of crops or an environmental disaster? Perhaps the truth lies somewhere in between.


Katie Roche

Katie Roche

Katie is editor of The Food Assembly blog. She enjoys writing about community, food, sustainability and how it all fits together.