Common Sense Gardening Group response to IARC classification of 2,4-D

A sub-committee of the World Health Organisation, the International Agency for Research on Cancer (IARC) has recently classified the active ingredient 2,4-D as ‘possibly’ carcinogenic to humans. The Common Sense Gardening Group of the Crop Protection Association has issued the following statement in response.

Many independent experts disagree with these classifications on the basis that no new research or data was used, the most relevant, scientific data was excluded from review, and the conclusion did not appear to be supported by the scientific data.

IARC’s reviews are limited and the process is designed to result in ‘possible’ and ‘probable’ classifications. IARC’s assessment of 2,4-D is similar to their assessment of other everyday items such as coffee, mobile phones, aloe vera (whole leaf extract), pickled vegetables and occupations including hairdresser, carpenter and chip shop worker, all of which fell into these categories.

IARC reviews seek to identify cancer hazards, meaning the potential for the exposure to cause cancer. However, it does not indicate the level of risk associated with exposure. The cancer risk associated with substances or agents assigned the same classification may be very different, depending on factors such as the type and extent of exposure and the strength of the effect of the agent.  This distinction between hazard and risk is important. An agent is considered a cancer hazard if it is capable of causing cancer under some circumstances. Risk measures the probability that cancer will occur, taking into account the level of exposure to the agent.

Claims that 2,4-D is ‘possibly’ carcinogenic also contradict conclusions reached by the IARC’s own parent body the WHO and the Food and Agriculture Organisation (FAO) through their Joint Meeting on Pesticide Residues (JMPR), which has reviewed 2,4-D five times, most recently concluding that there is no evidence of carcinogenicity.

IARC itself has admitted it decided on the ‘possibly’ carcinogenic classification because there was "inadequate evidence in humans and limited evidence in experimental animals" of ties between 2,4-D and cancer.

Gary Philpotts, Chair of the Common Sense Gardening Group said:

“It’s important to note that 2,4-D is amongst the most thoroughly tested and evaluated herbicide products on the market. Numerous health assessments conducted by public authorities over 70 years have consistently concluded that 2,4-D does not pose an unacceptable risk to public health.

“Human health and responsible use of garden care chemicals is and must always be our highest priority. As an industry we take pride in the detailed submissions we provide to regulators and the extreme rigor with which our products are assessed. Gardeners and the general public should rest assured that these products are safe and effective when used according to the instructions on the label.”

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