What impact does environmental pesticide contamination have on the organic food chain?

17 May 2023, Switzerland: A review by FiBL Switzerland on the current scientific literature showed that pesticides are widely present in soils, water and air and have a potential to contaminate organic produce. These contamination pathways must be considered when findings of pesticide residues are investigated.

The use of synthetic pesticides is not allowed in organic production. In order to fight cases of fraud, the organic regulation obliges all operators along the organic food chain to monitor pesticide residues in their products (EU, 2018/848). The detection of such residues causes an investigation to find the causes for the residue. The delay, the extra labour and the analyses cause significant costs.

Traces of synthetic pesticides are regularly detected in organic food and a significant share of these cases are due to environmental contamination. In order to understand the implications of environmental pesticide contamination for the organic food chain, the Research Institute of Organic Agriculture FiBL reviewed 92 scientific studies on the pesticide contamination of the environment and on how pesticides can enter the food chain from the environment.

Organic crops are at risk of contamination

The literature shows that pesticides are omnipresent in the environment. Regarding soils, a Europe-wide study found that 83 % of soils are contaminated with at least one pesticidal substance. Organically managed soils also contain pesticides. Regarding water, European streams, rivers and lakes contain traces of various pesticides, so-called “cocktails”. For example, mid-sized rivers in Switzerland contain on average 40 pesticides per sample. Regarding air, pesticides are frequently present in ambient air and are in some cases associated with long-range transportation processes.

Pesticides can enter organic crops through multiple pathways from the environment, for example uptake from soil, irrigation, deposition from the air or rainfall. Organic operators have some possibilities to reduce the risk for pesticide residues but in some situations, a certain level of contamination is technically unavoidable. Moreover, these measures come at a cost and are particularly a challenge for small operators as they require highly specialised know-how.

Case-specific investigations are adequate

What do the findings of this review imply for the investigation of residue cases on organic food? First, residue findings in organic food are not necessarily evidence for fraud.

Second, due to the risks of pesticide contamination from the environment, the organic sector is not able to meet a “zero-tolerance” for pesticide residues.

Third, a single numerical threshold value for all pesticide residues to distinguish cases of fraud from environmental contamination is not adequate. Contamination risks vary greatly between regions, crops and compounds.

A case-by-case investigation, where evidence for or against all possible origins of pesticide residues is collected, will deliver more reliable answers. Finally, it remains a challenge to determine the precise origin of residues and whether they are due fraud or technically unavoidable.

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