The Organics Council screened organic eggs from three UK supermarkets (Sainsbury’s, Marks & Spencer's and Ocado) for 600 substances at the start of April.
Testing found cyromazine in a single organic egg sample of ‘Ocado Organic Eggs 12nos’.
Tentamus Group in Germany, an ISO 17025 accredited lab, analysed the samples.
Cyromazine was detected at 0.13 mg/kg that exceeds the maximum permitted pesticide residue level of 0.01 mg/kg for bird eggs in the EU.
Organic egg samples were analysed according to the PV-SA-085 method for multi-residue pesticide analysis with cyromazine detection by LC-MS/MS screening (LoQ = 0.010 mg/kg).
Cyromazine is not approved for use in poultry feed in the UK. Organic foods occasionally contain traces of pesticides at low levels due to environmental contamination.
It is an insect growth regulator (IGR) used to control some insect pests in fields and greenhouses.
An Ocado spokesperson said all its organic products adhere to stringent organic guidelines.
“We take the quality and integrity of all our products extremely seriously and ensure our supply chain meets our high expectations. Whilst we have found no evidence to support the claims made we take these allegations extremely seriously. We are working with our suppliers to investigate thoroughly."
While cyromazine residue detection may be expected in conventional food (within defined MRLs) contamination of organic food is unacceptable, said the Organics Council.
“The detection of cyromazine in a single organic egg sample does not suggest widespread use of non-approved synthetic pesticides by the organic poultry industry.
“However, it raises significant questions about the effectiveness of current methods used to separate and segregate organic and conventional farming environments, such as boundary zones, save it was not the result of the deliberate organic farming malpractice.”
The Organics Council said eggs were a matrix picked randomly in the blind test but it expected to find some contamination given the fipronil scandal.
The group added it did not know if eggs were of UK origin or not.
Organic farming regulatory framework
Dr Esme Purdie from the Organics Council said use of synthetic and potentially harmful substances in poultry and livestock farming is of concern in general.
“However, when organic produce fails to meet even the conventional farming safety guidelines, due to contamination with pesticide residues, it is even more alarming. This calls into question the efficacy and robustness of statutory organic farming regulatory framework.”
The Soil Association said it was unable to comment on validity of the findings due to the lack of detail.
“Key information needed to make sense of any testing for contamination includes: sampling protocols, sample integrity, statistical relevance of results of sampling, and scientific interpretation of the results.”
The Soil Association’s certification body carries out inspections and awards organic certification to farms and businesses that meet certain standards. It licenses more than 70% of the organic food on sale in the UK.