Nitrate Surveillance Monitoring Program Annual Report (April 2022 to March 2023)
Authors:   Food Standards Agency,   RSK ADAS Ltd.
Published: December 2024

This is the 2022-23 data for the project FS101228 - Nitrate Surveillance Monitoring Program. Previous reports are available:

<a href=“https://doi.org/10.46756/sci.fsa.uau489” style=“display: inline-block; padding: 10px 20px; background-color: #007d75; color: white; text-align: center; text-decoration: none; border-radius: 5px;”>Nitrate Surveillance Monitoring Program (Annual Report May 2021 - March 2022)</a>

<a href=“https://www.food.gov.uk/research/chemical-hazards-in-food-and-feed/nitrate-monitoring-in-spinach-and-lettuce-surveillance-programme” style=“display: inline-block; padding: 10px 20px; background-color: #007d75; color: white; text-align: center; text-decoration: none; border-radius: 5px;”>Nitrate monitoring in spinach and lettuce - surveillance programme</a>

#Summary

While the UK is no longer part of the EU, monitoring activities have continued under GB retained law 1258/2011 since January 2021. The requirement to carry out monitoring for nitrate in lettuce, spinach and rocket is being met by the UK Nitrate Surveillance Programme. Results are presented for the period between 1 April 2022 and 31 March 2023.

The survey monitors compliance in UK and gathers data on occurrence levels in leafy green vegetables. This report covers the survey period 2022 to 2023. The current round of surveys commenced in 2020.

This surveillance has been undertaken since May 1996, except for 2019-20, and reported in earlier MAFF (now Defra)/FSA Food Surveillance Information Sheets. Monitoring of UK grown lettuce, spinach and rocket is currently led by RSK ADAS Ltd (ADAS) in partnership with NRM Laboratories.

The survey monitors compliance in UK and gathers data on occurrence levels in leafy green vegetables. The survey period covers the years 2022 to 2023. The survey commenced in 2020.

A total of 200 samples were collected within the sampling period, comprising of 120 lettuce, 18 rocket, 21 spinach samples. A further 41 samples categorised at ‘Other Green Leafy Vegetables’ was comprised of samples including chard, Chinese leaves, mizuna, kale, and pak choi. The lowest average nitrate concentration was recorded in summer-grown iceberg lettuce (1045.1 mg/kg). One iceberg sample exceeded the maximum nitrate concentration. The highest average nitrate concentrations were seen in ‘other leafy green vegetables’ (7701.3 mg/kg) and in summer-grown rocket (7235.7mg/kg).

The number of samples exceeding the maximum levels decreased this year to 6 samples – one sample of Iceberg, two samples of open-air non-iceberg lettuce sampled in the summer, two samples of rocket sampled in the summer and two samples of spinach. A further 14 samples were within 10% of the maximum level. Historical trends indicate that the average annual nitrate concentrations were again elevated for rocket and spinach, and the proportion of samples that exceeded the maximum level increased.

Consistent with previous years of this project, a strong correlation was found between nitrate concentration and sampling date, with samples collected later in the season showing greater concentrations, indicating potential interactions between nitrate accumulation and climate, particularly light levels, available soil moisture and any accumulation of nitrate in the soil. 2022-23 was warmer (particularly during the summer), with less rainfall and more hours of sunshine than in previous years.