Heavy metal contamination (Cu, Pb and Cd) of washed and unwashed roadside blackberries (Rubus fruticose L.)

Foraging provides a multitude of individual, social and environmental benefits. With green spaces decreasing in the UK there is the opportunity for roadside verges to become valuable foraging resources, however there is public concern over the safety of roadside forage. Human ingestion of heavy metal contaminants such as copper (Cu), lead (Pb) and cadmium (Cd) originating from traffic activity induce toxic effects in the body. Therefore, Cu, Pb and Cd maximum guideline limits for human consumption in small fruits have been established. However, studies on heavy metal concentration in roadside forage and the effect of surface washing on concentration are limited. This study examines Cu, Pb and Cd in washed and unwashed wild blackberries (Rubus fruticose L.) along a main road in Kent, UK, and compares values to maximum guideline limits. In all 44 samples, Cd concentration was well below the maximum guideline limit. Cu concentration well below the maximum daily intake in every sample if foragers were to eat one portion (80g) of berries a day, but consuming larger quantity of berries could lead to an intake above the 1mg per day limit. Washing did not significantly reduce the concentration of Cu (p = 0.174) or Cd (p = 0.752) in blackberries. Although washing significantly reduced lead concentration (p<0.001), it did not reduce the concentration to under maximum guideline limits. Thus, wild blackberries from roadside were not suitable for human consumption, although findings are not representative for all foraged berries or road networks.