Heavy metal contamination (Cu, Pb, and Cd) of washed and unwashed roadside blackberries (Rubus fruticose L.)
Authors: Chamberlain Lauren K. , Scott Hannah , Beddoe Naomi , Rintoul-Hynes Naomi L. J. 
Published: July 2024

Foraging provides a multitude of individual, social, and environmental benefits. With green spaces decreasing in the United Kingdom, there is an 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, induces toxic effects in the body. Therefore, maximum Cu, Pb, and Cd guideline limits for human consumption in small fruits were established. However, studies of heavy metal concentrations in roadside forage and the effects of surface washing on concentrations are limited. This study examined Cu, Pb, and Cd in washed and unwashed wild blackberries (Rubus fruticose L.) along a main road in Kent, UK, and compares the values with maximum guideline limits. In all 44 samples, Cu, Pb and Cd concentrations were well below the maximum guideline limit or daily reference intake (RI) value. Cu and Pb concentrations were below the maximum daily intake in every sample if foragers eat one portion (80 g) of berries a day, but consuming a larger quantity of berries per day (e.g., 1 kg) could lead to an intake above the guideline limit for Cu (1 mg) and Pb (0.1 mg), but not Cd (0.03 mg). Washing did not significantly reduce the concentrations of Cu (p = 0.174) or Cd (p = 0.752) in blackberries, but did significantly reduce the Pb concentration (p &lt; 0.001). However, Pb concentration was below maximum guideline limits for every sample regardless of washing treatment. Thus, wild blackberries collected from the roadside were suitable for human consumption, although the findings are not representative of all foraged berries or road networks. Integr Environ Assess Manag 2024;20:2107–2115. © 2024 The Author(s). Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Key Points

Urban foraging is an ever-popular activity that reaps individual, social, and environmental benefits, with blackberries (Rubus fruticose L.) being a near-universally foraged product. Human ingestion of heavy metal contaminants such as copper (Cu), lead (Pb), and cadmium (Cd) originating from traffic activity can induce toxic effects in the body; therefore, maximum guideline limits for human consumption of small fruits have been established. Washing blackberries did not significantly reduce Cu or Cd concentrations but did reduce lead concentrations; however, Pb below maximum guideline limits even before washing. An 80g portion of blackberries was considered suitable for human consumption, but a larger (e.g., 1 kg) portion would be unsafe. These findings are not representative of all foraged material or roads, so future research should consider: (1) road type, condition, and traffic volume, (2) proximity of sample sites to roads, (3) other local sources of contamination, and (4) other metal/metalloid road traffic pollutants.