Honey bees are increasingly being kept in or near cities, where traces of metals from industry and traffic contribute to the overall pollution. Since worker bees cover a comparatively wide area around their hive while collecting nectar and pollen, they could potentially be used to monitor and track such trace elements.

Mark Patrick Taylor, Macquarie University, Sydney, Australia, and colleagues have analyzed concentrations of As, Mn, Pb, and Zn in honey bees, wax, and honey from different sites in the area around Sydney and from the mining city of Broken Hill, both in Australia. The team sampled ten beehives in the most intensive foraging period between spring and late summer. They collected both worker bees, which travel long distances, and drones, which stay in or near the hive, as well as raw honey and wax. To find the sources of the trace elements, the team also collected dust and soil samples.

The samples were analyzed using an inductively coupled plasma mass spectrometer (ICP-MS). The researchers found slightly higher concentrations of trace metals in worker bees compared with drones. The difference can be attributed to exposure to pollutants during foraging. The team found a strong correlation between the environmental concentration of lead and the contamination of bees, wax, and honey. The heavy metal accumulates in the bees over time. The concentrations of the other tested metals were not as strongly correlated with the amounts found in bees and their products.

The isotopic ratios of ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁷Pb showed that in the mining town, the lead stemmed from the local ores, while in metropolitan Sydney, the isotope ratio was similar to that measured for aerosols from leaded petrol. Since leaded petrol has been phased out almost completely, this demonstrates that previously emitted lead is still circulating and can contaminate ecosystems and food.

• Identifying Sources of Environmental Contamination in European Honey Bees (Apis mellifera) Using Trace Elements and Lead Isotopic Compositions,
  Xiaoteng Zhou, Mark Patrick Taylor, Peter J. Davies, Shiva Prasad,
  Environ. Sci. Technol. 2018.
  https://doi.org/10.1021/acs.est.7b04084