Honeybees and their products as potential bioindicators of heavy metals contamination

The concentrations of three representative heavy metals (cadmium, chromium and lead) were measured by atomic absorption spectroscopy in honeybees and in apiary's products (honey, pollen, propolis, and wax). Samples were collected from five different sampling points: four from areas surrounding the city of Rome, and the fifth in the city center which receives intense vehicular traffic. All apiaries employed for this study were specifically constructed without any metal part in order to avoid the risk of contamination of the assayed materials. Sample collection was conducted over a 3-month period (6 samplings for honey and pollen, 3 sampling for propolis and wax, 2 samplings for honeybees, all of which were collected in duplicate). Experimental data revealed, in general, statistically significant differences between the background levels of heavy metals recorded from the reference sites and the levels measured in the site located in the center of the city of Rome. These results indicate that honeybees and, to a lesser extent, some of their products (pollen, propolis, wax, but not honey), can be considered representative bioindicators of environmental pollution.