Bees and bee products from urban and industrial environments are far more likely to be contaminated by heavy metals:

Air and soil contain heavy metals, mainly from industry and traffic which can also contaminate the bee colony and its products. Lead (Pb) and cadmium (Cd) are considered the principle toxic heavy metals and are thus most frequently studied. Lead, contained in the air and originating mainly from motor traffic can contaminate air and then directly nectar and honeydew. On average, the Pb concentration was low and unproblematic in honey but the lead residues found in propolis are often too high and care should be taken to harvest it in areas that are at least 3 km away from motor car traffic

Apidologie 37 (2006) 1–18
Contaminants of bee products
Stefan BOGDANOV

* * *

The levels of metals in forager bodies also vary between regions and by season (Jones, 1987; Velemínský et al., 1990). For instance, the content of Pb and Cd in bee tissues from industrialized regions can be as much as ten times of those from unindustrialized areas (Hoffel, 1985). Cadmium and Pb levels were found to be significantly higher in urban areas than in nonresidential areas (Perugini et al., 2011). In semirural areas and high vehicle emission places in Brazil, Cd and Pb concentrations in pollen were much higher compared to countrysides.

Bromenshenk et al. (1985) found reduced hive productivity for colonies placed near industrialized regions where high concentrations of arsenic and Cd co-occurred. However, to our knowledge, ours is the first report detailing baseline data on honeybee forager and larval survival and development following exposure to Cd, Cu, and Pb, individually.

Chemosphere 152 (2016) 530-538
Laboratory bioassays on the impact of cadmium, copper and lead on the development and survival of honeybee (Apis mellifera L.) larvae and foragers*
John T. Trumble, & al

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html