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Honey: A biomarker for pollution

Areas with heavy vehicle movement and industrial activity had increased concentration of lead in honey compared to agriculture land

Honey: A biomarker for pollution

Honey from urban areas can be used as a biomarker to identify polluted localities, according to a study conducted by the Pacific Centre for Isotopic and Geochemical research (PCIGR). The study was conducted in Vancouver, Canada, and has been published in the journal Nature Sustainability, on March 12, 2019.

The honey samples, analysed for the study, were collected from six geographical areas within Vancouver, including urban, industrial, residential and agricultural. From these samples, the scientists tested for three major elements — Lead, Zinc, Copper.

The results showed that areas with heavy vehicle movement and industrial activity had increased concentration of lead in honey. On the other hand, samples from agricultural land indicated high levels of manganese, which researchers suspect could be because of pesticide use.

The trace elements levels in honey is well below the worldwide average for heavy metals, says the study. This means that an adult would have to consume more than 600 grams, or two cups, of honey every day to exceed tolerable levels.

"The good news is that the chemical composition of honey in Vancouver reflects its environment and is extremely clean. We also found that the concentration of elements increased the closer you got to downtown Vancouver, and by fingerprinting the lead we can tell it largely comes from human-made sources," Kate E. Smith, lead author of the study and PhD candidate at PCIGR, was quoted as saying in media reports.

In order to make sure that the high lead concentrations are from pollutants, the researchers compared the lead sample from honey to the local, naturally occurring lead samples — and the results did not match.

Since the honey bee collects nectar from within a range of three to four kilometers, it is easy to point the source for its contamination. The researchers plan further honey analysis to see if it can complement traditional air and soil monitoring techniques, and test the efficiency of honey as an environment monitor in other cities as well.

Similarly, another study of the aquatic plant called water hyacinth, or Eichhornia crassipes, found that these can be used as biomarkers. This plant is commonly found in tropical countries and is known for its ability to absorb nutrients and other elements from water.

The stems and leaves have been successfully used as indicators of heavy metal pollution in tropical countries. The uptake of heavy metals in this plant is stronger in the roots than in the floating shoots, states the study.

(The author is a Reporter at Down To Earth, covering stories related to food, nutrition, and health. The views expressed are strictly personal)

Meenakshi Sushma

Meenakshi Sushma

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