Natural Lead Levels in Dandelions (Taraxacum officinale): A Weed, Folk Medicine, and Biomonitor

Abstract

The natural lead concentration of dandelion (Taraxacum officinale) leaves is estimated to be 0.2 μg/g (dry weight), or 1–3 orders of magnitude below most contemporary measurements of that value for dandelions and other plants. This estimate is based on analyses of lead concentrations of dandelions grown in a trace metal clean laboratory, with environmental lead concentrations approximating natural levels. The protocols used in this study paralleled those in our previous study that estimated the natural blood lead level in humans (0.016 μg/dL), which is also 1–3 orders of magnitude below most contemporary measurements. Analyses of the isotopic ratios (206Pb/207Pb:208Pb/207Pb) of the lead in the plants grown in the laboratory and greenhouse and those collected in the field, as well as the isotopic ratios of the soils the plants were grown in in the laboratory, indicate that anthropogenic lead makes up a substantial amount of labile lead in today’s environments. Consequently, this estimate of the natural lead level in dandelion leaves provides both a benchmark for comparison of lead concentrations in contemporary plants and yet another measure of persistent lead contamination in the biosphere.

Metastable Zirconium Phosphate under Nanoconfinement with Superior Adsorption Capability for Water Treatment

“…It is of extreme practical importance to examine the selective adsorption of our sample toward heavy metal cations with the presence of much higher concentrations (10 1 –10 3 times) of competing mineral cations, e.g., Ca II , in real contaminated water 28. Results in Figure a–c shows that Ca II ions strongly compete with heavy metal ions, i.e., Pb II , Cd II , and Ni II , for the adsorption sites of α‐ZrP and commercial cation exchange resin D001, which is a macroporous polystyrene functionalized with sulfonic groups.…”

Distinguishing between Natural and Industrial Lead in Consumer Products and Other Environmental Matrices

“…The dandelions were grown in trace metal clean conditions in HEPA-filtered air (Class 1000) trace metal containers of acid-cleaned plastic, with high-purity (18.2 MΩ cm) water and either low-lead commercial soil or cleaned beach sand with a commercial fertilizer. 42 Control samples were concurrently grown in the greenhouse of the university, where the containers and substrate were the same as those in the clean lab cultivations but the air was ambient and the water was municipal. In addition, we collected and measured dandelion and soil lead concentrations in Santa Cruz, which is a small coastal community with little industry, and at Stanford's Jasper Ridge Biological Reserve, which is a relatively pristine area in the Santa Cruz Mountains south of San Francisco (https:// jrbp.stanford.edu).…”

“…period, using quarterly 6 day duplicate samplings. Other lead isotopic composition measurements include the preceding studies of lead contamination in dandelions 42 and chocolate. 63 There have also been reports on lead isotopic compositions of fruits and vegetables, 72−74 cane and sugar beets, 75 maize, 76 wheat, 77,78 rice, 79 honey, 31,80 finfish, 81 shellfish, 82−88 tea, 89 cocoa, 90 vinegar, 91 and alcoholic beverages other than wine.…”

“…The dandelions were grown in trace metal clean conditions in HEPA-filtered air (Class 1000) trace metal containers of acid-cleaned plastic, with high-purity (18.2 MΩ cm) water and either low-lead commercial soil or cleaned beach sand with a commercial fertilizer . Control samples were concurrently grown in the greenhouse of the university, where the containers and substrate were the same as those in the clean lab cultivations but the air was ambient and the water was municipal.…”

“…The most extensive of those studies was by Gulson et al, who tracked the lead isotopic composition of the diets of a small cohort of Australians over a 10 year period, using quarterly 6 day duplicate samplings. Other lead isotopic composition measurements include the preceding studies of lead contamination in dandelions and chocolate . There have also been reports on lead isotopic compositions of fruits and vegetables, − cane and sugar beets, maize, wheat, , rice, honey, , finfish, shellfish, − tea, cocoa, vinegar, and alcoholic beverages other than wine .…”