Research led by environmental health sciences (ENHS) associate professor Eric Vejerano has found that leaves are a source of biogenic persistent free radicals (BPFRs).
With funding from the National Science Foundation, Vejerano and Ph.D. in ENHS alumna
Jeonghyeon Ahn published their findings in Environmental Science & Technology Letters.
“We found that both coniferous and broadleaf plants contained substantial levels of
persistent free radicals,” he says. “This suggests that the vast amount and perpetual
supply of leaf litter is an unaccounted source of persistent free radicals that, if
toxic, may have negative health impacts when inhaled or ingested.”
As an atmospheric/air quality scientist, Vejerano’s work focuses on environmental
pollutants, particularly those with the potential to be airborne. He specializes in
studying and tracking environmentally persistent free radicals (EPFRs) – a class of
pollutants that can remain in the environment for hours or even months, sometimes
traveling long distances and capable of causing adverse impacts to human and environmental
With this latest study, leaf litter can be added to the list of BPFRs.
Though EPFRs and their environmental/health risks have been studied extensively in
the decades since they were discovered in 1954, most research has focused on those
resulting from combustion and thermal processes. With this study, Vejerano and his
team turned their attention to naturally-occurring materials, looking to see whether
BPFRs can develop and stabilize in leaves.
In addition to looking at different types of plants, they also assessed the presence
of BPFRs in live and decaying leaves as well as their persistence through multiple
wet and dry cycles. The BPFR levels not only persisted but increased throughout the
“With 82 percent of the Earth’s land biomass comprised of plants, the presence of
BPFRs in leaf litter has significant implications,” Vejerano says. “When contained
in leaves, BPFRs pose no health threats. However, when leaf litter eventually disintegrates,
BPFRs can be absorbed into and then dispersed, where they can create potential hazards
for human and environmental health.”
The National Science Foundation supported this work through grants 1738337 (EPSCOR
RII-Track IV), 1834638 (CBET), and 214282 (CAREER).