Hunting down hidden health benefits and dangers of urban fruit

http://www.eurekalert.org/pub_releases/2015-11/gsoa-hdh110115.php

Public Release: 1-Nov-2015
Hunting down hidden dangers and health benefits of urban fruit
Geological Society of America

Forgotten trees from long lost orchards and 20th-century city landscaping are being rediscovered in urban areas, and their fruits are proving not only largely free of urban pollutants, but more nutritious than their retail counterparts.

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"This is a story with a good ending: not much lead in these urban harvested fruit," said Wellesley geosciences and environmental studies professor Dan Brabander, who has previously studied lead exposure risk in urban gardens and in areas impacted by historical mining activities.

The LUrC study investigated the concentrations of lead in urban fruits when they were peeled and unpeeled as well as washed and unwashed. That was intended to distinguish whether the fruits were taking up lead internally or being contaminated by dry deposition from the air or from soil dust.

"We found there was no difference between these variables," said Ciaran Gallagher, an undergraduate researcher majoring in Environmental Chemistry at Wellesley College,

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The researchers also looked at arsenic in the fruits, because in older orchards farmers commonly used lead arsenate as a pesticide. "So we are keeping an eye on places where this pesticide might have been historically applied." To date the researchers have not found evidence of use in the LUrC samples.

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In addition to lead and arsenic, they also looked into the nutritional value of urban fruit. They compared micronutrient levels with those in commercially grown fruits and found that calcium concentrations in urban apples and peaches are more than 2.5 times those in their commercial counterparts. Concentrations of calcium and iron were higher in urban fruits for every fruit type tested, and manganese, zinc, magnesium, and potassium concentrations were higher in certain urban fruit types. On average, urban fruit contains a wider range of micronutrients than its commercial counterparts.

"When they grow in a commercial setting the soils can become quite impoverished," Brabander explained. "In the urban setting where the trees sampled tend to be older perhaps they are able to shuttle micronutrients from a wider and more diverse range of horizons." Planned future soil coring work into urban soils will try to figure out the mechanism of nutrient transfer in this unique setting.

"That's not to say that all urban produce is safe to eat, however, because local conditions vary and antique fruit trees are found in some very unexpected -- and sometimes very polluted places, like along major roadways," said Brabander.

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