How Safe Is Urban-Grown Food?

According to initial research, not only is food grown in urban environments safe, it might actually provide some nutritious advantages over food grown in other locations…

More and more, people are planting edible food into their landscapes and in parks, and foraging for edibles right in their own cities. Of course, this has led to a few concerns: could food exposed to urban pollutants promote disease in those who consume it?

A group of Wellesley College researchers together with Boston’s League of Urban Canners (LUrC) are trying to find a satisfying answer to this pressing question. Members of LUrC often go foraging for food around Boston’s urban areas, but were perturbed when they found that one of their members had tested high for levels of lead in the blood. Curious to find out why, they sought the help of Wellesley College, and specifically their professor of geoscience, Dan Brabander.

For many years now, Brabander has studied geochemisty, and the pathways by which the populace is exposed to toxic chemicals in city environments. Once the LUrC called on him with their interesting problem, his undergraduate students jumped at the chance to do some research.

Urban foraging groups normally get their supply by visiting historical areas, city parks, or even abandoned plants along the highway, sometimes in industrial locations. The LUrC specifically tends to aim their focus at the heirloom types of vegetables and fruits.

Foraging Urban Fruit

The Urban Canners sent their fruit samples off to the lab to be tested, making sure that the fruit was preserved by the same methods that they usually used, so as to not introduce any variables to skew the data. What they found was completely unexpected, considering that some media outlets had already been decrying urban edibles for heavy metal contamination in the past few years.

Surprisingly enough, though, all of their samples (166 bits of fruit, herbs, and other foraged food) showed low levels of lead and arsenic. Their apples, for instance, had levels of lead between 0.5-1.2 micrograms for every ten liters, notably less than the amount deemed safe for a child to intake in a single day (5 micrograms).

In addition, the researchers had expected to find more heavy metals in fruit that had not been peeled as opposed to fruit that had, considering that the rind would in theory be subjected to air pollution and other sources of toxicity more than the rest of the fruit. As it turned out, though, this actually made no significant difference, and the levels were similar on both peeled and unpeeled fruits.

The mechanisms by which edible plants are contaminated are still not completely understood, but it is known that some of the vegetation that is most easily subjected to arsenic and lead contamination are the tubers and root vegetables, like potatoes, with green leaf-like vegetables like spinach (has a lot of folic acid) being slightly less affected, but still susceptible. The reproductive parts of the plants, however, like the seed pods or fruit of the plant, are much less likely to be contaminated, most likely because they are the furthest away from the ground and root system.

The researchers at Wellesly warn that some types of soil are worse than others when it comes to heavy metal toxicity. They indicate that soil with low pH may be subject to lead contamination that can affect the fruit body as opposed to soil with higher pH levels. Many things can affect a soil’s susceptibility. As expected from a scientist, Brabander insists that more data is needed before any hard conclusions can be drawn; what is true for the Boston area, after all, may not be true in general for other locations.

Added Nutritional Benefits

Still, this is promising news for urban foragers, and it doesn’t stop there. The LUrC/Wellesley study also showed that apples and peaches foraged in the Boston area contained more than 2.5 times the calcium of their conventional counterparts. According to Gallagher and team, urban fruit also contains a wider range of micronutrients than the fruit available in most stores.

Calcium and iron concentrations were higher for all the fruits the group tested, and other trace minerals—including manganese, zinc, magnesium, and potassium—were also higher in some varieties. This is an important finding, as individuals who are deficient in calcium are also more susceptible to lead poisoning.

University of California Berkeley statistics Professor Philip Stark echoes the Wellesley findings. Foraged greens can add “hyper-fresh, hyper-local, hyper-nutritious greens to everyone’s diet, in particular bringing phytochemicals, micronutrients, and fiber, which the typical American diet lacks,” he says.

Stark is the lead investigator for the Berkeley Open Source Food project, where he and a group of students tested Bay Area soils for several metal contaminants as well as for nutritional composition. In all the species of foraged greens the group sent for testing, he says, “we found that even in soils with relatively high concentrations of lead (700ppm), the level of heavy metals was not a concern to eat in moderate quantities.” But Stark also advises foragers to wash all found plants well. “The dust and dirt on the leaves can have harmful levels of lead and other things,” he adds.

Professor Brabander believes this type of research can help complete a much larger puzzle. As more studies emerge, the safest ways to practice urban foraging and to plan intentional urban orchards and gardens will be more clearly defined. All this is important, adds Brabander, because, “there are so many community-level benefits from [urban foraging]—from increased food sovereignty to building community resilience!”

Corrections: This article originally stated that the scientists had tested 166 samples. In fact, they have tested 45 so far and will continue to test the remaining samples in the coming months. The maximum lead level has also been updated to reflect the newest number.


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