Cities’ environment vs urban farming: How safe is it to eat food grown there?

Valeria Vlasova
25.11.2021
5 min read

Urban agriculture has many benefits – it reduces transportation costs, improves community development, supports local food producers, offers people healthy activity, and has a potential to increase food security resilience. Besides that, it is also noteworthy to look closely at the environmental risks and benefits that relate to agricultural production in urban settings.

Great examples of urban agriculture highlight specific issues about environmental health risks of urban farming. Although one of the major co-benefits of urban agriculture lies in its contribution to the urban environment, green infrastructure and the related ecosystem services, there are worries about cities’ soil safety, air and water pollution – basic elements of agriculture – and their impact on urban food production and, hence, public health.

Soil

Healthy soil is vital for crops and is characterized by abundant soil nutrients (nitrogen, phosphorus, potassium, and calcium), physical properties like adequate water absorption or drainage, and a neutral pH to allow optimal nutrient absorption. Urban environment, however, has many potential sources of soil contamination like heavy metals, PAH’s and PCB’s from former industrial or commercial lands; past or present pesticide use or misuse; waste disposal and other human activities; and many more (1).

Although soil contamination is widespread in urban environments, not all of these pollutants will spread into food. For example, lead pollution – common in many urban areas, but can be diluted by adding compost that nourishes the soil – has very little impact on the edibility of fruiting vegetables (tomato, pepper, eggplant, etc.), but it does reduce the edibility of some vegetables like leafy vegetables (lettuce, cabbage, spinach, etc.) and root vegetables (carrot, radish, beetroot, etc.) (2). Luckily, there are many soilless systems examples that are gaining popularity around the world and are perfect for urban agriculture and safe for people's health. 

Air

As in the case of soil contamination, not all crop types are equally sensitive to air pollution (2). Of course, deposition of industrial and traffic-related air pollutants are not good for any food-growing practices, but locating gardens away from heavy traffic and industrial sites is a safe option both for crops and for people who then consume it (1).

Another fact that could embrace urban farming is its great impact on air quality in urban areas. Only 1 square meters of agricultural rooftop space in a city can offset the annual carbon emissions of one car (3)!

Water

Clean water irrigation is not only an important condition for a good crop production but also one of the key factors in preventing soil contamination. Unfortunately, water can also be a source of bacteriological pollution from residents’ wastewater or phytosanitary pollution from the use of harmful pesticides (2). The use of potable water can also be problematic due to the high demand placed on water systems during the growing season and climate-driven water shortages (1).

Rainwater collected in rain barrels is a popular alternative to potable water and is safe for irrigating most non-edible gardens and can be used in the production of food crops if certain precautionary measures are taken. Rainwater safety depends heavily on how it was collected and stored, so when barrels are kept in clean and safe condition to eliminate pathogens or mosquito larvae it reduces the risk of pollution too (1). Nevertheless, don’t forget to always wash any production collected in the urban garden with clean potable water before consumption.

Ecosystem & biodiversity

Team of researchers from the GeoSyntheSES lab at Penn State University found out that urbanization and biodiversity are not really contradictory (4). On the contrary, urban agriculture with it’s wide variety of approaches supports food and nutritional biodiversity, and growing food in urban areas has been shown to boost the abundance and diversity of wildlife, as well as protect their habitats. For example, one of the recent studies found that community gardens and allotments act as hotspots for pollinating insects, because they tend to contain a diverse range of fruiting and native plants (5). 

The bottom line

It’s expected that in 2050 about 50% of all people on earth are living in cities and will need clean water, food, energy, social space, relaxation areas and knowledge pools (6). Urban agriculture in this case demands efforts both to improve understanding of the risks and to improve present practices. With adoption of sustainable farming practices in urban areas the potential of urban agriculture is enormous.