Metal contamination and health risk assessment for urban agriculture in Rouyn-Noranda

The Horne smelter is known for its emissions rich in several trace metal elements (TMEs). Given the recognized toxicity of certain TMEs and the growing popularity of urban agriculture, this study aims to determine the level of contamination of garden vegetables in the region and to assess potential health risks. To this end, plant (carrot, lettuce and tomato) and soil samples were collected from participating vegetable gardens (n = 20). A wide range of TMEs were measured by ICP-QQQ. In general, lettuce was the foodstuff with the highest MTE levels, probably due to its higher foliar uptake than carrots and tomatoes. Measured levels of arsenic, copper, cadmium and lead in soil or lettuce decreased exponentially with distance from the smelter, underlining its role as a major source of MTE contamination in the area. Gardens to the west of the smelter were significantly more contaminated (soil, lettuce) than those to the east, underscoring the need for a better estimate of the magnitude and impact of fugitive emissions from the smelter. The carcinogenic risk associated with eating backyard vegetables is present, but considered tolerable for certain categories of people living alone or with another person (other toxic and carcinogenic risks remain insignificant).