Heavy Metal Pollution and Urban Agriculture in Msimbazi River Valley: Health Risk and Public Awareness

Awareness of the urban population on the potential environmental and human health risks resulting from and consuming vegetables polluted with heavy metals from Msimbazi river, Dar es Salaam city, Tanzania was investigated. Results show that more than 71% of the 35 respondents use Msimbazi river as a major source of water for vegetable irrigation. High levels of chromium, lead and copper have been observed in four most popular vegetables namely Amaranthus blitum, Amaranthus gangeticus, Cucurbita maxima, Ipomea batata and Brasica oleracea. The survey indicated further that about 69% of respondents are not aware on industrial pollution in the Msimbazi River. 63% of respondents do not know the potential human health effects attributed to the current irrigation practice. Vegetables grown along the Msimbazi river valley feeds most of markets in the City. The study also established the risk value as well as population at risk through oral exposure to vegetables grown in Msimbazi River valley. Results on vegetable consumption shows that 95.6% of adults, 30.7% of children aged 6-12 years and 12.5% of children aged 2-6 years are at risk of getting lead carcinogenic effects. Additionally, children aged 2-6 years (5%) followed by children aged 6-12 years (2.8%) and adults (1.2%) are at risk from carcinogenic cadmium effects. For non carcinogenic effects, 0.7% adults, 1.18% children aged 6-12 years, and 0.122% children aged 2-6 years are dermal exposed to copper in vegetables.