Question

A study in the 1990s found that residents of Mexico City had higher levels of lead and cadmium in their blood than did residents of any other urban area in the world. What is the most likely explanantion for this?
A. water pollution
B. heredity
C. air pollution
D. diet

Answer 1

The most likely explanation for the higher levels of lead and cadmium in the blood of residents of Mexico City compared to other urban areas is **C. air pollution**. Mexico City has historically struggled with significant levels of air pollution due to industrial emissions, vehicle exhaust, and other environmental factors, which can contribute to increased exposure to heavy metals like lead and cadmium. While water pollution and diet can also play roles in exposure to these metals, the strong correlation with air pollution makes it the most plausible explanation in this context.