How many people were exposed to PBB as a result of the incident?

• A. 9 million
• B. 1 million
• C. 100 thousand
• D. 5 million

Answer: (A)

The main idea here is the scale of exposure when a contaminant enters a widely distributed food supply. In the PBB incident, polybrominated biphenyls were accidentally added to cattle feed. That contamination moved through the dairy and meat supply, so products from many farms reached consumers across a large area. Because dairy products and meat can come from a huge number of households, the potential exposure encompassed a very large population. Public health investigations estimate that about 9 million people could have been exposed through consumption of contaminated dairy and animal products during the incident. That large number reflects the broad reach of the contaminated food supply, which is why it’s the best fit among the options. The smaller figures don’t capture the extensive distribution of affected products, so they don’t align with the real-world reach of the contamination.