Decades ago, most of the paint used in the US was lead-based because it was cheap, long lasting, and widely available. When scientists recognized that this was polluting the air with toxic lead, laws banned lead-based paint, and the paint industry developed more cost-effective paints that do not contain lead.

Lead-based paint was banned after scientists recognized that lead pollution is toxic and can harm people’s health. The correct choice is D, health risk to users. The passage says the paint was cheap, long lasting, and widely available, so the other choices do not explain the ban.

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