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Why did manufacturers remove mercury from modern alkaline batteries?

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Cross-section diagram of an alkaline-manganese dioxide battery showing labeled internal components, including the steel-plated covers, cathode, anode gel, current collector, separator, steel can, and brass rivet. — battery Cutaway view of an alkaline–manganese dioxide power cell.

Manufacturers removed mercury from modern alkaline batteries primarily to reduce the environmental impact of their disposal.1

In early alkaline battery designs, the zinc anode contained 6 to 8 percent mercury. However, because mercury is a toxic heavy metal that can cause severe health issues—such as mercury poisoning—its presence in consumer goods poses significant risks to human health and ecosystems if released into the environment through waste streams. By eliminating added mercury, manufacturers have made these common household batteries safer for the public and the planet.12