In a study published in the journal Ambio, scientists found that lead levels in soil in the North-eastern United States had decreased markedly since the introduction of unleaded gasoline.

在人类环境杂志（Ambio）上发表的一项研究称，科学家们发现，自从使用无铅汽油以来，美国东北部土壤中的铅含量已经显著下降。