Another mining dam collapsed in Brazil last month, bringing the country's total of these human and environmental disasters to more than 80. With at least 600 mining dams still operating, the government urgently needs to evaluate the associated risks, tighten its mining code and enforce its safety law for dams.

The environmental effects reach beyond the pollution of fresh water, soils and coastal systems. Such accidents eradicate rare endemic species and disrupt ecological interactions, ecosystem functions and evolutionary processes (M. Lambertz and J. A. Dergam Nature 528, 39; 2015; J. Massante Nature 528, 39; 2015).

Those responsible for these dam accidents still go unpunished (R. Meira et al. Biodivers. Conserv. 25, 407–409; 2016). In our view, the most pervasive and systematic threats to Brazil's biodiversity are rooted in weak official policies and poor monitoring, management and legislation.

Three mining companies in Brazil have set up a US$1.1-billion foundation to mitigate social, environmental and economic effects on the Rio Doce basin. But without policy reform, the ecological and social issues could dash Brazil's hopes of meeting the 2020 Aichi biodiversity targets (M. Di Marco et al. Conserv. Biol. 30, 189–195; 2016).