The dam failure that killed at least two people and left many more missing in Brazil turned the spotlight back on the issue of safety and health in the mining industry.

A report by The Wall Street Journal found that the accident at the mine operated by Samarco, jointly owned by BHP Billiton and Vale, comes at time that has seen a stall in safety improvements at large mining companies.

The Wall Street Journal notes that the mining industry has made vast improvements in safety during the past decade, but it also points out that fatalities at some of the largest mining companies in the world have seen an increase in the past year. BHP recorded five fatalities in its financial year through June, at operations in Australia, Chile and South Africa, up from none in the prior 12 months.

In a press conference in Melbourne, BHP Chief Executive Andrew Mackenzie spoke about the dam failure in Brazil and said: “My sole focus is very much on making people safe and thinking about how we can clean up the impact of this incident.”

BHP’s Anglo-Australian peer, Rio Tinto, reported three deaths in the first eight months of 2015, compared with two in all of 2014. In the first half of 2015, Anglo American PLC, a U.K.-listed mining company with substantial operations in South Africa, suffered five deaths, compared with a total of six in 2014, while Glencore PLC, another large mining company, recorded eight worker deaths, compared with 16 in all of 2014.

The small rise in fatalities has occurred despite industry efforts to reduce employee deaths in recent years.

Large, highly mechanized mines and reduced workforces have aided a steady fall in accident-frequency rates. Companies have been willing to share knowledge on safety matters, establishing global standards. Companies have also made ensuring safety a crucial measure in calculating executive bonuses.

Two years ago, BHP said it would close its Perseverance underground operation, in Western Australia state, over safety concerns.

“Twenty years ago, safety was not the priority within Rio Tinto—indeed the whole resources sector—that it is now,” he said. “Now we start each meeting with a safety share, we de-risk the workplace, we measure, and we continuously translate mistakes into learnings to make people safer.”

Still, there is a danger mining companies’ recent success might have bred some complacency, warned David Cliff, professor of occupational health and safety in mining at the University of Queensland in Australia, in a recent paper.

The pressure on mines to improve productivity and cut staffing could “lead to a reversal of the safety culture improvement through the focus on doing what has to be done rather than what should be done,” Cliff wrote. “There is a real danger that the health and safety performance in developed countries will get worse rather than better.”

China continues to be beset by fatal mining accidents. Even so, the number of annual deaths related to coal mining fell under 1,000 last year, according to government data cited by Professor Tim Wright of the University of Sheffield in the U.K. As recently as 2002, nearly 7,000 coal miners died in a single year.

In the U.S., fatal mining accidents rose to 45 last year, up from 42 in 2013, according to the U.S. Labor Department’s Mine Safety and Health Administration. This year, fatal incidents are tracking behind those levels, with 25 deaths recorded as of Nov. 6.