Today the Financial Times publishes the second part of a long investigation into the environmental and safety record of BP, one of the largest companies in the world. The investigation highlights a worrying series of accidents in the US. For oil companies, faced with the challenge of increasing profits in a world where new reserves are hard to come by, it shows that there are limits to how far costs can be cut.

In March 2005 an explosion at BP's Texas City refinery killed 15 workers; a March 2006 oil spill at BP's operations in Prudhoe Bay, Alaska, led to a complete shutdown of the field in August. But as the FT investigation reveals, doubts over BP's safety performance were being voiced long before the most recent problems.