MUNICH -- Volkswagen Group, Daimler and BMW took another blow amid revelations that they sponsored tests that exposed humans as well as monkeys to diesel exhaust fumes, which can cause respiratory illness and cancer.
The study, supported by a little-known group founded by the three automakers in 2007, had 25 people breathe diesel exhaust at a clinic used by the University of Aachen, the Stuttgarter Zeitung newspaper reported Monday.
The report, citing annual reports from the European Research Group on Environment and Health in the Transport Sector, or EUGT, which closed last year, followed a report from the The New York Times earlier that said the organization also conducted tests using monkeys.
Germany's auto industry, which is still reeling from Volkswagen Group's diesel-cheating scandal where the company rigged emissions tests, distanced itself from the organization.
"We are appalled by the extent of the studies and their implementation," Daimler said Monday in an emailed statement, adding it didn't have any influence over the study and promised an investigation. "We condemn the experiments in the strongest terms."
The revelations are another bombshell undermining diesel's image. The technology remains a key profit driver for German automakers, even as demand gradually slips in Europe, the main market for the diesel models.
The reports also weaken the automakers' position in its efforts to counter criticism of the technology as cities mull bans and German politicians weigh more stringent upgrades to lower pollution levels.
In an additional twist, the VW Beetle model used in the test with animals was among the vehicles rigged to cheat on emissions tests, The New York Times reported.
Volkswagen apologized for the misconduct and lack of judgment of some individuals, calling the trials with animals a mistake. VW on Monday again distanced itself from the activities of the group.
Stephan Weil, who represents the German state of Lower Saxony, a VW shareholder, on the supervisory board, said the board was pressing the automaker to urgently provide information about what the aim of the studies was.
"At the end of the day, the purpose of such experiments is the decisive factor. If for example, safety and health in the workplace were being tested, as Aachen University has suggested, and ethical standards were adhered to, it is defensible," Weil told a news conference on Monday.
"Where experiments served the purposes of marketing and sales, however, I cannot think of an acceptable justification for such an approach."
Aachen University had no immediate comment.