A former chemist for W.R. Grace & Co. revealed to jurors Tuesday that in 1976, top executives ordered a “hamster study” in which the hamsters were injected with asbestos-laced vermiculite from Libby, Montana. W.R. Grace & Co. and five employees were charged with a federal conspiracy involving Clean Air Act violations and obstruction of justice. The charges relate to whether the company and its top employees knew they were endangering the community of Libby by mining asbestos-laced ore, and whether they did so in violation of federal law.

Heyman C. Duecker, who worked for Grace for more than two decades said that over time, many of the hamsters contracted mesothelioma, and eventually suffocated due to “pleural thickening,” a scarring of the lung tissue. The testing was part of a corporate directive to study the hazards of a strain of asbestos unique to Libby, and to better understand the potential health risks like mesothelioma, to miners.

In Duecker’s asbestos study, the animals were exposed to Libby vermiculite that contained various levels of a dangerous form of asbestos, called tremolite. The initial test results showed that only 1 in a group of 62 hamsters developed mesothelioma. However, five cases of mesothelioma were detected within half a year and after a year 10 cases of mesothelioma were detected among the hamsters.

Learn more about mesothelioma legal rights.