Abnormal chromosomes. Light micrograph of abnormal chromosomes (purple) from a hamster. This hamster has 88 chromosomes instead of the normal 44. This is known as diploidism. The defect could have been caused by a toxin or a cancer-causing chemical. Chromosomes are the structures inside cells that form from the genetic material (DNA) during cell division. Photographed in the Health and Pollutants Laboratory of the INRS (the French National Institute of Research and Safety), Nancy, France. Tests are carried out here to establish the toxicity and cancer-causing properties of different materials, chemicals and pollutants.