Ultrastructural effects of DDT on cells grown in vitro.

In vitro administration of DDT at 0.5 ppm, 10 ppm, and 50 ppm (0.5, 10 and 50 micrograms/ml culture medium) to HeLa S, human amnion (HA-FL), canine venereal tumor (CVT), canine kidney (MD-CK) and rat nephroma (RN) cells resulted in alterations of the ultrastructure of cells. Responses to the cytotoxic chemical compound were qualitatively and quantitatively similar among all mammalian cell lines tested. The tested cells exhibited dose-specific responses. Al low dose (0.5 ppm) rough endoplasmic reticulum and free ribosomes increased as did the number and size of smooth endoplasmic reticulum profiles. At higher doses (10 ppm and 50 ppm) there was indication of cellular degradation including mitochondrial disorganization, nuclear heterochromatic condensation and peripheralization, and increases in numbers of lysosomes, autophagic vacuoles and multivesicular bodies. This suggests that low level exposure to cytotoxic elements such as DDT initiates a repair and regeneration response from the cells while degenerative changes at higher exposure levels suggest less success with detoxification and possible irreversible cellular damage.