“…Unfortunately, the exposure concentrations at which these effects were seen in workers are not known. Because Raynaud's disease was usually detected before acroosteolysis in vinyl-chloride workers, vascular lesion is believed to precede the bone changes (Dodson and Dinman, 1971). Viola (1970) reported that an exposure of rats at 30,000 ppm for 4 h/d, 5 d/w for 1 y resulted in pathology in the paws, such as metaplasia of metatarsal bones, chondroid metaplasia, epidermal edema, epidermal hyperkeratosis, and degeneration of basal cells.…”