The underlying factor linking diet and prostate cancer is probably hormonal. Fats stimulate increased production of testosterone and other hormones, and testosterone acts to speed the growth of prostate cancer. High testosterone levels may stimulate dormant prostate cancer cells into activity. Some findings suggest that high testosterone levels also influence the initial onset of prostate cancer. Eating meat may be risky for other reasons, such as meat cooked at high temperatures produces cancer-causing substances that directly affect the prostate. Other risk factors have been noted. Welders, battery manufacturers, rubber workers, and workers frequently exposed to the metal cadmium seem to be abnormally vulnerable to prostate cancer.