Salt
The amount of iodine and the specific iodine compound added to salt varies from country to country. In the United States, the Food and Drug Administration (FDA) recommends [21 CFR 101.9 (c)(8)(iv)] 150 micrograms of iodine per day for both men and women. US iodized salt contains 46–77 ppm (parts per million), whereas in the UK the iodine content of iodized salt is recommended to be 10–22 ppm.
Xylidine
The U.S. Occupational Safety and Health Administration (OSHA) has set the legal limit (Permissible exposure limit) for xylidine exposure in the workplace as 5 ppm (25 mg/m) skin exposure over an eight-hour workday. The U.S. National Institute for Occupational Safety and Health (NIOSH) has set a Recommended exposure limit (REL) of 2 ppm (10 mg/m) skin exposure over an eight-hour workday. At levels of 50 ppm, xylidine is immediately dangerous to life and health.