Every product in existence is assigned an LD50 number. This number is abbreviated for "Lethal Dose 50"- the quantity of chemical that is required to kill half the population of mice in a lab. Basically, the lower the number, the more toxic the substance. The greater the number, the less toxic the substance because it takes more to kill the same number of mice. Everything from water to Dawn dish detergent has an LD50. Above is a list of examples- some of these might surprise you! Round up, aka glyphosate, is getting a lot of attention recently. You can see it isn't very toxic at all compared to Vitamin D!
Clicking on the image should allow you to enlarge it and make it much more clear.