Why are some molecules more poisonous than others?
There is no definite factor in determining why some molecules are more poisonous than others. As discussed, the method of absorption will affect the poisons ability to enter the bloodstream so that it may cause illness or death. The more effective the method and the rate of absorption, the more cells may be harmed, and therefore the more poisonous a molecule is. The research showed that if the xenobiotic was inhaled, then the chemical got into the blood faster however the large surface area of the ileum also allows for effective absorption. Secondly, the dosage is a crucial factor in determining how much damage and therefore how poisonous a molecule is. The lower the NOEL and LD50 of a molecule, the more harmful each molecule are, therefore the toxicity of a molecule increases as the dose required to do damage decreases. The dosage itself is dependent upon the molecule and its molecular structure. If the molecule is a highly reactive species, lipid or water soluble, absorbed through inhalation or indigestion and is relatively stable, then the molecule will be more poisonous than molecules without these characteristics. Finally, the amount of exposure to the body has to the poison over a period or in quantity/ dosage is a major factor in its toxicity.