Plant defense against herbivory which differ from one another in both functional groups, and in basic carbon skeletons. Monoterpenoids, continuing 2 isoprene units, are volatile essential oils such as citronella, limonene, menthol, camphor, and pinene. Diterpenoids, 4 isoprene units, are widely distributed in latex and resins, and can be quite toxic. Diterpenes are responsible for making "Rhododendron" leaves poisonous. Plant steroids and sterols are also produced from terpenoid precursors, including vitamin D, glycosides (such as digitalis) and saponins (which lyse red blood cells of herbivores). Phenolics, sometimes called "phenols", consist of an aromatic 6-carbon ring bonded to a hydroxy group. Some phenols have antiseptic
Drug pollution Drug pollution Drug pollution or pharmaceutical pollution is pollution of the environment with pharmaceutical drugs and their metabolites, which reach the aquatic environment (groundwater, rivers, lakes, and oceans) through wastewater. Drug pollution is therefore mainly a form of water pollution. "Pharmaceutical pollution is now detected in waters throughout the world," said a scientist at the Cary Institute of Ecosystem Studies in Millbrook, New York. "Causes include aging infrastructure, sewage overflows and agricultural runoff. Even when wastewater makes it to sewage treatment facilities, they aren't equipped to remove pharmaceuticals." Most such pollution comes simply from the drugs having been cleared and