Wastewater from coking is highly toxic and carcinogenic. Reports regarding the levels of toxic chemicals were inconsistent. The sclera is highly resistant to injury from brief exposure to toxic chemicals. The derivative forms "toxic" and "poisonous" are synonymous. Discharge of toxic substances has been sharply reduced. It is a corrosive and highly toxic gas. Examples of highly toxic herbs include poison hemlock and nightshade. Most animals have excretory systems for elimination of soluble toxic wastes. Bacteria are also used for the bioremediation of industrial toxic wastes. They also require the disposal of large amounts of toxic waste. Fears of honey contamination with toxic oleander nectar are therefore unsubstantiated. There are many ways to make relative comparisons between toxic substances. There are reports of illegal dumping of toxic waste. This results in the buildup of dietary phenylalanine to potentially toxic levels. A search for toxic substances did not occur.