Areas of toxicology specialization can be categorized in various ways. One classification scheme often used relies on job setting or type of issue the toxicologist is likely to be working on. For example, toxicologists working in a clinical setting or a forensic laboratory determine what caused a toxic reaction in a person. Some may specialize, say, in venomous animals and poisonous plants. Professionals focusing on workplace exposure might call themselves occupational toxicologists. Determining how much of a drug or other chemical (e.g. a pesticide or cosmetic ingredient) should be considered safe as it is being developed by a company, and before used by consumers, is a challenge faced by industry toxicologists. Establishing safe levels after production and use of a chemical so that the public continues to be protected from harmful levels is one of the main roles filled by regulatory toxicologists and others working outside of a government setting on similar issues related to risk assessment. The study of harmful effects on plant and animal wildlife in our immediate environment and larger ecosystems is a subspecialty called ecotoxicology or environmental’ toxicology. Another way to categorize areas of toxicological specialization is analogous to medical specialties. Like physicians, toxicologists may focus on, say, reproduction and development, the lung, or the kidneys. Others focus more at the molecular level and may refer to themselves as mechanistic toxicologists.