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The effect of the developmental toxicants depends on the type of substance, dose, duration, and time of the exposure. The first few weeks of embryogenesis in humans is more susceptible to these agents. The embryogenesis is the most crucial time for the action of any teratogenic substances to result in birth defects.
Teratogens are classified in four main categories: Drugs in pregnancy – in addition to environmental chemicals, includes recreational drug use and pharmaceutical drugs. Vertically transmitted infections; Radiation, such as X-rays; Mechanical forces, such as oligohydramnios; Teratogens affect the fetus by various mechanism including:
Occupational hazards in dentistry are occupational hazards that are specifically associated with a dental care environment. Members of the dental team, including dentists, hygienists, dental nurses and radiographers, must ensure local protocols are followed to minimize risk.
Not all select agents require BSL-4 handling, namely select bacteria and toxins, but most select agent viruses do (with the notable exception of SARS-CoV-1 which can be handled in BSL3). Many non-select agent viruses are often handled in BSL-4 according to facility SOPs or when dealing with new viruses closely related to viruses that require BSL-4.
While this is still part of the teratological evaluation procedures today, the field of Teratology is moving to a more molecular level, seeking the mechanism(s) of action by which these agents act. One example of this is the use of mammalian animal models to evaluate the molecular role of teratogens in the development of embryonic populations ...
The international pictogram for chemicals that are sensitising, mutagenic, carcinogenic or toxic to reproduction. Reproductive toxicity refers to the potential risk from a given chemical, physical or biologic agent to adversely affect both male and female fertility as well as offspring development. [1]
These agents typically include electrophilic groups that react readily with the net negative charge of DNA molecules. [20] Examples of activation-independent carcinogens include ultraviolet light, ionizing radiation and alkylating agents. [21] The time from exposure to a carcinogen to the development of cancer is known as the latency period.
Teratogens are substances that may cause birth defects via a toxic effect on an embryo or foetus. Wikimedia Commons has media related to Teratogens . See also the categories Carcinogens and Mutagens