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sensitization

生体は、自然にせよ人工的にせよ体内に抗原が入ると、それに対する免疫応答の結果として特異的に反応する抗体およびリンパ球を生じ、ふたたび抗原と遭遇するとアレルギー反応をおこす。このように、ある抗原に対しアレルギー反応をおこしうる状態にすることを感作という。たとえば、モルモットに異種タンパク(抗原)を注射し、1~2週間後にふたたび同じ抗原を注射するとアナフィラキシー(激しいショック症状)をおこすが、この場合、前処置注射を「感作する」という。
 感作と免疫は区別せず使われることも少なくないが、一般的には、アレルギーをおこしやすい状態にする場合には、「免疫する」というよりも「感作する」ということばが使われる。すでに感作された生体から抗体や感作リンパ球をとり、これを未感作生体に移入することにより感作を成立させることもできる。これを受け身感作(受動感作)という。また、感作という用語は、特異的抗体を結合させた赤血球に対しても用いられ、感作赤血球とよばれる。これは補体結合反応や凝集反応に使用される。さらには、抗原を非特異的な方法で結合させた赤血球も、感作赤血球とよばれることがあり、これは抗原特異的抗体に対する凝集反応などに使用される。

魚類急性毒性試験(OECD TG203)
水系食物連鎖における高次消費者である魚類を化学物質に96時間暴露させ、死亡数を計測し半数致死濃度LC50(lethal concentration 50)を求める。供試動物としては日本においてはヒメダカ、コイが一般的であるが、海外においてはブルーギルニジマスグッピーなどが用いられる。

A biocide is defined in the European legislation as a chemical substance or microorganism intended to destroy, deter, render harmless, or exert a controlling effect on any harmful organism by chemical or biological means. The US Environmental Protection Agency (EPA) uses a slightly different definition for biocides as "a diverse group of poisonous substances including preservatives, insecticides, disinfectants, and pesticides used for the control of organisms that are harmful to human or animal health or that cause damage to natural or manufactured products". When compared, the two definitions roughly imply the same, although the US EPA definition includes plant protection products and some veterinary medicines.

The terms "biocides" and "pesticides" are regularly interchanged, and often confused with "plant protection products". To clarify this, pesticides include both biocides and plant protection products, where the former regards substances for non-food and feed purposes and the latter regards substances for food and feed purposes.

When discussing biocides a distinction should be made between the biocidal active substance and the biocidal product. The biocidal active substances are mostly chemical compounds, but can also be microorganisms (e.g. bacteria). Biocidal products contain one or more biocidal active substances and may contain other non-active co-formulants that ensure the effectiveness as well as the desired pH, viscosity, colour, odour, etc. of the final product. Biocidal products are available on the market for use by professional and/or non-professional consumers.

Although most of the biocidal active substances have a relative high toxicity, there are also examples of active substances with low toxicity, such as CO2, which exhibit their biocidal activity only under certain specific conditions such as in closed systems. In such cases, the biocidal product is the combination of the active substance and the device that ensures the intended biocidal activity, i.e. suffocation of rodents by CO2 in a closed system trap. Another example of biocidal products available to consumers are products impregnated with biocides (also called treated articles), such as clothes and wristbands impregnated with insecticides, socks impregnated with antibacterial substances etc.

Biocides are commonly used in medicine, agriculture, forestry, and industry. Biocidal substances and products are also employed as anti-fouling agents or disinfectants under other circumstances: chlorine, for example, is used as a short-life biocide in industrial water treatment but as a disinfectant in swimming pools. Many biocides are synthetic, but there are naturally occurring biocides classified as natural biocides, derived from, e.g., bacteria and plants.[1]

A biocide can be:

A pesticide: this includes fungicides, herbicides, insecticides, algicides, molluscicides, miticides and rodenticides.
An antimicrobial: this includes germicides, antibiotics, antibacterials, antivirals, antifungals, antiprotozoals and antiparasites. See also spermicide.