Carcinogen

A carcinogen [ kartsinoge ː n] is a substance that an organism or radiation that can cause cancer or promote cancer formation.

Carcinogen called carcinogens or carcinogen and is composed of carcinoma and genesis. Better is the term carcinogen, containing the Latin word cancer and that all cancers, not just the cancer includes. Frequently the term is also used as adjectives (a substance is carcinogenic, even carcinogenic, carcinogenic or carcinogenic ). Not to be confused with the word oncogene is carcinogenic ( causes cancer ) gene.

Should it lead to the triggering of a cancer is called a cancer induction ( from the Latin: inducere, trigger, initiate ).

History

1775 was recognized by the English physician Percivall pot that among chimney sweeps through contact with soot of the so-called chimney sweeps cancer arose due to aromatic hydrocarbons in soot. At the beginning of the 19th century was reported about skin cancer among workers in copper smelting and Zinngießereien in Cornwall. Here arsenic compounds were the cause. Jonathan Hutchinson in 1888 in patients diagnosed skin cancer as a result of applications with arsenic-containing ointments. Since about 1925, arsenic compounds have been used in pesticides in vineyards and orchards. Later it was observed vintners an accumulation of typical arsenic compounds cancers, so there was a ban on these products. The surgeon Ludwig Rehn presented 1895, the increased incidence of bladder cancer among workers in aniline factories established, due to various aromatic amines. Since the start of production of PVC plastic in the 1930s occurred in workers in certain forms of liver cancer, which meant that the MAK value of vinyl chloride was repeatedly reduced drastically. Different types of cancer also occurred in workers in factories on where beryllium, cobalt and nickel compounds, chromates or asbestos are used, as well as tar and paint factories.

Basics

Carcinogens can be divided into two groups:

• Initiating carcinogens are substances that can cause cancer.
• Graduating students carcinogens, however, promote the ( further) development of cancer.

Furthermore, we speak of co- carcinogens, if a substance itself is not carcinogenic, but in certain combinations with other substances ( which also are not carcinogenic ), can cause cancer.

Many carcinogens are effective only after metabolism in the body. For example, 3,4- benzopyrene is carcinogenic only after enzymatic conversion to Epoxybenzpyren. The same applies to nitrosamines, which are metabolized into the corresponding aldehydes and reactive carbenium ions. Nitrosamines can be taken not only from the environment ( eg cigarette smoke ), but also in the stomach from nitrites and amines formed. The effect of carcinogens is mainly due to genotoxic changes in DNA and thus leads to a deterioration of the cell.

Classification of carcinogens

Natural carcinogens

Many carcinogens are found in nature. For example, aflatoxin B1, the most potent carcinogenic compounds in general, formed by the mold Aspergillus flavus. This often affects fat and starchy seeds such as nuts, grains, corn or pistachios.

Chemical carcinogens

According to § 1.4.2.1 Ordinance on Hazardous Substances Appendix 1 chemical carcinogens are divided into three risk categories. This classification corresponds to Directive 67/548/EEC and is thus a European setting. The categories mean:

Category 1

In the Category 1 substances are classified, of which the carcinogenic effect in humans is known and there is sufficient evidence to establish a causal link between the human exposure to a substance and the development of cancer. The classification and labeling is done with hazard symbol T and R45: " May cause cancer ( canc. cat 1. )" Or R49: 'May cause cancer by inhalation ( canc. cat 1. )'. (Only if they are very toxic for other reasons, they are marked with T).

Examples:

• Arsenic acid and its salts
• Asbestos
• Benzene
• Alcohol
• Dimethyl sulfate
• 2-naphthylamine
• Soluble nickel salts
• Diesel exhaust

Category 2

In the Category 2 substances are classified, which are regarded as carcinogenic to humans, so if sufficient evidence to provide a strong presumption exists that the exposure of humans to the substance can cause cancer. This assumption is based generally on long-term experiments and / or other relevant information. The classification and labeling is done with hazard symbol T and R45: " May cause cancer ( canc. cat 2. )" Or R49: 'May cause cancer by inhalation ( canc. cat 2. )'. (Only if they are very toxic for other reasons, they are marked with T). Examples:

• Acrylamide
• Benzopyrene
• Cobalt chloride
• Petrol
• Crude

Category 3

In the Category 3 substances are classified when they concern owing to possible carcinogenic effects in humans, but not enough information for a satisfactory assessment if, for example though present in appropriate animal studies evidence, but not enough to meet the material classification in Category 2. The classification and labeling is done with R40 " Limited evidence of a carcinogenic effect ." Examples:

• Chromate
• Diesel fuel / fuel oil
• Nickel ( metal)
• Ozone
• Oxazepam

Carcinogenic viruses

Tumor viruses, such as:

• HI virus
• Epstein-Barr virus
• HP viruses

Carcinogenic radiation

Electromagnetic and particle radiation can from energies of about 4 electron volts - which just corresponds to the binding energy of nucleotides in a DNA strand - be carcinogenic. Included is thus also radioactivity, as also high-energy radiation is emitted. UV -C radiation is to limit the risk and, therefore, already be carcinogenic. Visible light is not dangerous because of the small electromagnetic energy.