What is benzopyrene? How is benzopyrene produced? Is benzopyrene toxic?

Benzopyrene, also known as benzo(a)pyrene, abbreviated as BaP, is a common highly active indirect carcinogen. After 3,4-benzopyrene is released into the atmosphere, it always combines with aerosols formed by various types of particles in the atmosphere. Among the inhalable dust particles below 8 microns, the rate of inhalation into the lungs is relatively high. It is inhaled into the lungs through the respiratory tract, enters the alveoli and even the blood, causing lung cancer and cardiovascular diseases.

What is Benzopyrene?

Benzopyrene (běn bìng pí) is a class of organic compounds with obvious carcinogenicity. It is a polycyclic aromatic hydrocarbon compound composed of a benzene ring and a pyrene molecule.

Of the more than 400 major carcinogens that have been detected, more than half are compounds belonging to the class of polycyclic aromatic hydrocarbons, among which benzopyrene is a strong carcinogen.

Tobacco smoke, high-temperature vegetable oils that have been used repeatedly, burnt food, and over-fried food can all produce benzopyrene.

As for benzopyrene, the Japanese have conducted experiments on rabbits. The experiments showed that after applying benzopyrene on the rabbits' ears, tumors grew on the rabbits' ears on the 40th day.

Studies have shown that for every 1% increase in benzopyrene content in the living environment, the mortality rate from lung cancer increases by 5%.

Toxicity of benzopyrene

Health hazards: Inhalation, ingestion, and skin absorption. Irritating to eyes and skin. Carcinogen, teratogen, and mutagen. Toxicity: It is the most toxic and potent carcinogen among PAHs.

Acute toxicity of benzopyrene: LD50500mg/kg (mouse intraperitoneal); 50mg/kg (rat subcutaneous)

Chronic toxicity: Long-term living in an air environment containing BaP will cause chronic poisoning. BaP in the air is one of the most important factors causing lung cancer.

Aquatic toxicity: 5μg/L, 12 days, microorganisms, inhibitory effect; 5mg/L, 13 hours, mollusk eggs, inhibitory effect, structural changes.

Benzopyrene causes cancer

BaP in cigarettes is considered a highly active carcinogen, but it is not a direct carcinogen. It must be activated by mixed function oxidase in cell microsomes to be carcinogenic. After BaP enters the body, except for a small part of it being excreted in the feces in its original form, a part of it is activated by mixed function oxidase in liver and lung cell microsomes and converted into dozens of metabolites. Among them, those converted into hydroxyl compounds or quinones are a detoxification reaction; those converted into epoxides, especially 7,8-epoxide, are an activation reaction. 7,8-epoxide is metabolized to produce 7,8-dihydrodihydroxy-9,10-epoxide benzo[a]pyrene (as shown in the figure), which may be the final carcinogen. This final carcinogen has four isomers, among which (+)-BP-7β,8α-diol-9α,10α-epoxide-benzo[a]pyrene has been proven to be the most carcinogenic. It forms a covalent bond with DNA, causing DNA damage. If DNA cannot be repaired or is repaired without recovery, cells may become cancerous. The other three isomers also have carcinogenic effects. Animal tests, including oral, percutaneous, inhalation, and intraperitoneal subcutaneous injection, all showed carcinogenicity. Many countries have successively conducted experiments on 9 kinds of animals, using a variety of administration routes, and the results have all obtained positive reports of inducing cancer. Among PAHs, BaP is the most widely polluted and the most carcinogenic. BaP is not only widely present in the environment, but also relatively stable, and has a certain correlation with the content of other PAHs. Therefore, BaP is generally regarded as a representative of atmospheric carcinogens.

Benzopyrene teratogenicity

1000mg/kg, oral administration to pregnant rats, caused fetal teratogenesis.

Benzopyrene causes DNA mutation

40mg/kg, once, voles, intraperitoneal administration, chromosome test, multiple changes. Mice, genetic phenotype test, multiple changes. Insects, genetic phenotype test, multiple changes. Microorganisms, genetic phenotype test, multiple changes. Human cell culture DNA, multiple changes.

Sources of benzopyrene pollution

It exists in coal tar, various types of carbon black, smoke from the combustion of coal and petroleum, cigarette smoke, automobile exhaust, and industrial wastewater from coking, oil refining, asphalt, plastics, etc. In addition to industrial sewage, BaP in surface water mainly comes from rainwater washing the atmosphere. Leaching of water storage tanks and pipeline coatings.

First aid treatment for benzopyrene

1. Emergency treatment of leakage

Isolate the leaked contaminated area, set up warning signs around it, and have emergency personnel wear self-contained breathing apparatus and chemical protective clothing. Do not directly contact the leaked material, avoid raising dust, sweep it up carefully, solidify it with cement, asphalt or appropriate thermoplastic materials before discarding it. If there is a large amount of leakage, collect and recycle it or treat it harmlessly before discarding it.

2. Protective measures

Respiratory protection: Generally no special protection is required, but it is recommended to wear a self-contained breathing apparatus in special circumstances.

Eye protection: Wear safety glasses.

Protective clothing: Wear polyethylene film anti-toxic clothing.

Hand protection: Wear chemical-resistant gloves when necessary.

Others: After work, take a shower and change clothes. Avoid long-term and repeated contact. Beware of its carcinogenicity.

3. First aid measures

Skin contact: Take off contaminated clothes and rinse thoroughly with soap and water.

Eye contact: Immediately open the upper and lower eyelids and rinse with running water for 15 minutes. Seek medical attention.

Inhalation: Get out of the polluted environment, rinse the nasopharynx with water to remove dust. Seek medical attention.

Ingestion: rinse mouth thoroughly, drink water, induce vomiting. Seek medical attention. Fire extinguishing methods: carbon dioxide, dry powder, 1211 fire extinguishing agent, sand. Using water may cause boiling and splashing.