We've always thought of PCBs as a component of electronics, but we haven't thought about whether or not they're harmful to humans. They were discovered in the 19th century. At that time, automobiles began to be widely used and people's demand for gasoline was increasing. Gasoline is made from crude oil, which releases a lot of chemicals such as benzene. Benzene when heated, if combined with chlorine, will produce a kind of new chemicals, called Polychlorinated biphenyls al phenyl (Polychlorinated biphenyls, PCB). So far, PCBs have 209 related substances, numbered by the number of chlorine ions they contain and where they are inserted.

PCB properties and applications

PCB is an industrial chemical with the following properties:

1. Strong heat transmission, but no electricity transmission.

2. Insoluble in water, a fat-soluble substance.

3. It doesn't burn easily.

4. The property is stable and there will be no chemical changes.

Based on these characteristics, the industry initially saw PCBs as a god-given treasure, widely used as dielectrics, in electronic instruments such as capacitors and transformers, or as heat exchange fluids to regulate the temperature of instrument operation.

In the early days of PCB production, people didn't know about the toxicity of PCB and didn't take precautions against it. At the same time, a large amount of PCB waste was dumped into the ocean. People didn't start to pay attention to the problems caused by PCB until the industry workers who produced PCB began to get sick one after another, and when environmentalists found PCB content in Marine organisms.

PCB ingested is mainly stored in human adipose tissue and can be passed to the fetus through the placenta during pregnancy. It is also released into human milk.

The effect of PCB on human body

Redness and swelling of the eyes and discomfort of increased secretion

Liver and kidney damage

The nervous system response is slow, the hands and feet paralytic tremor, the memory decline, the intelligence development is blocked

Skin causes acne, redness and swelling, affecting pigment

Reproductive function interferes with the secretion of hormones and reduces the reproductive capacity of adults. Newborns are prone to developing birth defects and grow more slowly in later life.

Cancer, especially liver cancer. PCB has been listed as a possible carcinogen by the international organization for cancer research

PCB contamination is the result of years of accumulation, which can be said to be global. Almost all food is contaminated to some extent, which is difficult to completely avoid. What we can do is to pay attention to the food we eat, raise awareness and awareness of the environment, and hopefully encourage policy makers to make appropriate controls.