PCB was discovered in the 19th century. So far, PCB contains 209 related substances, which are numbered differently according to the number of chloride ions contained and where they are inserted.
PCB is an industrial chemical with the following properties:
1. Strong heat transfer, but no electricity 2. Not easy to burn 3. Stable in nature 4. It will not dissolve in water and is a fat-soluble substance
Based on the above properties, the industry initially regarded PCB as a godsend treasure and was widely used as a dielectric, placed in electronic equipment such as capacitors and transformers, or as a heat flow exchange fluid to adjust the temperature of the operation of the instrument.
In the early days, people did not know that PCBs are toxic and did not take precautions against it. At the same time, a large amount of PCB waste is dumped into the ocean. People began to pay attention to the problems caused by PCBs until the workers in the PCB industry began to get sick one after another, and when environmentalists discovered PCB content in marine organisms.
How do chemicals in PCB enter the human body
PCB waste accumulated in landfills will release gas. Over time, these waste materials will flow into lakes or oceans. Although PCB is not soluble in water, it is soluble in oils, so that it accumulates in organisms in the ocean, especially larger organisms such as sharks and dolphins. When we eat such deep-sea fish, or eat other contaminated foods, including dairy products, meat fats, oils, etc., we inhale PCB chemicals. Ingested PCBs are mainly stored in human adipose tissue, and can be passed to the fetus through the placenta during pregnancy, and are also released in human milk.
The impact of PCB on the human health
Causes damage to liver and kidney; Causes skin acne, redness and swelling; Causes eyes red, swelling and discomfort, and increased discharge; Causes the nervous system to respond slowly, the hands and feet are numb and tremble, memory decline, and intellectual development is blocked; Interfere with hormone secretion and reduce adult reproductive ability. Newborn babies are prone to birth defects and slower growth in the future; Causes liver cancer. The International Organization for Cancer Research has listed PCB as a possible carcinogen
Control of PCB
In 1976, the U.S. Congress banned the production, sale, and distribution of PCBs. Since the 1980s, many countries, such as the Netherlands, the United Kingdom, and Germany, have imposed restrictions on PCBs. However, even with the restrictions imposed, between 1984-89, global production was still 22 million pounds per year.
The pollution of PCBs is a result of accumulation over the years, and it can be said to be global. Almost all foods are contaminated to some extent, and it is difficult to completely avoid it. What we can do is to pay attention to the food we eat, increase our awareness and concern about environmental protection, and hope that policy makers can make appropriate controls.