Fish contain toxic substances PART 2
Today, cancer in fish is met more frequently than 50 years ago. National Cancer Institute in the US found a higher rate of cancer deaths among populations that areliving in the region where fish showed a very high frequency of malignancies. Application of the sediment collected from the bottom of Lake Erie, US, on mouse skin caused skin cancer. In connection with toxic substances and the livings that come in contact with polluted waters, is speak of two processes: bioaccumulation and bioamplification or biomagnification. Bioaccumulation is the process through toxins accumulate progressively in certain organs, especially in the animal’s fat.
Bioamplifiction is the process by which the toxins become progressively more concentrated, as it progresses on the nutritional scale. A classic example of bioamplification was found in a lake (Cleac Lake) in California, 150 km north of San Francisco. Above the lake was sprayed several times, DDD insecticide to reduce the insect population. DDD is a less toxic relative of the famous DDT. The results: in the water, the pesticide was barely detectable – two drops of DDD to 100 million of water drops. But bioamplification produced a marked increase in the tissues of organisms living in the water. DDD’s concentration on the phytoplankton of the contaminated water was 500 times higher than in lake’s water. In the herbivores fish that feed on water plants, concentrations were of 10,000 to 30,000 times higher than in water, and the carnivores fish that feed on herbivorous fish, concentrations were of 125,000 times higher than in water.
Environmental Protection Agency of the United States claims that aquatic organisms can bioaccumulate the environment contaminating more than one million times the concentration of the water. The bioaccumulation is met in people too. High levels of these toxic substances found in the tissues of women suffering from malignant breast tumors, but the problem is not limited to cancer.
Today, the largest quantities of polyvinyl diphenyl, which the population is exposed to, came from consumption of fish. In a research carried out in England, was found that, at age 11, children that were exposed to a large amount of polyvinyl diphenyl presented a disorder of the intellectual developing. Water changed due to acid rain can make that aluminum, manganese, lead, zinc, cadmium and mercury in seabed or soil to enter the water and, once issued, these toxic metals will find their way into the food chain, accumulating in the tissues of water livings.
Not even the fish that come from special breeders are not safe, for the following reasons:
- Illegally, in the waters are added colorants, for the fish to look more attractive;
- To prevent infections, antibiotics are used;
- The water these fish live in contains an appreciable amounts of pesticide.
Regarding to pesticides, the population fears more the fruit and vegetables contamination than the animals products. But absolutely all statistics show that, the more fruits and vegetables are consumed, the lower the cancerous disease risk is. Vegetable food contain a number of substances that protects us against malignancies. Although most fruits and the vegetables are sprayed with different substances and grow with chemical fertilizers, instead to increase the cancer risk, they protect us. And where the aslimentation is rich in vegetables are met the fewest tumor diseases.