Negative impact on humans and the environment
PCBs have been produced industrially in many countries of the world over many decades and have been used in the electrical equipment, in composition of paints and lubricating oils.
Though PCBs production in the USA was forbidden in 1977, the majority of early produced PCB is still not only in the used-to-be electrical equipment but they also contaminate the soil, bed and waste deposits. Dioxins, furans and PCBs may exist in the environment for years. These substances are decomposed in fats and may bioaccumulate in the food chains.
The main sources of human exposure are meat, dairy products, finished products and fish contaminated with dioxins, furans and PCBs. Humans who live or work near POPs sources may receive the significant dose of persistent organic pollutants by their inhalation. Moreover even the small quantity of the toxicant can provoke a disease.
Dioxins, furans and dioxin-like PCBs differently affect human and animal health often under the low exposure level. Even the weak POPs concentrations show genotoxic, immunotoxic and cancerogenic effects, affect the level and functions of hormones, ferments and growth factors creating a real threat for health of present and future generations. Upon that the main difference between POPs ant other pollutants is POPs ability to accumulate in the environment over many decades and be transmitted through the food chains (water – water plants – plankton – fish – human; soil – plant – herbivorous animal – human). Thus POPs accumulate in the mammals’ tissues including humans’ where their final concentration doesn’t weaken but strengthen.
Scientific researches approve that POPs may be the reason of such diseases as chloracne, other skin diseases, malfunction of immune, reproductive, hormone, nervous systems; provoke diabetes, reduce lactation period of lactating mothers and provoke children mental retardation. Prenatal exposure at low level has a very strong toxic impact on development of the immune, reproductive and endocrine systems.
The role of dioxins, furans and dioxin-like PCB in the development of endometriosis and hyperplasia was actively researched after the report about high level of endometriosis diseases in the Rhesus macaque colony which receive small doses of dioxin along with their food (5 from 25 parties per trillion). Examination of these macaques after 10 years of exposure for dioxin showed that 70% of animals and more than 80% animals that received a large dose of dioxin have endometriosis in comparison with 33% of control animal group that weren’t the subject of dioxin impact.
The severity of disease was directly connected with the level of exposure for dioxin. The further examination of these animals after 13 years of exposure termination showed that endometriosis also passed in more severe form with animals with higher exposure for dioxin-like PCBs. As PCBs weren’t added to the animal food intentionally, the most probable sources of exposure were contaminated products as well as for human exposure. The authors noted that these determined impacts on the macaques can be of importance for human as the level of dioxins and PCBs in the animal blood is similar to the level of human blood and tissues.
These results provoke additional study in the animals. For another kind of monkeys dioxin raised their survival level and size of endometrial tissue that was surgically implanted into peritoneal cavity.
The same study of dioxin impact for the rising of survival level and size of endometrial tissue was made in gnawing animals.
The treating with small doses of dioxin before, during and after several weeks of surgery led to the enlargement and rising of survival level of implanted endometrial tissue. These studies were repeated with different changes and it was found out that this dioxin impact depends on the exposure time, dose size and other hormonal factors.
The study results of two kinds of monkeys, rats and mice approve the connection between endometriosis and exposure for dioxin or dioxin-like compounds. The study results for human are limited and less definite.
In one Israel research it was said that women with endometriosis more often have dioxin in their blood than woman without this disease.
Other most significant negative dioxin impacts for human health include:
- Neurobehavioral changes and changes in operation of thyroid body (malfunction of thyroid hormone synthesis) with babies that were fed on mother’s milk contaminated with POPs;
- Additional immunocompromise which can be provoked by POPs in the human organism even in very small doses;
- Honadotoxic, embriotoxic and mutagenic effects (it was detected genetic dioxin impact as fathers who are Vietnam war veterans in USA have the significant quantity of children with congenital deformity);
- Children mental and physical retardation;
- Reduction in life expectancy etc.