PCBs are identified as persistent, bioaccumulative and toxic (PBT). Because of their persistence, PCBs continue to be found in the environment and contamination from legacy sources remains a problem. In addition, PCBs are not prohibited in some products at concentrations below 50 ppm. PCB concentrations of less than 50 ppm are considered to be “PCB-free.”
Like many organochlorine compounds, many of the congeners are highly persistent and accumulate within food chains. Investigations in many parts of the world have revealed widespread distribution of PCBs in the environment. The universal distribution of PCBs throughout the world, suggests that PCBs are transported in air (2). The ability of PCBs to co-distil, volatilize from landfills into the atmosphere (adsorption to aerosols with a particle size of < 0.05–20 μm), and resist degradation at low incinerating temperatures, makes atmospheric transport the primary mode of global distribution. In a study in the USA, 92% of the PCBs detected were in the vapour phase (2). In a German study, congeners with a low degree of chlorination were dominant in filtered air, whereas those with a high degree dominated in aerosols and rainfall (2)
Health Effects of PCBs
Although PCBs are readily absorbed into the body, they are only slowly metabolized and excreted and a growing number of studies have found serious health effects from exposure to PCBs.
Bio-accumulation of PCBs in the organism
Some laboratory test on animals have shown that PCBs are easily absorbed through all exposed areas and remain for the most part in fatty tissue, where they tend to accumulate. More than 90% of ingested PCBs cross the intestinal walls and are retained in the organism. The organ favoured by PCBs is the liver, which stores them (the development of both malign and benign tumours has been observed in mice which have absorbed PCBs and in monkeys, whose sensitivity to these products is closest to that of humans).
Actual toxicity of PCBs
Studies of cases of poisoning caused by accidental absorption of doses measuring 800-1,000 mg/kg of PCB show that the first areas to show symptoms are the skin (acne, hyperpigmentation, keratosis, hypersudation) and the eyes (oedema of the eyelids, watering of the eyes). More general symptoms (fatigue, anorexia, weight-loss), liver disorders, bronchitis, certain peripheral neuropathies and endocrine disruptions complete the clinical picture. These symptoms recede after about a year.
Anomalies have been observed in the children of women who, during pregnancy, have consumed PCB-contaminated oil. These anomalies are primarily found on the skin, in mucous membrane and the epidermis. Occupational exposure can cause irritations of the skin and the mucous membrane (eyes and respiratory system), chloracne and, with stronger concentrations, liver disorders.
Carcinogenicity of PCBs
Epidemiological studies have shown no significant increase in the incidence of cancer among people exposed to PCBs. Skin, digestive and liver tumours, and also instances of leukaemia, have been attested, however, but scientific analyses have failed to establish a link between increased skin and pancreatic cancer rates and occupational exposure of the victims to PCBs. The International Agency for Research on Cancer (IARC), which is part of the World Health Organization (WHO), measures the carcinogenic risk of various chemicals and PCBs and places them in group 2 B: probably carcinogenic to humans with evidence “less well established”.
Toxicity of products resulting from the breakdown of PCBs
When PCBs are broken down by heat, they produce – first and foremost – chlorine, hydrochloric gas and carbon monoxide. Hydrochloric gas vapours can cause serious irritation of the respiratory tracts, exposed skin areas, the mucous membrane (particularly of the eyes), resulting in pharyngitis, laryngitis, bronchitis and inflammation of the eyes. In strong concentrations there is a risk of acute pulmonary oedema. Therefore, a transformer which has been damaged should never be sniffed. In the event of fire or decomposition, PCBs also produce, where oxygen is present, small quantities of toxic compounds which belong to the family of furans and dioxins.
The aim of this page is to show information on health effects, environmental impact, technical information and general information on polychlorinated biphenyls commonly known as PCBs. The main scope is to inform Serbian audience about National PCB Management Plan, all relevant legal framework and regulations in the Republic of Serbia and worldwide. This web page will help all potential PCBs owners to find all relevant information on technical guidelines, safety procedures, protocols and standard operating procedures for PCBs contaminated oils, equipment and soil, list of services, analytical procedures, laboratories, etc.
The Stockholm Convention on Persistent Organic Pollutants (POPs) was adopted by the Conference of Plenipotentiaries on 22 May 2001 in Stockholm, Sweden. The Convention entered into force on 17 May 2004.READ MORE
Polychlorinated biphenyls (PCBs) are aromatic, synthetic chemicals which do not occur naturally in the environment. They consist of the biphenyl structure with two linked benzene rings in which some or all of the hydrogen atoms have been substituted by chlorine atoms.
PCBs were first identified in the nineteenth century and started being manufactured on an industrial scale in 1929. They were intensively used between 1920 and 1980.READ MORE
PCBs are identified as persistent, bioaccumulative and toxic (PBT). Because of their persistence, PCBs continue to be found in the environment and contamination from legacy sources remains a problem.READ MORE