Persistent is a term applied to chemicals that do not break down easily in the environment. PBTs can be transported long distances through air and ocean currents. They can remain in the soil and silt for decades and be absorbed by plants and microorganisms.
Bioaccumulation is the build-up of a substance in an individual organism. If a PBT remains in silt, bottom feeders take in small quantities, which accumulate in fatty tissues more quickly than they can be metabolized. Predatory fish will then eat bottom feeders, storing larger quantities at higher concentrations in their own fat. The higher an animal is on the food chain, the more of the PBT the animal is likely to store and the more harm it may cause. As a result, once a PBT chemical is released into the environment it will accumulate and persist in fatty tissues of animals and end up in the food chain, concentrating on the top, affecting mainly predators such as fish, predatory birds and mammals (e.g. Polar bears, seals, whales), including humans. It is the phenomenon called biomagnification.
Toxicity includes harm not only to humans but also to individual animals and entire food chains. Toxic effects may include cancers, physical or behavioural reproductive problems, or damage to the endocrine and nervous systems, among others.
Evidence of these effects is the detection in the Northeast Atlantic of organochlorides such as DDT and PCBs in all species of marine mammals that have been analyzed.
(very) Persistent, (very) Bioaccumulative and/or Toxic chemicals (PBT and/or vPvB) are substances of very high concern because of their persistence, their ability to accumulate in living organisms, their capacity of travelling long distances and mainly their high toxicity.
Because of their persistence and mobility, Persistent Toxic Pollutants know no borders, they are found literally everywhere in the world and have polluted, not just the areas near the sources of origin, but also hidden places on the planet, even at the Antarctica and other remote islands of the Pacific. This shows the existence of a global circulation of synthetic chemicals, so pollutants produced or used in industrialized areas are disseminated through ocean currents and atmospheric transport to remote areas of the planet.
It is surprising that significant levels of these chemicals were detected in supposedly pristine areas such as the Arctic, where there is no polluting activity, sometimes at concentrations higher than those found in the producing countries or in areas where these chemicals are used, due to the distillation process of these substances in cold areas of the planet. Animal tissues are also fatter in colder climates: fish, birds and mammals need thicker layers of fatty tissue as natural insulation against low temperatures. Indigenous peoples in the Arctic, whose traditional diets contain plenty of fatty foods, and often have no other means of nutrition, are among the ones with higher levels of pollutants in their bodies.
Persistent bioaccumulative and toxic (PBT) substances are therefore harmful chemicals that persist overtime (do not break down easily in the environment) and are especially hazardous for human health and ecosystems. These chemicals can be transported long distances through air and ocean currents and they accumulate in tissues of living organisms and exhibit an acute or chronic toxicity. They may therefore pose serious concerns for human and environmental health. The effects of PBTs range from cancer, endocrine disruption, reproductive dysfunction, behavioural abnormalities, birth defects, disturbance of the immune system, damage to the liver and nervous system, to the extinction of whole populations.
Other chronic effects of PBT in animals include:
thyroid dysfunction in birds and fish;
decreased fertility in birds, fish, crustaceans and mammals;
decreased hatching success in birds, fish and turtles;
serious birth deformities in birds, fish and turtles;
abnormal metabolic patterns in birds, fish and mammals;
abnormal behavioral patterns in birds;
demasculinization and feminization of fish, birds and mammals
defeminization and masculinization of female fish and birds;
danger to the immune systems in birds and mammals.
These are highly hazardous chemicals. Oslo for the Prevention of Marine Pollution by Dumping from Ships and Aircraft (OSPAR) and the Paris Convention on land-based sources of marine are committed to eliminate dumping of these chemicals into the sea by 2020. The OSPAR Convention was signed by the European Union. The EU policy on chemicals also sets as a priority the eliminations of these substances. These substances are classified as chemicals of high level of concern by REACH Regulation.
While many toxic substances become less potent over time, PBTs can become more harmful as they persist due to their activity in ecosystems. Some, like arsenic, occur naturally in many minerals, but most are manmade. Other naturally occurring ones, like mercury and lead, are released into the environment in greater concentrations due to human activities like coal burning.
Given their persistence and capability to accumulate in the tissues of living organisms no safe levels of exposure, emission or dumping can be established for PBT and vPvB substances.
Due to their intrinsic characteristics PBTs’ presence at workplaces must be considered as a high level of risk. Occupational and environmental exposure must be avoided. Elimination and substitution are therefore priority prevention measures and only in those cases where this is not technically feasible, other measures must be adopted to reduce human (collective and personal protection measures) and environmental exposure (avoiding discharges and emissions) according to the principles expressed in Occupational Health and Safety legislation.
Specifically, women in fertile age, pregnant and lactating mothers must avoid exposure.
There is no unified model for the classification of PBT substances. However, several classification systems have been proposed based on their chemical structure, chemical or physical properties, effects, and other characteristics.
Substances of high level of concern published by OSPAR, the Oslo Convention for the Prevention of Marine Pollution by Dumping from Ships and Aircraft and the Paris Convention for the Protection of the Marine Environment of the North-East Atlantic have been selected for developing this list. Screening criteria can be found at OSPAR’s website.
A list of PBT substances has been published in 2007 by the EU-27 as part of the interim-strategy between the former European Chemicals legislation on chemicals and REACH. PBT Information System provides with information on Existing Substances which have been subject to evaluation of their PBT properties under the Interim Strategy for REACH and the ESR program. 127 Existing Chemicals and 101 New Substances respectively were evaluated for their PBT/vPvB properties. For the moment, nevertheless, it only comprises 27 substances, all of them already included in the OSPAR list.
On the other hand, under REACH Regulation, Annex XIII also includes criteria for identifying substances which are persistent, bioaccumulative and toxic and very persistent and very toxic. The current criteria of Annex XIII cover less PBT substances that those set by OSPAR.
Scientific evidence behind OSPAR PBT substances list is strong enough to include these chemicals in our priority list.
OSPAR Convention for the Protection of the Marine Environment of the North-East Atlantic.
Regulation (EC) No 1907/2006 of the European Parliament and of the Council of 18 December 2006, concerning the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH)
Council Directive 67/548/EEC of 27 June 1967 on the approximation of laws, regulations and administrative provisions relating to the classification, packaging and labelling of dangerous substances.
We use cookies analytics and similar technologies on our web site to improve performance and web browsing. Continuing to use our web site indicates your consent to their use
Start your search
