Dear readers, since Monday 20th of November I can tick a new box when I book my flights because I’m a doctor. The title is doctor in Environmental Engineering, but I say doctor in Environmental Chemistry as it better decribes the content of my thesis, which I summarise here.
During the last couple of decades the demand for good quality water in sufficient quantity has increased. The administration is now aware that water is not a commercial product; that hydrological management needs to be implemented to promote respect for the environment and a sustainable use of this natural resource. Consequently, directives have been developed to ensure the good status of water regarding quality and quantity. They establish requirements for avoiding new emissions of pollutants, reducing the current pollution.
Organic contaminants include a wide range of families. Some are grouped under the name persistent organic pollutants (POPs). The Stockholm Convention describes POPs as persistent in the environment, bioaccummulable, with potential for long-range transport and with adverse effects on human health and the environment. By mid 2017, the Stockholm Convention included polybrominated diphenyl ethers (PBDEs) and hexabromocylcododecane (HBCD). There are still other organic compounds. Even though they are not all persistent, some are considered pseudo-persistent contaminants as they are used in big quantities and they have a biological effect. That makes them always present in the environment and a possible threat. Pyrethroid pesticides are an example.
My thesis focuses on the descriptors of the Marine Strategy Framework Directive saying that concentrations of contaminants should be low enough not to produce pollution effects and contaminants in seafood cannot exceed the regulated limits.
The occurrence and behavious of the following compounds is analysed: well known and studied POPs, legacy flame retardants (FRs) (PBDEs and HBCD), along with new FRs (dechloranes and three brominated FRs and pseudo-persistent pyrethroid insecticides. FRs are applied to materials to increase their fire resistance. The classic ones are persistent, they are easily released to the environment and can be found in all kind of environmental matrices. Pyrethroids seem ideal because, at first, they were believed not to bioaccumulate. However, they have toxic effects and are used in big quantities.
In this thesis the behaviour in the marine environment of classic flame retardants is compared to new flame retardants and pyrethroids. The samples used in the analyses are marine mammals from the Mediterranean Sea, the Indian Ocean and the Antarctica on one side and seafood on the other. With these impact on both biota and humans is assessed.
Looking at the results, dechloranes outstood with occurrences similar to PBDEs’ and HBCD’s, with potential for long-range transport and increasing levels through time. They could be a candidate to be listed in the Stockholm Convention. Brominated new FRs in general were not detected or non-quantifiable. They must be monitored to see if they remain like this. Finally, the occurrence of pyrethroids, pseudo-persistent contaminants, seemed to be linked to their use. An excessive use might make them as dangerous as POPs. Regarding seafood safety, there is no risk, although a PBDE congener might pose a threat. New factors such as the effects of cooking and the bioaccessibility of ingested contaminants need to be studied to make better risk assessments.