Scientists of the IDAEA-CSIC work to know the environmental impact of the new pollutants, like pyrethroid insecticides (of very common use, which are toxic and accumulative) or the new flame retardants, with similar toxic effects to the old flame retardants, already forbidden.
Laboratory IDAEA-CSICScientists from the Institute of Environmental Assessment and Water Research Studies (IDAEA) of the Spanish National Research Council (CSIC) work to discover new pollutants, the so-called emergent and, especially, the substances of common use that can present toxic properties. More precisely, the persistent organic pollutants because they are very stable and remain for a long time in the environment. Some of them bio-accumulate and even biomagnify.
His research sheds light on the impact of these substances in the environment and on alive organisms. It contributes also to improve the rules that regulate their use and the development of analytical technicians improved for the control of the pollutants in the environment or on food.
Some of the most recent works of this team of environmental chemists, directed by Ethel Eljarrat, researcher of the IDAEA, have focused on pyrethroid insecticides - with a study in fishes of several river basins on the Iberian Peninsula- and to the modern flame retardants, with another study on several species of dolphins from the Gulf of Cadis and the Strait of Gibraltar. At the moment scientists are undertaking a research in birds to check if they also bio-accumulate pyrethroids. Preliminary results show that these substances are on most of the analyzed samples.
Pyrethroids: from ideal insecticide to pseudo-persistent pollutant
The pyrethroid insecticides degrade in less than ninety days, so they are the most used insecticides in the world. They have been used as a substitute for organochlorine and organophosphate pesticides, which take longer to degrade. Pyrethroids were considered the ideal insecticide until recently: they were not persistent and it was thought that the mammals metabolized them and the nontoxic metabolites were expelled through the urine afterwards. This is the reason they are the most used insecticides in agriculture, livestock, fish farms, even in necklaces for dogs and cats or as domestic insecticide.
It is the first time that they find these insecticide in fishes, and in the one hundred percent of the samples analysed
Nevertheless, the generalised use of pyrethroids provokes that these could be found constantly in the environment. At the moment, a work led by Ethel Eljarrat has documented the presence of high concentrations of pyrethroids insecticides in fishes of several peninsular rivers. As the researcher indicates, “this substance has been found in all of the analysed samples. It is a very surprising thing because pyrethroids are not persistent pollutants”. This is the first time that pyrethroid levels have been found in fish. “The toxic effects in fishes would include cardiac and growth problems. The toxic consequences in human are not clear, but it may include neurologic effects and some of these substances has been classified as possibly carcinogenic to humans”, adds Ethel Eljarrat. Therefore, scientists think that they would have to be considered pseudo-persistent pollutants and have recommended their inclusion in the studies of control and environmental quality.
The new flame retardants also bio-accumulate
In addition to pyrethroids insecticides, rests of flame retardants PBDE and dechloranes have been found in almost all the analysed samples of river fishes. A very recent study with dolphins shows that also accumulate these flame retardants in their organism.
Flame retardants are substances added by law to many products such as a clothes, furniture or electronic devices, to minimize the risk of fire. Brominated flame retardants or PBDE (polybrominated diphenyl ethers) have been used since the 70s and most studies have analysed them. After it was demonstrated their bioaccumulation in alive organisms as well as their toxiciy, PBDE was forbidden in Europe in 2004 and included in 2011 in the list of toxic substances of the Convention of Stockholm: on May 22, 2001 a conference was celebrated in Stockholm (Sweden) under the auspice of the United Nations and the Agreement of Stockholm on Persistent Organic Pollutants was adopted. It entered into force in May of 2004. Afterwards new Persistent Organic Pollutants have been included on the list.
The studies being undertaken by the IDAEA on another flame retardant, the HBCD (Hexabromocyclododecane) were one of the first to detect it bioaccumulation in alive organisms, humans included. These studies and new data on his toxicity (it alters the thyroid hormone) give new evidences on this pollutant. It was also included on the list of Stockholm in 2014.
Dolphins, sensitive to accumulation of flame retardants
Long-finned pilot whale. Image: CIRCE.The research that has been carried out with dolphins and published in Environmental Pollution, shows that several species of these animals from the Gulf of Cadis and from the Strait of Gibraltar accumulate in his organisms flame retardants, not only the classical PBDE - now forbidden - but the new flame retardants, the dechloranes.
The investigation that leads the Institute of Environmental Diagnostic, and Studies of the Water, with the participation of the Biological Station of Doñana (CSIC) and Conservation, Information and Study on Cetaceans (CIRCE) It has been funded by the Loro Parque Foundation, in the framework of the FLAME project, CEPSA, the Ministry of Science and Innovation, in the framework of the Consolider SCARCE project and the Ministry of Economy and Competitiveness, in the framework of ECOCET project.
The researchers have showed that three species of cetaceans (common dolphin, longfinned pilot whale and bottlenose dolphin) which present different areas of distributions and diverse eating habits, accumulate and biomagnify flame retardants. This finding is very important because it shows that the higher up the food chain, more concentration of toxics. It was already known that forbidden PBDE biomagnifies, but this study represents one of the first that shows that new flame retardants, currently in use, also biomagnify.
At the moment, scientists have no evidence that pollutants called “PBT” (for “persistent, bio-accumulating and toxic”) cause a direct mortality on the marine mammals, but it is known that they cause immune and reproductive dysfunctions and it may have long-term consequences at their population level.
On the other hand, this pollution is not limited only to the marine environment. Another research of the IDAEA and of the Biological Station of Doñana (EBD), has also found flame retardants (PBDE and dechloranes) in bird eggs in the Doñana Natural Park. Ethel Eljarrat explains that having detected these compounds in eggs of a protected area, like Doñana, “reveals the extension these substances disperse themselves in the environment”.