Toxicity mechanisms and interactions of polychlorinated biphenyls and polybrominated diphenylethers

Abstract

Polychlorinated biphenyls (PCBs) and brominated flame retardants, polybrominated diphenylethers (PBDEs), are widespread environmental contaminants as a result of anthropogenic activities and due to their persistency and resistance to degradation. Both groups of chemicals are placed on the list of persistent organic pollutants (POPs), covered by the Stockholm convention which is aimed to limit or ban the production, use, emission, import and export of POPs in order to protect human health and the environment. Taking into account the structural similarity between PCBs and PBDEs, and the known effects of PCBs, these two groups of chemicals could have similar mechanisms of action. Also, because of real simultaneous exposure to these compounds, an examination of possible interactions is of great importance. Interactions of the compounds from these groups are likely at the system level of hormones, particularly thyroid and reproductive ones. As there are mechanisms of adverse effects of both groups of chemicals on the nervous system, including functional, neurological and behavioral changes, there are influences on neurotransmiters, changes in signal transduction and apoptosis. There are interactions affecting the occurrence of metabolic disorders as well. Data on the toxicity of mixtures of PCBs and PBDEs, as well as interactions of these chemicals would contribute to the processes of risk evaluation and risk characterisation.

Polihlorovani bifenili (PCBs) i bromovani usporivači gorenja, polibromovani difenil etri (PBDEs) su široko rasprostranjeni u životnoj sredini kao posledica antropogenih aktivnosti i zahvaljujući njihovoj postojanosti i otpornosti na degradaciju. Obe grupe jedinjenja se nalaze na listi perzistentnih organskih zagađivača (POPs) usvojenoj Stokholmskom konvencijom sa ciljem da zabrani ili ograniči proizvodnju, upotrebu, emisiju ili uvoz i izvoz toksičnih supstanci označenih kao POPs u svrhu zaštite zdravlja ljudi i životne sredine. Uzimajući u obzir strukturnu sličnost između PBDEs i PCBs, kao i činjenicu da je istovremena ekspozicija ovim jedinjenima realna, ispitivanja njihovih interakcija su od značaja za predviđanje rezultujućeg efekta. Saznanja u oblasti toksikologije smeša, takođe doprinose procesu evaluacije i karakterizacije rizika. Interakcije jedinjenja iz ovih grupa su verovatne na nivou endokrinog sistema, naročito tiroidnog i reproduktivnog. S obzirom na mehanizme toksičnosti obe grupe supstanci za nervni sistem, uključujući funkcionalne promene, neurološke poremećaje i promene u ponašanju, moguće je očekivati njihove interakcije i na sistemima neurotransmitera, promene u prenosu signala i izazivanje apoptoze, kao i na pojavu metaboličkih poremećaja.