Toxicity of persistent organic pollutants: a theoretical study

Area of Science:

• Environmental Chemistry
• Computational Chemistry
• Toxicology

Background:

• Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are persistent organic pollutants found globally, including in Antarctic penguins.
• These compounds pose risks due to their persistence and toxicity, with oxidative stress implicated as a key mechanism.
• Previous research indicates PCBs and PBDEs are present in Antarctic wildlife, raising concerns about ecosystem health.

Purpose of the Study:

• To investigate the oxidative stress potential of PCBs and PBDEs found in Antarctic penguins using theoretical methods.
• To analyze the electron transfer properties and DNA interaction capabilities of these pollutants.
• To explore the role of quinone metabolites in the neurotoxicity of PCBs and PBDEs.

Main Methods:

• Density Functional Theory (DFT) computations were employed using Gaussian16 at the M06-2x/6-311+g(2d,p) level.
• Global reactivity descriptors, including electro-donating (ω-) and electro-accepting (ω+) powers, were utilized.
• Local reactivity was assessed using condensed Fukui functions.

Main Results:

• Compounds with a higher number of chlorine or bromine atoms exhibited greater oxidizing potential and induced more oxidative stress.
• Investigated PCBs and PBDEs demonstrated direct interaction with DNA nitrogenous bases via hydrogen bonding.
• Analysis of quinone-type metabolites suggested a potential link to neurotoxicity.

Conclusions:

• The number of halogen atoms directly correlates with the oxidative stress induced by PCBs and PBDEs.
• Interaction with DNA bases provides a plausible mechanism for the observed toxicity of these pollutants.
• DFT-based reactivity analysis offers valuable insights into the environmental risks posed by PCBs and PBDEs.