Chlorinated paraffins
The contaminants pose a significant risk to the environment and human health. Among a relatively new and underexplored class of contaminants are chlorinated paraffins, which have replaced the high-risk polychlorinated biphenyls in many industry sectors.
Chlorinated paraffins are polychlorinated n-alkanes formed by radical chlorination initiated by UV light. According to the length of the carbon chain, they can be divided into short SCCP, medium MCCP, and long LCCP. SCCPs have been used in industry as flame retardants, metalworking fluids, and paints or sealant components. In 2017, however, SCCPs were classified as persistent organic pollutants under the Stockholm Convention. Their production and use are, therefore, restricted and regulated. However, as is common in the industry, after the prohibition of SCCPs, the market has shifted to a novel group of compounds, MCCPs, which have very similar properties, and therefore we expect similar environmental effects. The production of MCCPs is rising annually, potentially leading to severe ecological contamination that could take decades to remediate.
Like other organochlorine compounds, chlorinated paraffins are non-polar substances readily accumulating in fatty tissues. An important question regarding the in vitro action of CPs is whether CPs can penetrate the cell or affect cell physiology as extracellular agents. The answer to this question still needs to be clarified. On the other hand, SCCPs have been found to cause indirect and direct toxicity. In addition to in vitro cellular models, chlorinated paraffins have been studied using animal models ranging from snakes and frogs to chickens and various other birds to laboratory mice and rats. Significant accumulation of SCCPs and MCCPs was observed in all organisms under investigation.
CPs have also been found in biological matrices such as plasma, placenta, umbilical cord blood and breast milk. Both SCCPs and MCCPs have been shown to cross the placenta into the fetus and subsequently into the body of newborns through breastfeeding. Data from biomonitoring studies on the presence of CP in human tissues are limited, as most CP studies focus only on China, the largest producer and consumer of CP.
Any further knowledge in the field of chlorinated paraffins may lead to the determination of their effects on living organisms and potentially restricting or banning their use in industry.
