Bio-based versus synthetic: comparative study of plasticizers mediated stress on Chironomus circumdatus...

Phthalates are used as plasticizers in products made of polyvinyl chloride to increase the flexibility of polymers. Unfortunately, these are known to cause adverse effects on living organisms, and also, fast depletion of petroleum resources calls for the exploration of alternatives as replacements. Recent developments in bio-based plasticizers have led to their use as additives for various applications. As they have received much attention in the past decade, it is crucial to study the effects of these plasticizers on living organisms. Hence, we tried to compare the effects of synthetic plasticizer dioctyl phthalate and bio-based plasticizer ethanolamine on Chironomus circumdatus larvae. Mortality was achieved at a lethal concentration (LC₅₀) value of 0.385 mg/L for ethanolamine and dioctyl phthalate at 0.125 mg/L. Disruption in the level of metabolites along with lipid peroxidation was observed in the larvae exposed to plasticizer mediated stress. To overcome these changes, an increase in the levels of antioxidant enzymes such as Superoxide Dismutase, Catalase, Glutathione Peroxidase and Glutathione Reductase, as well as in the levels of detoxifying enzymes like Glutathione-S-Transferase, Esterases and Mixed Function Oxidase during post-exposure recovery conditions was seen. Alterations in the expression levels of heat shock protein 70 and ecdysone receptor genes were also observed. From the comparative study, it could be concluded that Chironomus circumdatus larvae, to a certain extent, have developed tolerance to both ethanolamine and dioctyl phthalate mediated stress. However, dioctyl phthalate has led to more stress as compared to ethanolamine in these larvae.