Ecotoxicological assessment of valproic acid in aquatic organisms

Introduction

Due to increased use of antiepileptic medications (AEDs) and lack of efficient wastewater treatment strategies, these drugs are frequently found in aquatic environments. Their presence in water endangers both fauna and flora, threatening the life of aquatic organisms. Valproic acid (VPA), a commonly prescribed AED, is a known human teratogenic drug, although its effects on aquatic organisms are still poorly understood.

The aim of this study is to evaluate the effects of VPA on aquatic organisms commonly used in ecotoxicological studies, Lemna minor, Daphnia magna and Chlorella vulgaris.

Methods

The following tests used VPA concentrations ranging from 1 to 100 mg/L. Acute growth inhibition tests were realised on Lemna minor and C.vulgaris. L.minor was exposed to VPA for 7 days and the number of fronds, growth rate and root length were analysed. C.vulgaris was exposed to VPA during 48h and the growth rate and % of inhibition were analysed. A chronic toxicity study was performed to evaluate VPA effects on D.magna. These organisms were exposed to six concentrations of VPA for 21 days and several parameters related to Daphnia’s reproduction and growth were analysed. All tests were performed according to OECD and standard endpoints were quantified, including EC₅₀, NOEC and % inhibition.

Results

VPA decreased the number of fronds, growth rate, root length and pigmentation of L.minor and inhibited C.vulgaris growth. This AED affected the reproduction of D.magna, delaying the age at the first posture and reducing the growth rate of the mothers, as well as affecting the number, viability and length of the offspring.

Conclusion

VPA has several harmful effects on the viability and reproduction of the organisms tested, which highlights the potential danger of VPA on aquatic environments. More research should be done to elucidate the environmental concentration of this drug and eventual removal techniques.