Acute and chronic toxicity assessment of haloacetic acids using Daphnia magna

ABSTRACT

Haloacetic acids (HAAs) are undesirable disinfection by-products (DBPs), released into aquatic ecosystems from various anthropogenic and natural sources. The aim of this study was to examine the ecological risk of exposure to three HAAs commonly detected in water, such as monobromoacetic acid (MBA), monochloroacetic acid (MCA), and trichloroacetic acid (TCA), in in vivo acute and chronic toxicity tests using Daphnia magna as a model. Acute tests showed that MBA was the most toxic of these compounds followed by MCA and TCA as evidenced by immobilization. Aquatic organisms in natural conditions might be exposed simultaneously to numerous compounds; thus, binary mixtures of selected HAAs and a ternary mixture of these were tested. Concentration addition (CA) and independent action (IA) models were used for a predictive assessment of mixture toxicity. Data demonstrated that CA appeared to be the most reliable indicator for HAAs binary and ternary mixtures suggestive of an additive behavior. Median effective concentration (EC₅₀) values from the mixed exposure tests were significantly lower than results obtained from single tests for all three HAAs where an increase of toxicity greater than 50%. Multigenerational chronic tests were also performed exposing daphnids to the ternary mixture of HAAs. A markedly decreased sexual maturity and number of offspring and broods per daphnid especially in the second generation were noted.

KEYWORDS:

• Daphnia magna
• disinfection by-products
• wastewater
• haloacetic acids
• ecotoxicity

Acknowledgments

The authors are greatly indebted to all financing sources (FEDER POCI/01/0145/FEDER/007265; FCT/MEC, Fundação para a Ciência e Tecnologia and Ministério da Educação e Ciência, under the Partnership Agreement PT2020 UID/QUI/50006/2013; SFRH/BPD/86898/2012). The authors thank Andreia Peixoto for the technical assistance with daphnids and algae.

Declaration of interest statement

The authors declare that they have no conflict of interest.

Additional information

Funding

This work received financial support from the European Union (FEDER funds POCI/01/0145/FEDER/007265) and National Funds (FCT/MEC, Fundação para a Ciência e Tecnologia and Ministério da Educação e Ciência) under the Partnership Agreement PT2020 UID/QUI/50006/2013. A. Melo wishes to thank the Fundação Ciência Tecnologia grant SFRH/BPD/86898/2012.