The use of growth and behavioral endpoints to assess the effects of pesticide mixtures upon aquatic organisms

Simone Hasenbein, Sharon P. Lawler, Juergen Geist, Richard E Connon

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


Aquatic communities are often subject to complex contaminant mixtures, usually at sublethal concentrations, that can cause long-term detrimental effects. Chemicals within mixtures can effectively interact, resulting in synergism, antagonism or additivity. We investigated the tertiary mixture effects of two pyrethroids, lambda-cyhalothrin and permethrin, and the organophosphate chlorpyrifos, evaluating sublethal endpoints; immobility and growth, on Chironomus dilutus in 10-day exposures. We utilized a toxic units (TU) approach, based on median lethal concentrations (LC50) for each compound. The concepts of independent action and concentration addition were used to compare predicted mixture toxicity to observed mixture toxicity. Increased immobility resulted from mixture concentrations ≥1 TU (7.45 ng/L lambda-cyhalothrin × 24.90 ng/L permethrin × 129.70 ng/L chlorpyrifos), and single pesticides concentrations ≥0.25 TU (5.50 ng/L lambda-cyhalothrin, 24.23 ng/L permethrin, 90.92 ng/L chlorpyrifos, respectively). Growth was inhibited by pesticide mixtures ≥0.125 TU (1.04 ng/L lambda-cyhalothrin × 3.15 ng/L permethrin × 15.47 ng/L chlorpyrifos), and singly by lambda-cyhalothrin ≥0.25 TU (5.50 ng/L), and permethrin ≥0.167 TU (18.21 ng/L). The no observed effect concentrations (NOEC) for immobility and growth, for both mixture and single-pyrethroid exposure, were up to 8.0 and 12.0 times respectively lower than the corresponding NOEC for survival. The median effective concentrations (EC50) for growth (mixture and single-pyrethroid exposure) were up to 7.0 times lower than the respective LC50. This study reinforces that the integration of sublethal endpoints in monitoring efforts is powerful in discerning toxic effects that would otherwise be missed by solely utilizing traditional toxicity assessments.

Original languageEnglish (US)
Pages (from-to)746-759
Number of pages14
Issue number4
StatePublished - May 1 2015


  • Aquatic toxicology
  • Ecotoxicological risk assessment
  • Freshwater invertebrates
  • Mixture toxicity
  • Sublethal endpoints

ASJC Scopus subject areas

  • Health, Toxicology and Mutagenesis
  • Toxicology
  • Management, Monitoring, Policy and Law


Dive into the research topics of 'The use of growth and behavioral endpoints to assess the effects of pesticide mixtures upon aquatic organisms'. Together they form a unique fingerprint.

Cite this