Full–Life Cycle Toxicity Assessment of Sediment‐Bound DDT and Its Degradation Products on Chironomus dilutus

Abstract

Because of its hydrophobicity and persistence, dichlorodiphenyltrichloroethane (DDT) is ubiquitous in sediments and poses significant risk to benthic organisms. Therefore, it is imperative to evaluate the long‐term toxicity of DDT. However, limited information is available on its chronic toxicity to benthic invertebrates. Full–life cycle toxicity of sediment‐bound DDT to Chironomus dilutus was assessed. Median lethal concentrations (with 95% confidence limits) of DDT and its degradation products (DDX) to C. dilutus were 334 (165–568), 21.4 (11.2–34.3), and 7.50 (4.61–10.6) nmol/g organic carbon after 10‐, 20‐, and 63‐d exposure, respectively. In addition, median effect concentrations of DDX were 20.0 (15.0–25.3), 7.13 (4.10–10.5), and 8.92 (3.32–15.1) nmol/g organic carbon for growth, emergence, and reproduction, respectively. A toxicity spectrum was established to visually summarize chronic effects of DDX to midges. In addition, DDT degraded to dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE) during sediment aging, and their toxicity differed from that of the parent compound. Predicted toxic units of DDX in porewater were utilized to distinguish between toxicity from DDT and that of DDD and DDE. The results showed that DDD was the main contributor to the toxicity in C. dilutus. To improve the accuracy of sediment risk assessment of DDT, the composition of DDX should be considered. Environ Toxicol Chem 2019;38:2698–2707. © 2019 SETAC

Isotopically Modified Bioassay Bridges the Bioavailability and Toxicity Risk Assessment of Metals in Bedded Sediments

“…Sediment toxicity was assessed by determining adverse effects to the chironomid emergence process (time and rate) following the standard protocols with minor modifications. ,, Briefly, 20 first-instar chironomid larvae (5 days after hatching) were added into the sediments on day 0 and their emergence process was monitored over the course of the experiment. They were fed daily by adding crushed fish food directly into the chamber (20 mg day –1 for days 1–10 and then 40 mg day –1 for days 11–21).…”

Contaminated aquatic sediments

“…The approach identified a limited number of contributors (acidic pH, sulfate, and Cu) to toxicity, but the added use of toxicity identification evaluations revealed acidic pH as the main cause. Ma, Li, Li, and You (2019) evaluated the toxicity of DDT in sediment to the benthic invertebrate Chironomus dilutus . They observed that the main contributor of toxicity to C. dilutus was not the DDT but a degradation product dichlorodiphenyldichloroethane (DDD) that was produced over time.…”

Response of Chironomidae (Diptera) to DDT, Mercury, and Arsenic Legacy Pollution in Sediments of the Toce River (Northern Italy)

“…According to published literature, these organisms may be sensitive to DDT, Hg, and As. DDT exposure is known to affect Chironomus emergence, mortality, reproduction, growth, and sex ratio [ 24 , 25 ]. Exposure to Chironomus riparius to Hg has been reported to reduce growth and emergence, delay development time, and decrease activity of the larvae [ 10 ], and increase morphological deformities [ 26 ].…”