Evaluation of the Developmental Toxicity of Metal-Contaminated Sediments Using Short-Term Fathead Minnow and Frog Embryo-Larval Assays

Abstract

The effects of metal-contaminated sediment extracts and a reference toxicant (zinc sulfate) were determined by examining the developmental morphology, growth and mortality of exposed fathead minnow (Pimephules promelus) and frog (Xenopus luevis) embryos. Sediments from two contaminated stream sites were extracted with reconstituted culture water at various pH values for 24 h. Developmental toxicity tests were performed using the frog embryo teratogenesis assay-Xenopus (FETAX) protocol. The results suggest that Zn was the major developmental toxicant in the sediment extracts. The measured Zn concentration in the sediment extracts that caused malformation in 50% of the fish embryos (EC50) was 0.5 t o 1.4 mg/L (normalized to 100 mg/L hardness). EC5O values for the reference toxicant tests were 0.6 and 0.8 mg/L Zn. The frog embryo EC50 for the extracts ranged from 2.2 to 3.6 mg/L Zn and was 3.6 mg/L Zn in the reference toxicant test. In 67% of the tests, malformation was a more sensitive endpoint than growth inhibition. Mortality was the least sensitive endpoint, that is, the LC50s in the reference toxicant tests were 3.6 mg/L Zn for the fathead minnow and 34.5 mg/L for the frog. The extraction procedure may be useful for determining potential toxicity in the event metals are leached from aquatic sediments by dredging or acidification.

The effects of heavy metals on embryonic development of fish (a review)

“…To quantify the degree of abnormality in Hgexposed Fundulus heteroclitus, Weis et al (1982) developed a craniofacial index (CFI) in which each embryo's convergence of the eyes was graded on a scale of 0-6, where: 0 = normal, 1 = slight convergence, 2 = greater convergence to touching, 3 = synophthalmia, 4 = fusion into one median eye with two lenses, 5 = cyclopia and 6 = anencephalia. In zinc-exposed Pimephales promelas embryos, Dawson et al (1988) reported incomplete gut coiling, skeletal kinking, edema in the dorsal fin, fin blistering, edema around the eyes, improperly formed mouth, head and eye, and brain reduced in size. Copper and cadmium caused a reduction of pigmentation, and chromium caused deformation of the notochord of Clarias gariepinus (Nguyen and Janssen 2002).…”

Altered developmental toxicity caused by three carrier solvents

“…The malformation caused by 0.002% (v/v) TCE and 2.0% (v/v) TG was increased significantly by 17.2% (10. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24].67'0; 95% confidence interval). Because both the malformation and mortality for T G showed an increase of approximately the same magnitude, the TI would not be expected to change.…”

Evaluation of the developmental toxicity of five compounds with the frog embryo teratogenesis assay: Xenopus (FETAX) and a metabolic activation system

“…9 Determined by Litchfield-Wilcoxon probit analysis with 95% confidence interval in parentheses. Concentrations normalized to 100 pg m l -hardness (as CaC0,) 14 …”