Assessment of cytotoxicity, genotoxicity and 7-ethoxyresorufin-O-deethylase (EROD) induction in sediment extracts from New Zealand urban estuaries

Abstract

Sediments represent a major sink for contaminants resulting from industrial and agricultural activities - especially lipophilic substances. This study exclusively used in vitro methodologies to characterize specific toxicity effects of contaminants in sediment extracts from two urban New Zealand estuaries. Sediment extracts were prepared and tested for a range of biological endpoints. The micronucleus and comet assays in V79 cells were used to assess genotoxicity. Induction of 7-ethoxyresorufin-O-deethylase in piscine RTL-W1 cells was determined to estimate dioxin-like toxicity. Cytotoxic potentials were analyzed by neutral red uptake and MTT reduction. There was evidence of strong dioxin-like toxicity and moderate cytotoxicity. Genotoxicity was distinct in the micronucleus assay, but low in the comet assay. The results indicate the presence of chemicals in the sediments with the potential to pose a risk through multiple mechanisms of toxicity, the identities and amounts of which will be disclosed in a parallel study alongside with in vivo toxicity data.

Peer Review #1 of "Assessment of the ecotoxicity of urban estuarine sediment using benthic and pelagic copepod bioassays (v0.1)"

“…The comet assay is a well recognised method to measure DNA damage in individual cells, and an accepted tool for environmental monitoring (Colin et al 2016;de Lapuente et al 2015;Martins & Costa 2014). The present study confirms the genotoxicity in the Old Tutaekuri samples, and the potential genotoxicity at the Humber drain, previously characterised with sediment extracts of organic compounds from the Ahuriri estuary (Boehler et al 2017;Heinrich et al 2017). The Humber Drain and Old Tutaekuri Riverbed sites had zinc and lead concentrations above guidelines values.…”

“…The Ahuriri Estuary is located north of the City of Napier (population 60,000), on New Zealand's North Island (39°30′S, 176°52′E) as described previously (Heinrich et al 2017). Four sites were selected: two were located 50m upstream from the Estuary at the Old Tutaekuri Riverbed, and at the Humber Street that is exposed to the Tyne Street stormwater drain network.…”

“…Smith (2014) reported the presence of contaminants above threshold limits in the Ahuriri Estuary. Recent studies using in vitro and zebrafish (Danio rerio) embryo tests showed that sediment extracts had genotoxicity, teratogenicity and acute toxicity (Boehler et al 2017;Heinrich et al 2017) Studies on chemical extracts can identify chemicals and provide insights into the mechanisms of toxicity but their ability to predict bioavailability or impact on whole organisms is limited (Burton 1991;Gyuricza et al 2010). Whole sediment assessments applying in vivo and in vitro approaches can complement extract studies by providing information closer to real field situations.…”

Biomarker responses and PAH ratios in fish inhabiting an estuarine urban waterway

“…Estuaries worldwide are increasingly subject to anthropogenic pressures in urbanized areas and several have been highly modified to suit human activities. Many estuaries which were of high ecological value are now heavily impacted by anthropogenic inputs, ranging from legacy contamination from registered contaminated sites to ongoing pollution via stormwater and industrial discharges …”

“…The objective was to assess the overall health status of black bream collected in a typical urban waterway (Claisebrook Cove). Specific aims were (1) to evaluate if fish are exposed to bioavailable contaminants at the remediated site of Claisebrook Cove; (2) to assess if the health status of the fish collected in Claisebrook Cove differs from the health in fish collected from a reference site (Burswood Lake); and…”