Bioluminescent yeast assay for detection of organotin compounds.

Organotin compounds are toxic and endocrine disrupting compounds, which have been intensively used as antifouling paints for ship hulls and thus are widely spread in the environment. They are suspected to cause imposex, the formation of male characteristics in female gastropods, because of the activation of retinoid X receptor (RXR) at very low environmental concentrations. Here we report the development and optimization of a bioluminescent yeast assay for the detection of organotin compounds based on the interaction with a hybrid RXR and subsequent expression of a reporter luciferase gene. This assay is highly specific toward organotin compounds and natural ligands of the RXR. It detects tributyltin and triphenyltin in nanomolar concentrations (detection limits were found to be 30 nM and 110 nM, respectively) and allows small-scale high-throughput analyses. Furthermore it was possible to measure tributyltin directly in untreated spiked sediments. Thus, the results provided within one working day can be used for the assessment of bioavailability and mixture effect of organotin compounds in environmental samples.

Identification of Toxicants from a Highly C10 -C40 -Contaminated Sediment Influenced by the Wood Industry: Petroleum Hydrocarbons or Biogenic Organic Compounds?

Sediment from a log pond located in south Finland contained 15 000 to 50 000 mg/kg dry weight of C10 -C40 hydrocarbons. It was unclear whether they originated from the hydraulic fluid of the log hoist or the wood extractives. In the present study, methods of effect-directed analysis were used for the identification of toxicants. A combination of fractionation, biotesting, and chemical analyses revealed that the key toxicant of log pond sediment was retene, a dialkyl-substituted phenanthrene derived from wood resin acids. In addition, the most toxic fraction included 3 other wood-originated diterpenic compounds. Typical wood extractives such as sesquiterpenes and odd-carbon number alkanes in the range C21 -C33 were identified in the fraction, which showed minor genotoxic potency. The most polar fraction contained triterpenes and showed estrogenic activity. No evidence for the presence of hydraulic fluid in sediment was found. The study also indicated that in cases where the organic matter content of sediment or soil is high, using the results of standard mineral oil analysis in risk management can lead to incorrect actions because standard methods do not differentiate petroleum hydrocarbons from biogenic hydrocarbons. Environ Toxicol Chem 2019;9999:1-11. © 2019 SETAC.

Commercial processed food may have endocrine-disrupting potential: soy-based ingredients making the difference.

Processed and packaged food items as well as ready-to-eat snacks are neglected and poorly characterised sources of human exposure to endocrine-disrupting chemicals (EDCs). In this study we investigated the presence of xenoestrogens in commercially processed and packaged Finnish foods, arising from substances deliberately added or inadvertently contaminating the food, substances formed as a result of food processing, or substances leaching from food packaging materials. Samples were obtained in three separate batches of equivalent products from both a supermarket and a local representative of a global chain of hamburger restaurants and extracted by a solid-phase extraction method. Their endocrine-disrupting potential was determined by yeast bioluminescent assay, using two recombinant yeast strains Saccharomyces cerevisiae BMAEREluc/ERα and S. cerevisiae BMA64/luc. In this test system, the majority of samples (both foodstuffs and wrappers) analysed proved negative. However, all batches of industrially prepared hamburgers (but not those obtained from a hamburger restaurant) as well as pepper salami significantly induced luciferase activity in the BMAEREluc/ERα yeast strain indicating the presence of xenoestrogens, with estradiol equivalents of these products ranging from 0.2 to 443 pg g(-1). All three products contained soy-based ingredients, which apparently accounted for, or at least contributed to, their high estrogenic activity, since no signal in the assay was observed with extracts of the packaging material, while two different soy sauces tested yielded an intense signal (28 and 54 pg ml(-1) estradiol-equivalent). These findings imply that by and large chemicals arising in the processing or packaging of foodstuffs in Finland constitute an insignificant source of xenoestrogens to consumers. However, soy-derived ingredients in certain food items might render the entire products highly estrogenic. The estrogenic activity of soy is attributed to isoflavones whose health effects - though widely considered beneficial - are controversial. As hamburgers are a popular type of food among children, the findings are noteworthy and possibly of concern.

Fate of bisphenol A during treatment with the litter-decomposing fungi Stropharia rugosoannulata and Stropharia coronilla.

Bisphenol A is an endocrine disrupting compound, which is ubiquitous in the environment due to its wide use in plastic and resin production. Seven day old cultures of the litter-decomposing fungus Stropharia coronilla removed the estrogenic activity of bisphenol A (BPA) rapidly and enduringly. Treatment of BPA with purified neutral manganese peroxidase (MnP) from this fungus also resulted in 100% reduction of estrogenic activity, as analyzed using a bioluminescent yeast assay, and in the formation of polymeric compounds. In cultures of Stropharia rugosoannulata, estrogenic activity also quickly disappeared but temporarily re-emerged in the further course of cultivation. LC-MS analysis of the extracted estrogenic culture liquid revealed [M-H](-) ions with m/z values of 219 and 235. We hypothesize that these compounds are ring fission products of BPA, which still exhibit one intact hydroxyphenyl group to interact with estrogen receptors displayed by the yeast.