Trine Eggen

Head of Department/Head of Research

(+47) 909 97 074
trine.eggen@nibio.no

Place
Ås Vollebekk

Visiting address
Postboks 115, 1431 Ås

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Abstract

Given the compound differences between tris(2-butoxyethyl)- and tris(2-cloroethyl) phosphate (TBOEP and TCEP, respectively), we hypothesized that exposure of juvenile salmon to TBOEP and TCEP will produce compound-specific differences in uptake and bioaccumulation patterns, resulting in potential formation of OHmetabolites. Juvenile salmon were exposed to waterborne TCEP or TBOEP (0.04, 0.2 and 1 mg/L) for 7 days. The muscle accumulation was measured and bioconcentration factor (BCF) was calculated, showing that TCEP was less accumulative and resistant to metabolism in salmon than TBOEP. Metabolite formations were only detected in TBOEP-exposed fish, showing seven phase I biotransformation metabolites with hydroxylation, ether cleavage or combination of both reactions as important metabolic pathways. In vitro incubation of trout S9 liver fraction with TBOEP was performed showing that the generated metabolite patterns were similar to those found in muscle tissue exposed in vivo. However, another OH-TBOEP isomer and an unidentified metabolite not present in in vivo exposure were observed with the trout S9 incubation. Overall, some of the observed metabolic products were similar to those in a previous in vitro report using human liver microsomes and some metabolites were identified for the first time in the present study. Toxicological analysis indicated that TBOEP produced less effect, although it was taken up faster and accumulated more in fish muscle than TCEP. TCEP produced more severe toxicological responses in multiple fish organs. However, liver biotransformation responses did not parallel the metabolite formation observed in TBOEP-exposed fish.

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Abstract

Following the ban of polybrominated diphenyl ether (PBDEs) flame retardants under well-documented toxicity issues, organophosphate such as tris(2-butoxyethyl) phosphate (TBOEP) and tris(2-cloroethyl) phosphate (TCEP) were considered as potential substitutes. Although TBOEP and TCEP are consistently detected in the aquatic environment, there are few data about the possible toxicological effects of these compounds on aquatic organisms, including fish. In the present study, we have investigated the influence of TBOEP and TCEP on neuro- and interrenal steroidogenesis of juvenile Atlantic salmon (Salmo salar), after a seven-day exposure to four different concentrations (0 (control), 0.04, 0.2 and 1 mg/L) of each compound. TBOEP and TCEP were diluted in Milli-Q water. The expression of genes involved in ster- oidogenesis (StAR, cyp19a, cyp19b, cholesterol side-chain cleavage enzyme (P450scc), 3β-hydroxysteroid dehydrogenase (3β-hsd), and 11β-hydroxylase (cyp11β)), were analyzed in the brain and head kidney using real-time PCR. Plasma 11-ketotestosterone (11-KT) analysis was performed using enzyme im- munoassay (EIA). Our results showed that TBOEP accumulated more rapidly than TCEP in fish muscle tissue. Surprisingly, TBOEP produced less pronounced effects than TCEP on neural and interrenal ster- oidogenic responses, despite the observed rapid uptake and bioaccumulation pattern. Specifically, TBOEP produced significant and consistent concentration-specific alterations on neural- and interrenal ster- oidogenesis. Plasma levels of 11-KT were not significantly altered by any of the exposures. The increased expression of steroidogenic genes demonstrated in the present study could produce time-specific al- terations in the production of glucocorticoids and steroid hormones that play integral roles in fish me- tabolism, stress responses and adaptation, sexual maturation, reproduction and migration with overt consequences on reproductive success and survival.

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Abstract

There is limited knowledge on the toxicological, physiological, and molecular effects attributed to organophosphate (OP) compounds currently used as flame retardants or additives in consumer products. This study investigated the effects on oxidative stress and lipid peroxidation in juvenile Atlantic salmon liver and brain samples after exposure to two OP compounds, tris(2-butoxyethyl) phosphate (TBOEP) and tris(2-chloroethyl) phosphate (TCEP). In this study, groups of juvenile Atlantic salmon were exposed using a semistatic experimental protocol over a 7-d period to 3 different concentrations (0.04, 0.2, or 1 mg/L) of TBOEP and TCEP. When toxicological factors such as bioaccumulation and bioconcentration, and chemical structural characteristics and behavior, including absorption to solid materials, are considered, these concentrations represent environmentally relevant concentrations. The concentrations of the contaminants were derived from levels of their environmental occurrence. The expression of genes related to oxidative stress—glutathione peroxidase (GPx), glutathione reductase (GR), glutathione S-transferase (GST)—and to lipid peroxidation—peroxisome proliferator-activated receptors (PPAR)—were determined using quantitative (real-time) polymerase chain reaction (PCR). The presence of PPAR proteins was also investigated using immunochemical methods. Levels of thiobarbituric acid-reactive substances (TBARS) in liver were used as a measure of lipid peroxidation. Overall, our data show an increase in lipid peroxidation, and this was associated with an augmented expression of genes from the glutathione family of responses. Interestingly, PPAR expression in liver after exposure to TBOEP and TCEP was consistently decreased compared to controls, while expression in brain did not show a similar trend. The results suggest that OP contaminants may induce oxidative stress and thus production of reactive oxygen substances (ROS), and modulate lipid peroxidation processes in organisms.

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Abstract

Residues of pharmaceuticals present in wastewater and sewage sludge are of concern due to their transfer to aquatic- and terrestrial food chains and possible adverse effects on non-targeted organisms. In the present work, uptake and translocation of metformin, an anti-diabetic II medicine, by edible plant species cultivated in agricultural soil has been investigated in greenhouse experiment. Metformin demonstrated a high uptake and translocation to oily seeds of rape (Brassica napus cv. Sheik and Brassica rapa cv. Valo). Expressed as an average bioconcentration factor, (BCF, plant concentration over initial concentration in soil, both in dry weight), BCF as high as 21.72 was measured. In comparison, BCFs for grains of the cereals wheat, barley and oat were in the range of 0.29 - 1.35. Uptake and translocation to fruits and vegetables of tomato (BCFs 0.02-0.06), squash (BCFs 0.12-0.18) and bean (BCF 0.88) were also low compared to rape. BCFs for carrot, potato and leaf forage Brassica napus cv. Sola were similar (BCF 1-4). Guanylurea, a known degradation product of metformin by microorganisms in activated sludge, was found in seeds from barley, beans and potatoes. The mechanisms for transport of metformin and guanidine in plants are still unknown, whereas organic cation transporters (OCTs) in mammals are known to actively transport such compounds and may guide the way for further understanding of mechanisms also in plants.

Abstract

Fire ulike komposter ble benyttet til å evaluere ulike kjemiske parameteres egnethet som stabilitetsindeks. Vannløselig TOC viste signifikant korrelasjon til biologisk aktivitet målt som respirasjonsrate, og foreslås som en mulig operasjonell parameter ved komposteringsanlegg.