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- Ulhaq, Mazhar, et al.
(författare)
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Tissue uptake, distribution and elimination of C-14-PFOA in zebrafish (Danio rerio)
- 2015
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Ingår i: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 163, s. 148-157
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Tidskriftsartikel (refereegranskat)abstract
- Perfluorooctanoic acid (PFOA) is a long-chain perfluorinated chemical that has been shown to be non-degradable and persistent in the environment. Laboratory studies on bioconcentration and compound-specific tissue distribution in fish can be valuable for prediction of the persistence and environmental effects of the chemicals. In the present study male and female zebrafish (Danio redo) were continuously exposed to 10 mu g/L of radiolabeled perfluorooctanoic acid (C-14-PFOA) for 40 days, after which the exposed fish were transferred to fresh clean water for another 80 days wash-out period. At defined periodic intervals during the uptake and wash-out, fish were sampled for liquid scintillation counting and whole body autoradiography to profile the bioconcentration and tissue distribution of PFOA. The steady-state concentration of C-14-PFOA in the zebrafish was reached within 20-30 days of exposure. The concentration-time course of C-14-PFOA displayed a bi-exponential decline during washout, with a terminal half-life of approximately 13-14 days. At steady-state the bioconcentration of C-14-PFOA into whole-body fish was approximately 20-30 times greater than that of the exposure concentration, with no differences between females and males. The bioconcentration factors for liver and intestine were approximately 100-fold of the exposure medium, while in brain, ovary and gall bladder the accumulation factors were in the range 15-20. Whole-body autoradiograms confirmed the highest labeling of PFOA in bile and intestines, which implies enterohepatic circulation of PFOA. The C-14-PFOA was also observed in maturing vitellogenic oocytes, suggesting chemical accumulation via yolk proteins into oocytes with plausible risk for adverse effects on early embryonic development and offspring health. The bioconcentration at several C-14-PFOA exposure concentrations were also investigated (0.3-30 mu g/L). This showed that bioconcentration increased linearly with tank exposure in the present in vivo model under steady-state conditions. From this model tissue concentrations of PFOA can be predicted when the external exposure level is known. The present study has generated experimental data on PFOA kinetics in zebrafish that can be valuable for aquatic environmental risk assessment.
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| 2. |
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| 3. |
- Ul haq, Mazhar, et al.
(författare)
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Comparison of developmental toxicity of seven perfluoroalkyl acids to zebrafish embryos
- 2013
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Ingår i: Environmental toxicology and pharmacology. - : Elsevier BV. - 1382-6689 .- 1872-7077. ; 36, s. 423-426
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Tidskriftsartikel (refereegranskat)abstract
- The toxicity of individual perfluoroalkyl acids (PFAAs) has been suggested to be determined by the carbon chain length as well as the functional group attached. We tested seven different PFAAs including both sulfonic and carboxylic PFAAs with different chain length to evaluate the developmental toxicity in zebrafish embryos. Generally, the acute toxicity of PFAAs is relatively low to zebrafish embryos. The EC50 values ranged from 1.5 to 2200 mg/L. We observed a relationship between higher toxicity with longer carbon chain. In addition, we also observed a higher toxicity for sulfonic PFAAs than for carboxylic PFAAs. (C) 2013 Elsevier B.V. All rights reserved.
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| 4. |
- Ul haq, Mazhar, et al.
(författare)
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Locomotor behavior in zebrafish (Danio rerio) larvae exposed to perfluoroalkyl acids
- 2013
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Ingår i: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 144, s. 332-340
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Tidskriftsartikel (refereegranskat)abstract
- Perfluoroalkyl acids (PFAAs) are persistent organic contaminants that have been detected in wildlife, humans and the environment. Studies have shown that the toxicity of PFAAs is determined by the carbon chain length as well as the attached functional group. The locomotor activity of zebrafish larvae has become widely used for evaluation of chemicals with neurotoxic properties. In the present study the behavioral effects of seven structurally different PFAAs (i.e. TFAA, PFBA, PFOA, PFNA, PFDA, PFBS and PFOS) were evaluated in zebrafish larvae. Exposure to high concentrations of TFAA, PFNA, PFBS and PFOS resulted in distinct changes in behavioral patterns. Based on redundancy analysis, our results demonstrate three main factors affecting zebrafish larval locomotor behavior. The strongest effect on behavior was determined by the carbon chain length and the attached functional group. PFAAs with longer carbon chain length as well as PFAAs with attached sulfonic groups showed larger potential to affect locomotor behavior in zebrafish larvae. Also the concentration of the PFAAs determined the behavior responses. The results of the present study are in agreement with previous studies showing correlations between the chemical structure of PFAAs and the toxicological effects. (C) 2013 Elsevier B.V. All rights reserved.
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| 5. |
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| 6. |
- Ul haq, Mazhar
(författare)
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The toxicity of perfluoroalkyl acids in zebrafish (Danio rerio)
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Perfluoroalkyl acids (PFAAs) are globally distributed synthetic chemicals. Their unique properties make them widely used, in industry and elsewhere. These are a group of compounds with varying carbon chain lengths and functional groups. The toxicity evaluation of PFAAs is important to better assess their organismal and environmental impact. The developmental toxicity of a group of PFAAs was evaluated in zebrafish (Danio rerio), using the embryotoxicity and locomotor behavior endpoints. Structure related relationships were examined using endpoints based on lethal and sublethal effect. The EC50 based toxicity ranking of the PFAAs indicated that the toxicity pattern was governed by carbon chain length and attached functional group. The behavior analyses showed that the PFAAs have distinct patterns in terms of locomotor activity of larvae. Radiolabeled 14C-PFOA was used to investigate the uptake, kinetics and distribution of the chemical in zebrafish. An uptake and elimination approach to experimentation was employed for kinetic assessment. A parallel equilibrium model bioconcentration strategy for 100-fold exposure range determined the internal body burden. Whole-body autoradiography and liquid scintillation techniques revealed the tissue distribution of PFOA. Remarkable levels of radioactivity were observed in target organs. The labeling of oocytes confirmed the maternal transfer of PFOA in zebrafish. In another study the effects of PFOA on reproduction and sexual development in zebrafish were evaluated. Reproductive traits like spawning, fecundity and fertilization were not altered in a short term experiment. The period of sexual differentiation in zebrafish was examined to determine the effects of PFOA on development, growth and gonad maturation. The development and growth of the zebrafish were not affected, but a trend in decreased survival in maternally exposed embryos was observed. The expression of Vtg mRNA level in the liver of PFOA-exposed male fish was not induced. Similarly, an inhibitory trend of PPARα mRNA expression in the liver of the highest PFOA exposed zebrafish was observed. The developmental toxicity ranking of PFAAs and kinetic assessment of PFOA with bioconcentration in zebrafish will provide an insight into risk assessment and replacement strategies of the compounds.
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