Lennart Balk

Publications (78) View all

• Source

  Available from: Lennart Balk

  Dataset: Investigation of the biological effects of 2-cycle outboard engines' exhaust on fish

  U. Tjärnlund, G. Ericson, E. Lindesjöö, I. Petterson, L. Balk
• Source

  Available from: Lennart Balk

  Dataset: Tjärnlund et al 1995

  U. Tjärnlund, G. Ericson, E. Lindesjöö, I. Petterson, L. Balk
• Conference Proceeding: Biotoxicity testing and chemical analysis at a munitions dumping area in the Stockholm archipelago (Baltic Sea) revealed low toxicity and low concentrations of lipophilic pollutants

  T. Hansson, G. Akerman, U. Tjamlund, H. Sundberg, K. Grander, Y. Zebuhr, A. Caiti, L. Balk
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  ABSTRACT: The potential toxicity of lipophilic pollutants in surficial sediment from a munitions dumping area in the Stockholm archipelago (Sweden, Baltic Sea) was investigated by nanoinjection of sediment extracts into newly fertilized rainbow trout (Oncorhynchus mykiss) eggs. Mortality and several types of abnormal development of the larvae were analyzed as measures of biotoxicity. Biochemical variables, such as ethoxyresorufin O-deethylase (EROD) and ethoxycoumarin O-deethylase (ECOD) induction and acetylcholine esterase (AChE) inhibition were analyzed as measures of sublethal toxicity. Chemical analysis of selected poly chlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in the sediments was also performed. Neither embryo mortality, larval mortality, nor deformities showed any increase in the sites of the dumping area compared to the neighboring sites. Neither were there any important differences between the sites in the dumping area and the neighboring sites for the variables length, haemorrhages, heart sac oedema or yolk sac oedema, vertebral deformities, or other morphological disorders. The response was low also for the sub-lethal biochemical variables EROD activity, ECOD activity and AChE activity. The conclusion was that no measurable lipophilic toxicants were released from the dumped munitions. It should be emphasized, though, that the lack of toxicity is shown only for this relatively small dumping area and that the results cannot be extrapolated to other (larger) dumping areas without reservations. The potency of the sediment extracts from the investigated area to induce EROD and ECOD activities, can be explained by a background level of pollution, illustrated by the presence of a number of PCBs and PAHs.
  Oceans 2005 - Europe; 07/2005
• Article: Evidence for endocrine disruption in perch (Perca fluviatilis) and roach (Rutilus rutilus) in a remote Swedish lake in the vicinity of a public refuse dump.

  E Noaksson, U Tjärnlund, A T Bosveld, L Balk
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  ABSTRACT: A two-year study on perch (Perca fluviatilis) in Lake Molnbyggen, Sweden, located in a pristine area but with a public refuse dump in the vicinity, has been conducted. The mechanistic approach through a set of biomarkers during the first year included age, condition, somatic growth, liver, gonad, and spleen weights, and a number of other physiological variables, in addition to ethoxyresorufin O-deethylase, glutathione-S-transferase, glutathione reductase, catalase, and the formation of DNA adducts in the liver. Perch from the uncontaminated Lake Djursjön, located in a neighboring drainage area, were used as reference fish. The most pronounced effect was a 80% reduction in the gonadosomatic index (GSI) for females and a corresponding 36% reduction in males. Fin erosion and shallow open sores were also frequently observed. Biomarkers and later chemical analysis employed indicated that exposure to well-known environmental pollutants was low, suggesting that less well-known antrophogenic substances are responsible for the effects observed in perch from Lake Molnbyggen. During the second year, roach (Rutilus rutilus) of both sexes were also included in this study. In addition, aromatase (P450arom) activity in the brain and testosterone and 17beta-estradiol levels in blood plasma were analyzed. Only one-fourth of the female perch were found to be sexually mature, which was associated with decreased GSI, lower P450arom activity, and reduced circulating levels of steroids. The reproductive disorders observed indicates disturbed endocrine function(s), arresting the majority of the female perch in a sexually nonreproducible immature stage. This novel study is the first to report evidence for endocrine disruption in wild populations of fish living in a lake exposed to leakage water from a public refuse dump.
  Toxicology and Applied Pharmacology 08/2001; 174(2):160-76. · 4.45 Impact Factor
• Article: PAH metabolites in bile, cytochrome P4501A and DNA adducts as environmental risk parameters for chronic oil exposure: a laboratory experiment with Atlantic cod.

  E Aas, T Baussant, L Balk, B Liewenborg, O K Andersen
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  ABSTRACT: In order to perform environmental risk assessments with regard to oil contamination in the sea, it is important to obtain knowledge about threshold levels for possible adverse effects in marine organisms. With this objective in mind, selected biomarkers were studied in Atlantic cod (Gadus morhua) chronically exposed to mechanically dispersed crude oil. The fish were exposed for 30 days in a continuous flow system to nominal concentrations of 0.06, 0.25 and 1 ppm North Sea crude oil. Fish were sampled five times during the exposure period. In addition, the 1 ppm group and the control group were sampled 1 week after the end of exposure. Polyaromatic hydrocarbon (PAH) concentrations in the seawater were analysed regularly by direct fluorescence and, at one occasion, by gas chromatography with mass spectrographic detection (GC/MS) measurements. Liver samples were analysed for parent PAH levels by means of GC/MS measurements, and PAH metabolites in bile were analysed by means of fixed wavelength fluorescence. Cytochrome P450 induction in liver was estimated by ethoxyresorufin-O-deethylase (EROD) activity, and hepatic DNA adducts were analysed by the 32P-postlabelling assay. The parent PAH concentrations in liver showed peak levels 3 days after the start of exposure, followed by a reduction towards the end of the experiment. In contrast, the PAH metabolites in bile and EROD activity showed generally increasing levels throughout the whole exposure period, indicating an increased biotransformation efficiency. The level of DNA adducts in the 1 ppm group showed a stable increase during the entire exposure period. Only a slight, non-significant decrease in DNA adduct levels was observed after 7 days of recovery in clean water. Exposure-dependent responses were observed for all three biomarkers. The lowest nominal concentration of dispersed oil in water, 0.06 ppm, corresponded to a measured total PAH concentration in the water of 0.3 ppb. Atlantic cod exposed to this concentration showed increased levels of PAH metabolites in bile and a slight induction of CYP1A, as well as formation of DNA adducts when compared with control fish. Particularly noteworthy is the detection of DNA adducts at such a low exposure concentration of oil in water, which, to our knowledge, is a novel finding. These dose-response data may serve as useful contributions when assessing environmental risk with regard to marine oil pollution.
  Aquatic Toxicology 01/2001; 51(2):241-58. · 3.76 Impact Factor