| 1. |
- Berg, Cecilia, 1967-, et al.
(författare)
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Xenopus tropicalis as a Test System for Developmental and Reproductive Toxicity
- 2009
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Ingår i: Journal of Toxicology and Environmental Health. - : Informa UK Limited. - 1528-7394 .- 1087-2620. ; 72:3-4, s. 219-225
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Tidskriftsartikel (refereegranskat)abstract
- The usefulness of Xenopus tropicalis as a model species to investigate endocrine disruption and developmental reproductive toxicity was assessed. In our test system tadpoles were exposed to test substances from shortly after hatching until metamorphosis, including the period of gonadal differentiation. Effects on the sex hormone and thyroid hormone axes were evidenced as skewed sex ratios, malformations of reproductive organs, altered cytochrome (CYP19) (aromatase) activity, and gene expression in gonads and brain, as well as changed thyroid histology and time to metamorphosis. Reproductive toxicity was evaluated at sexual maturity. Male-to-female sex reversal was implied at concentrations as low as 6 pM (1.8 ng/L) ethynylestradiol (EE2), which is comparable to EE2 levels observed in the environment. EE2-exposed males that were not sex reversed had significantly reduced fertility and a reduced amount of spermatozoa in testes compared with control males. This indicates that reproduction in wild frogs might be impaired by estrogenic environmental pollutants. Aromatase activity in brain and testes of adult frogs was not affected by larval EE2 exposure. Preliminary results indicate that exposure to the environmentally relevant pharmaceutical clotrimazole modulated aromatase activity in brain and gonads during sex differentiation, which warrants further investigation. The susceptibility to estrogen-induced sex reversal of X. tropicalis was comparable to that of other frog species and fish. Similarities between the reproductive effects in X. tropicalis and those reported in fish, birds, and mammals after developmental exposure to estrogens make X. tropicalis promising model for research on endocrine disruption and developmental reproductive toxicity.
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| 2. |
- Bergdahl, Ingvar A, et al.
(författare)
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Biomonitoring of lead exposure-alternatives to blood
- 2008
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Ingår i: Journal of Toxicology and Environmental Health. Part A: Current Issues. - : Informa UK Limited. - 1087-2620 .- 1528-7394. ; 71:18, s. 1235-1243
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Tidskriftsartikel (refereegranskat)abstract
- Lead (Pb) is one of the most important models for biomonitoring of exposure, with the blood Pb concentration as a predominant choice in practice and in epidemiology. In this article the alternatives for biomarkers to blood are reviewed. This overview focuses on a number of different qualities that are of importance in the evaluation of a biomarker's usefulness and performance. The qualities scrutinized included: (1) analytical accuracy and precision; (2) cost; (3) practical issues; (4) what is reflected by the biomarker; (5) relationship to exposure; and (6) relationship to effects. Data indicate that the best biomarker in some circumstances may be blood, but bone or teeth (for past exposures), feces (for current gastrointestinal exposure), or urine (for organic Pb) are sometimes more useful. A striking feature is that no generally accepted biomarker of bioavailable Pb exists, though plasma, bone, teeth, urine, and hair have all been discussed. For one of the most used applications of blood Pb, monitoring of lead workers' exposure, blood has important shortcomings in that it shows a poor response to changes in exposure at high levels. The alternative of plasma has not been sufficiently evaluated to be considered an alternative in occupational health services, although previous analytical problems are basically overcome. Possibly, urine deserves also more attention. Almost all biomarkers lack systematic data on variation within and between individuals.
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| 3. |
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| 4. |
- Fox, Glen A, et al.
(författare)
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Health of herring gulls (Larus argentatus) in relation to breeding location in the early 1990s : III. Effects on the bone tissue
- 2008
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Ingår i: Journal of Toxicology and Environmental Health. - : Informa UK Limited. - 1528-7394 .- 1087-2620. ; 71:21, s. 1448-1456
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Tidskriftsartikel (refereegranskat)abstract
- Health effects associated with the Great Lakes environment were assessed in adult herring gulls (Larus argentatus) in the early 1990s, including the size and quality of their bones. Femurs were excised from 140 individuals from 10 colonies distributed throughout the Great Lakes and 2 reference colonies in Lake Winnipeg (freshwater) and the Bay of Fundy (marine). Femurs of gulls from the Great Lakes differed from the freshwater or marine reference for 9 of 12 variables of size, composition, and strength assessed using peripheral quantitative computed tomography (pQCT) and biomechanical testing. Femurs of Great Lakes gulls were significantly smaller in length (-2.9%), periosteal circumference (-2.4%), and cross-sectional area (-5.4%) than freshwater reference birds. Femurs of the Great Lakes gulls had a lower significant cortical bone mineral content (-8.1%) and density (-2%) than the marine reference. A significant increase in the amount the bone could bend before it broke (+34%) and the energy required to break it (+44%) and a significant decrease (-16.3%) in stiffness during three-point biomechanical bending test were also detected in Great Lakes versus the freshwater gulls. These differences are indicative of impaired mineralization. When divided into high and low 2,3,7,8-tetrachlorodibenzo-p-dioxin toxicity equivalent (TCDD-TEQ) colonies, the amount the bone could bend before it broke and the energy required to break it were significantly higher in the high TEQ colonies, but not high polychlorinated biphenyl (PCB) colonies. Breeding location and dietary choices of Great Lakes herring gulls in the early 1990s resulted in modulations of physiological processes that affected the size, mineralization, and biomechanical properties of bone.
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| 5. |
- Hultman, Per, et al.
(författare)
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The effect of xenobiotic exposure on spontaneous autoimmunity in (SWR x SJL)F1 hybrid mice
- 2006
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Ingår i: Journal of Toxicology and Environmental Health. - : Informa UK Limited. - 1528-7394 .- 1087-2620. ; 69:6, s. 505-523
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Tidskriftsartikel (refereegranskat)abstract
- F1 hybrids of SWR (H-2q) and SJL (H-2s) mice spontaneously develop a lupuslike condition in an age-dependent manner, and these two H-2 haplotypes also confer susceptibility to induction of systemic autoimmunity by heavy metals such as mercury, silver, and gold with antifibrillarin antibodies (AFA) as marker. The aim of this study was to determine how the mixing of two susceptible genomes might influence expression of idiopathic and induced autoimmunity over a period of 14 mo of exposure to mercury and silver. Spontaneous autoimmunity first appeared as antinuclear antibodies (ANA) in females at 10 wk of age and in males at 10 mo of age, and was followed by development of anti-chromatin antibodies. Antibodies to double-stranded DNA developed in 60% of males and 20% of females. Thirty percent of males and 10% of females developed a coarsely speckled ANA pattern associated with high titers of anti-Sm antibodies. Glomerular immune complex (IC) deposits and a proliferative glomerulonephritis were seen at 17 mo of age. The F1 hybrids treated with metals showed no exaggeration of spontaneous autoimmunity. However, the metals suppressed the spontaneous development of anti-Sm and antichromatin antibodies. The metal-induced AFA, linked to the H-2s and H-2q haplotype, reached a maximum after 3-4 mo of treatment and then declined, 33% of the silver-treated hybrids finally became AFA-negative, despite continuous treatment. The decline in ANoA during metal treatment is contrary to the situation in metal-treated SJL mice. This indicates that dominant SWR background genes suppressed induction of certain autoimmune traits in the (SWR x SJL)F1 hybrid mice. Copyright© Taylor & Francis Group, LLC.
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| 6. |
- Johnsson, C, et al.
(författare)
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Impact of consumption of freshwater fish on mercury levels in hair, blood, urine, and alveolar air
- 2005
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Ingår i: Journal of Toxicology and Environmental Health. Part A: Current Issues. - : Informa UK Limited. - 1087-2620 .- 1528-7394. ; 68:2, s. 129-140
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Tidskriftsartikel (refereegranskat)abstract
- Human exposure to methylmercury occurs mainly via consumption of fish. The aim of the study was to investigate the influence of freshwater fish consumption on mercury levels in hair, blood, urine, and end-exhaled air. Twenty subjects without dental amalgam fillings were recruited from sport-fishing societies. They ranged in age from 61 to 87 yr. Six individuals ate freshwater fish at least once a week and were categorized as high consumers. Eight individuals were classified as medium consumers and ate freshwater fish at least once a month but less than once a week. Six individuals were categorized as low consumers and had not eaten freshwater fish in the past 3 mo. Among the high consumers, median concentrations of mercury were 8.6 mug/L in blood, 2.4 mug/g in hair, 10 mug/L in end-exhaled air, and 1.1 mug/g creatinine in urine. The relationship between freshwater fish consumption and mercury was significant in all biological media. The high-consumption group had much higher mercury levels in blood (9-fold), hair (7-fold), alveolar air (3-fold), and urine (15-fold) than the low-consumption group. The latter finding may be explained by demethylation of methylmercury in the body. The ratio between mercury concentration in blood and hair was 1:270. This implies that the typical blood-hair ratio of 1:250, specified by the World Health Organization (WHO) in 1990, is valid also for exposure to low amounts of methylmercury.
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| 7. |
- Kylin, Henrik
(författare)
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Comparing Water, Bovine Milk, and Indoor Residual Spraying as Possible Sources of DDTand Pyrethroid Residues in Breast Milk
- 2009
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Ingår i: Journal of Toxicology and Environmental Health, Part A: Current Issues. - : Informa UK Limited. - 1528-7394 .- 1087-2620. ; 72, s. 842-851
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Tidskriftsartikel (refereegranskat)abstract
- The presence of pollutants in human breast milk is of major concern, especially in malaria control areas where 1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane (DDT) is currently used as indoor residual spray (IRS). The levels of DDT and pyrethroids (PYR) were determined in breast milk, bovine milk, and drinking water from northern KwaZulu-Natal, South Africa. Both reference and exposed mothers used the same market food, but the DDT levels in the exposed mothers (mean sigma DDT 10 g/g milk fat [mf]) were much higher than for the reference mothers (mean sigma DDT 1.3 g/g milk fat). This difference in residue levels indicates uptake from IRS-applied DDT, most likely via air and skin contact, and excludes food as the main source of pollutants. DDT levels in bovine milk (mean sigma DDT 0.15 g/g mf) from the exposed area were less than levels in breast milk from the reference area, and lower than the 20 g/L maximum residue limit (MRL) set by the Food and Agriculture Organization (FAO). Mean sigma DDT in water was 0.0065 g/L, much lower then the WHO limit of the sum of all metabolites in drinking water of 1 g/L, and therefore highly unlikely to have contributed to any extent toward levels in breast milk. Permethrin in breast milk (mean 1.1-1.6 g/g milk fat) was probably derived from home garden and indoor use, while the other PYR (cypermethrin and cyfluthrin) at lower concentrations were probably derived from food and agricultural exposure. It is postulated that a better understanding of the indoor dynamics of DDT and other insecticides, through a concept of Total Homestead Environment Approach (THEA), is crucial for investigating options of reducing human exposure and uptake under malaria control conditions.
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| 8. |
- Lundberg, Rebecca, et al.
(författare)
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Effects of short-term exposure to the DDT metabolite p,p'-DDE on bone tissue in male common frog (Rana temporaria)
- 2007
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Ingår i: Journal of Toxicology and Environmental Health. - : Informa UK Limited. - 1528-7394 .- 1087-2620. ; 70:7, s. 614-619
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Tidskriftsartikel (refereegranskat)abstract
- Experimental studies as well as studies in free-ranging animals have shown that endocrine-disrupting chemicals (EDCs) impair bone tissue composition and strength. The aim of the present study was to expand our studies on bone tissue in a new group of animals by investigating whether bone tissue in frogs is an additional potential target of EDCs. Adult male European common frogs (Rana temporaria) were divided into 5 groups (n = 20) and injected (sc, single injection) with p,p'-DDE, a total dose of 0.01, 0.1, 1, or 10 mg of p,p'-DDE/kg body weight, respectively. A control group was treated with the vehicle (corn oil). Two weeks after injection the frogs were euthanized and samples taken. The diaphysis of the excised left femur was scanned using peripheral quantitative computed tomography (pQCT) and cortical variables, such as cortical bone mineral density (BMD), cortical cross-sectional area (CSA), and periosteal circumference, were determined. In addition, biomechanical three-point bending of the bones was conducted, with the load being applied to the same point as where the pQCT measurement was performed. The results from the pQCT measurements show that bone tissue in male frogs exposed to p,p'-DDE is negatively affected. A significant decrease in cortical BMD at the diaphysis was observed in frogs exposed to 1 mg p,p'-DDE. However, the biomechanical testing of the bones showed no significant differences between exposed and control group. Although this is the only study performed to date examining the possible relationships between EDCs and negative effects on frog bones, it supports both previous experimental findings in rodents and findings in free-ranging animals.
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| 10. |
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