Worldwide Fish Stocks Facing Extinction Oct 4, 2004 20:47:44 GMT -5
Post by Big Bunny on Oct 4, 2004 20:47:44 GMT -5
The Environment Agency denies that there is any danger. Water UK, which represents the water companies, says that no hormone-disrupting chemical has ever been detected in British drinking water, and that fish placed in the water to test it did not become feminised.
But some scientists say that the chemicals may not have been detected, because there is no routine testing for them in drinking water, and because the equipment used in Britain is not sensitive enough.
Research at the University of Ulm, in West Germany, using more sophisticated techniques, found small amounts in four out of every 10 samples tested. And environmentalists fear that effects in people may occur over much longer periods than those used to test the fish.
Dr Susan Jobling of Brunel University, who led the research, says: "Unlike in fish, it is going to take 20 years to see if my children have been affected by developmental exposure to this same cocktail of chemicals."
The male ERKO mice are infertile and upon histological examination they show seminiferous tubular swelling and loss of spermatogenesis. The sperm made in the testes of these animals are non-functional. The testicular LH and FSH receptors are up-regulated, but gonadotropin levels are normal. ERb persists in the ERKO mice, showing that there is no interrelationship between expression of the two ER types.
Seminal vesicle and epididymis weights of the mice are normal, indicating that androgen action is not compromised. The hypothalamic-pituitary level appears to adapt to the lack of estrogen action by maintaining or developing responsiveness to negative feedback effect to DHT, which is not seen in normal male mice. Hence the neuroendocrine regulation of gonadotropin secretion in the ERKO mice is reprogrammed.
As regards sexual behavior, the ERKO mice have normal amount of mountings but lower number of intromissions and ejaculations. The level of aggression of the ERKO males is also suppressed. Moreover, the bone density of the ERKO mice is suppressed.
(01/29/2002) Study finds that men who eat Great Lakes fish contaminated with toxic, hormone-disrupting chemicals such as PCBs father a disproportionately high number of boys. Men who eat fish from the Great Lakes, which are laced with such toxic industrial chemicals as PCBs, conceive a disproportionately high number of sons, according to new research.
The strange effect that PCBs seem to have on sex ratios is poorly understood, but is too significant to pass off as mere coincidence, said Wilfried Karmaus, a professor of epidemiology at the University of Michigan. He suggested the effect might be due to a disruption of hormone levels in the male reproductive system, which has been documented in other, more severe cases of PCB exposure.
Karmaus followed nearly 400 families who regularly ate various fish - walleye, carp, salmon, trout, among others - they caught in Lake Michigan. Of the 208 children born to the men with the highest PCB content in their blood, 57% of them were boys. This figure is statistically far higher than the worldwide average sex ratio in which about 52% of newborns are male.