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New
scientific results on
impacts of endocrine disruptors on wildlife |
| Low doses of nonylphenol have profoundly adverse effects on oysters. A single exposure during larval development to an environmentally-relevant dose of nonylphenol causes disruption of sexual development, and also lowers survival of offspring in the next generation. Exposed larvae are much more likely to develop as hermaphrodites, and the sex ratio is altered, with more females than expected. According to the scientists who conducted the research, exposure "may result in severe consequences, not only for natural populations but also for commercial hatcheries situated in areas where nonylphenol is present in the water. More... A combined lab and field study of the leopard frog, Rana pipiens, implicates atrazine in widespread feminization of males during tadpole development and metamorphosis. The lab studies confirmed earlier findings from a different amphibian, the African clawed toad, that extremely low levels of atrazine causes significant gonadal abnormalities in male frogs. The field studies demonstrate widespread abnormalities in wild populations of the frog and link them to the geography of atrazine use. More... 23 July 2002. An elegant series of field and laboratory experiments with wood frogs reveals that pesticides (atrazine, malathion and esfenvalerate) at very low levels damage the frogs' immune system and thereby impair their ability to resist infection by parasites. The parasite cysts imbedded in the growing tadpole then cause limb deformities. It thus appears that what had thought to be two competing ideas about why deformities have become so common—parasites vs. pesticides— are actually working in concert together. More... 15 April 2002 Research by scientists at the University of California, Berkeley, reveals that the most abundantly used herbicide in the world, atrazine, disrupts the development of frogs at extraordinarily low levels of exposure. Over 15% of males of the classic "laboratory rat" of the frog world, Xenopus laevus, developed hermaphroditic reproductive tracts when exposed, during development, to 0.1 parts per billion atrazine. The researcher team, led by Dr. Tyrone Hayes,also noted demasculinization of secondary sexual characteristics and alterations in serum hormone levels. More... 23 June 2001. A team of scientists from Northern Arizona University reports that endosulfan at very low levels disrupts reproductive communication between male and female salamanders by altering the development of glands involved in pheremone production. Exposed females of the red-spotted newt Notophthalmus viridescens, a North American salamander, then suffer lowered mating success. Contaminant levels sufficient to cause an effect -- 5 parts per billion-- are far beneath water quality standards mandated by the US EPA for this commonly used pesticide. More... 16 February 2001. New research on tadpoles of the North American gray treefrog reveals an unexpected interaction between a common pesticide, carbaryl, and stress induced in the tadpoles by predators. Without the predator-induced stress, short-term exposure to low levels of carbaryl had no effect on survival. Longer exposure increased mortality. By far the highest mortality, however, was caused by exposure to carbaryl while in the presence of a predator. Up to 97% of tadpoles died under these conditions. [The experiments were conducted in a way that the tadpoles could sense the predator's presence but the predator could not reach them.] These results indicate that frogs are far more sensitive to pesticides in real-world conditions than traditional toxicity testing will ever reveal. More...
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15 December 2000. Writing in Environmental Health Perspectives, the journal of the National Institute of Environmental Health Sciences, scientists report widespread feminization of an endangered fish, the chinook salmon, breeding in central Washington on the Hanford Reach of the Columbia River. Of females sampled on spawning grounds, 84% are chromosomal males. Two plausible causes: higher water temperatures or endocrine disruption. More...
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| 18
September 2000. In
a news
story covered by ENN, The Qikiqtaaluk Wildlife Board and the World
Wildlife Fund report that a new survey reveals the impact of pollution
on arctic wildlife. Hunters and elders from four Canadian arctic
villages participated in the survey. Among them they have a combined
hunting experience of about 800 years. "Hunters and elders from
every community talked about abnormalities in at least one of the
species they harvest regularly - caribou, seal, walrus, beluga, narwhal
and polar bear. " "Almost half of the survey's participants
said they see increasing abnormalities."
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| 6
September 2000. The BBC reports that endocrine disruption of fish
is widespread in northern Europe, with confirmations obtained
from 5 of 7 countries examined. Up to 100% of fish are affected in
some river systems. A combination of industrial compounds and human
urinary metabolites (from drugs) appear to be the cause. More...
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| The
BBC reports that one percent of polar bears on the Arctic island or
Svarlbard are hermaphroditic, and scientists studying this unnatural
phenomenon believe it is due to endocrine disrupting chemicals. More...
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| Pacific
Killer Whales Orcinus orca are heavily contaminated by PCBs,
particularly those individuals that specialize dietarily upon other
marine mammals. More...
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| 4
July 2000. Researchers report that whale and dolphin meat sold in
Japan for human consumption is contaminated heavily by dioxin. More...
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| Exposure in the egg to DDT can cause complete sex reversal in a species of fish. The male-to-female reversal in Japanese medaka Oryzias latipes can be complete, permanent, and functional after a onetime embryonic exposure to the contaminant. Exposed fish that carry chromosomes typical for males of this species have fully functional oviducts and bear fertile offspring. More... |
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Arochlor 1242, chlordane and trans-nonachlor alter sexual differentiation during embryonic development in turtles, leading to changes in the ratio of males:females hatched. These compounds also alter circulating hormone levels of hatchling turtles exposed as embryos in the egg. More... |
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Salmon transport nutrients and pollutants upstream during their migrations, causing accumulation of persistent bioaccumulative contaminants in remote lakes. More... |
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Atlantic
Salmon are now virtually extinct in most of their original range
in New England and eastern Canada. A
major contributor to their decline now appears to be the disruption
of hormonal control of their ability to adjust to salt water during
migration to the sea. Surprisingly, the impact is from a compound,
nonylphenol, used as an "inert" surfactant in a pesticide,
not the component of the pesticide thought to be biologically active.
More... |
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Dioxin in the sediments and waters of the Great Lakes induces very high mortality in Lake Trout fry (immediately post-hatching). This now appears to be an important contributor to the cataclysmic decline of that commercially important fishery. More... |
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Frog deformities--extra legs, misplaced eyes, missing limbs, mishapen extremeties--are being detected at levels drastically above any rate which might plausibly be thought to be natural. Several factors, including contamination, appears to be contributing to this phenomenon. The importance of different factors appears to vary from one place to another. More...
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Two established reproductive toxins in people, dibromochloropropane (DBCP) and ethylene dibromide (EDB), may have contributed to population declines in American Alligators. More... |
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Types of animals throughout the animal kingdom use hormones or hormone-like signals to guide development from embryo to adulthood. Most of the attention has been focused on vertebrate species--mammals, birds, fish, amphibians, reptiles. But most of the animal kingdom is invertebrate. New studies reveal invertebrate species' vulnerability to endocrine disruption. More...
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