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Endocrine Disruptors

3. Do EDCs affect wildlife?

  • 3.1 What are the most illustrative examples of effects on wildlife?
  • 3.2 How reliable is the evidence in wildlife?

The source document for this Digest states:

Several field and laboratory studies have shown that exposure to certain EDCs has contributed to adverse effects in some wildlife species and populations. These effects vary from subtle changes in the physiology and sexual behavior of species to permanently altered sexual differentiation. Most of the data comes from Europe and North America. Aquatic species (at the top of the food chain) are most affected, but effects have also been observed in terrestrial species. Some adverse effects observed in certain species are likely to be endocrine mediated, but in most cases, the causal link between exposure and endocrine disruption is unclear.

Source & ©: IPCS "Global Assessment of the state-of-the-science of Endocrine disruptors "
 Executive Summary (Chapter 1) page 2 section 1.4

For further details, see IPCS  Chapter 4, section 4.7, page 49

3.1 What are the most illustrative examples of effects on wildlife?

The source document for this Digest states:

Examples include the following see IPCS assessment, chap 7.

Source & ©: IPCS "Global Assessment of the state-of-the-science of Endocrine disruptors "
 Executive Summary (Chapter 1) page 2 section 1.4

3.1.1 Mammals

The source document for this Digest states:

exposure to organochlorines (PCBs, DDE) has been shown to adversely impact the reproductive and immune function in Baltic seals, resulting in marked population declines. These seals exhibit a compromised endocrine system, but precise mechanisms of action remain unclear.

Source & ©: IPCS"Global Assessment of the state-of-the-science of Endocrine disruptors "
 Executive Summary (Chapter 1) page 2 section 1.4

For more info on the criteria used for the selection of these most illustrative examples, see IPCS  Chapter 7, section 7.1-7.3, page 123.

For further details on Baltic seals and other marine mammals, see IPCS  Chapter 7, section 7.5.6, page 127 and  Chapter 4, section 4.1.2.2, page 34.

For details on: See IPCS assessment:
Basic facts about mammals  Chapter 4, section
4.1.1, page 34
Effects in mustelids including mink, Canadian otter, European otter and Swedish otter  Chapter 4, section
4.1.2.1, page 34
Reproductive effects in feral rodents including white-footed mice, meadow voles and cotton rats  Chapter 4, section
4.1.2.3, page 35
Inconclusive effects in Florida panthers, black/brown bears, polar bears and beluga whales  Chapter 4, section
4.1.2.4, page 35

3.1.2 Birds

The source document for this Digest states:

Eggshell thinning and altered gonadal development have been observed in birds of prey exposed to DDT, resulting in severe population declines. A syndrome of embryonic abnormalities (known as GLEMEDS) has been observed in fish-eating birds and can be directly related to PCB exposure, but the precise linkage to endocrine function is uncertain.

Source & ©: IPCS"Global Assessment of the state-of-the-science of Endocrine disruptors "
 Executive Summary (Chapter 1) page 2 section 1.4

For further details on eggshell thinning and deformities observed in birds, see IPCS Chapter 7, section 7.5.7, 7.5.8, page 127 and  Chapter 4, section 4.2.2.4, 4.2.2.5, page 38

For details on: See IPCS assessment:
Basic facts about birds  Chapter 4, section
4.2.1, page 36
Where high levels of contamination may have caused alteration of behavior in gulls, doves, Japanese quails and zebra finches  Chapter 4, section
4.2.2.1, page 36
Pesticides that may be responsible for abnormal reproductive morphology in gulls and terns  Chapter 4, section
4.2.2.2, page 37
Possible adverse effects that may cause the lowering of the male population and female-female pairings in gulls  Chapter 4, section
4.2.2.3, page 37

3.1.3 Reptiles

The source document for this Digest states:

A presumed pesticide spill in Lake Apopka (Florida, USA) provides a well publicized example of potential EDC effects on population decline in alligators. A variety of gonadal and developmental abnormalities were observed that have been attributed to high levels of various organochlorine contaminants that disrupt endocrine homeostasis. Several hypotheses have been proposed to explain the contaminant-induced endocrine disruption, but the precise cause(s) is not known.

Source & ©: IPCS "Global Assessment of the state-of-the-science of Endocrine disruptors "  Executive Summary (Chapter 1) page 2 section 1.4

For details on: See IPCS assessment:
Basic facts about reptiles  Chapter 4, section
4.3.1, page 39
Developmental abnormalities in the Great Lakes snapping turtles, which may be due to chlorinated hydrocarbons  Chapter 4, section
4.3.2.2, page 40

3.1.4 Amphibians

The source document for this Digest states:

Population declines in amphibians have been observed in both pristine and polluted habitats worldwide. Currently, the data are insufficient to implicate EDCs as causative agents.

Source & ©: IPCS "Global Assessment of the state-of-the-science of Endocrine disruptors "
 Executive Summary (Chapter 1)page 2 section 1.4

For details on: See IPCS assessment:
Basic facts about amphibians  Chapter 4, section
4.4.1, page 40
Studies showing that pesticides might be an important factor in the decline of frog populations  Chapter 4, section
4.4.2.1, page 41
Factors, such as environmental contaminants, trematodes and ultraviolet light that may be responsible for deformities in the frogs Chapter 7, section
7.4.2, page 125 and  Chapter 4, section
4.4.2.2, page 41

3.1.5 Fish

The source document for this Digest states:

There is extensive evidence that chemical constituents present in pulp and paper mill effluents and sewage treatment effluents can affect reproductive endocrine function and contribute to alteration in reproductive development. A variety of mechanisms (e.g., hormone–r eceptor interactions, interference with sex steroid biosynthesis, altered pituitary function) are involved, but precise modes of action or the causative chemicals are still poorly understood.

Source & ©: IPCS "Global Assessment of the state-of-the-science of Endocrine disruptors "
 Executive Summary (Chapter 1) page 2 section 1.4

For details on: See IPCS assessment:
Basic facts about fish  Chapter 4, section
4.5.1, page 42
EDCs in sewage treatment discharges and pulp and paper mill effluents that may alter reproductive development and cause reproductive abnormalities in fish Chapter 7, sections
7.5.11, 7.5.12, pages 128, 129 and  Chapter 4, sections
4.5.2.2.1, 4.5.2.2.2, pages 43, 44
EDCs that induce vitellogenesis (normally seen only in females) in juvenile and adult males of several fish species Chapter 7, section
7.5.10, page 128 and  Chapter 4, section
4.5.2.1, page 42
Reduced reproductive success in flatfish that may be caused by PAHs, DDT and PCBs  Chapter 4, section
4.5.2.2.3, page 45
Reduced reproductive success in perch, herring, cod, European flounder, lake trout and arctic char that might be due to EDCs  Chapter 4, section
4.5.2.2.4, page 45
EDCs (phytoestrogens and BKME) that may alter sex steroid levels in fish  Chapter 4, section
4.5.2.3, page 45
Altered adrenal physiology in fish exposed to metal contaminants  Chapter 4, section
4.5.2.4, page 46
EDCs that may be responsible for the blue-sac disease in lake trout and early-life-stage mortality in fish  Chapter 4, section
4.5.2.4, page 46
Unknown substances that may be responsible for thyroid dysfunction in Salmonids in the Great Lakes region  Chapter 4, section
4.5.2.6, page 47

3.1.6 Invertebrates

The source document for this Digest states:

exposure of marine gastropods to TBT (a biocide used in antifouling paints) provides the clearest example in invertebrates of an endocrine-mediated adverse effect caused by exposure to an environmental contaminant. Masculinization of marine gastropods exposed to TBT has resulted in worldwide declines of gastropods. The endocrine mechanism probably involves elevated androgen levels possibly through altered aromatase activity.

Source & ©: IPCS "Global Assessment of the state-of-the-science of Endocrine disruptors "
 Executive Summary (Chapter 1) page 2 section 1.4

For details on: See IPCS assessment:
Basic facts about invertebrates  Chapter 4, section
4.6.1, page 47
Environmental chemicals that interfer with the process of molting  Chapter 4, section
4.6.2.2.1, page 49
Environmental chemicals may cause disruption of juvenile hormone regulated processes in crustaceans  Chapter 4, section
4.6.2.2.2, page 49
EDCs that affect the insect endocrine system, causing molting disturbances and deformities  Chapter 4, section
4.6.2.3, page 49

3.2 How reliable is the evidence in wildlife?

The source document for this Digest states:

Studies in wildlife have been proposed as ‘sentinels’ of human exposure to EDCs. However, given the diversity of wildlife, caution must be taken in extrapolating the responses to EDCs, as research has focused primarily on only a few species of wildlife. Also, potential effects of EDCs on wildlife tend to focus on the individual, whereas ecological risk assessments focus on populations and communities. The significance of disturbances in reproductive output and viability of offspring on populations is difficult to quantify. Overall, the current scientific knowledge provides evidence that certain effects observed in wildlife can be attributed to chemicals that function as EDCs. However, in most cases, the evidence of a causal link is weak, and most effects have been observed in areas where chemical contamination is high.

Source & ©: IPCS "Global Assessment of the state-of-the-science of Endocrine disruptors "
 Executive Summary (Chapter 1) page 2 section 1.4

For further details see IPCS Chapter 4, section 4.7, page 49.


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