Impairments of Endocrine Functions: Causes and Consequences - Ecological Biomarkers: Indicators of Ecotoxicological Effects - page 207

Population modeling

Individual fitness

Life-traits Behavior

- Motor activity
- Diet
- Sexual behavior

- Growth
- Development
- Reproduction

Subindividual markers of endocrine disruption

FIGURE 8.5
Simplified representation of concept of an adverse outcome pathway applied to effects of EDCs on steroid,
thyroid, and molt hormones. (After Coulaud, R. 2012. Modélisation et changement d'échelles pour l'évaluation
écotoxicologique: application à deux macroinvertébrés aquatiques, Gammarus fossarum (Crustacé amphipode) et
Potamopyrgus antipodarum (Mollusque Gastéropode) Thesis Lyon University. With permission.)

The status of methods for estrogen-specific effects monitoring has been recently
reviewed (OSPAR agreement 2008-2009). VTG and gonadal intersex measurements have
been intercalibrated in the framework of BEQUALM (Biological Effects Quality Assurance
in Monitoring Programmes in the European Community) and are recommended for use
by the International Council for the Exploration of the Sea.
Endocrine disruptors affect biological processes linked to reproduction and devel-
opment. So, it is evident that, in order to distinguish between natural stress and stress
induced by EDCs, it is indispensable to have a good knowledge of the normal function-
ing of endocrine metabolism depending on phylogeny, sex, and development status. For
wildlife, and particularly for invertebrates, only relatively sparse knowledge of endocrine
mechanisms and relevant biomarkers is yet available to predict and to survey the impact
of complex mixtures of endocrine disrupters in the field.
Moreover, in addition to biological factors, extrinsic factors can also influence reproduc-
tion and development, such as temperature and food availability. Seasonality not only
affects temperature (e.g., Sieratowicz et al. 2011) but also the production of estrogens and
their conjugates (Kumar et al. 2011), and hypoxia has been recently recognized as acting
like an endocrine disruptor (Murphy et al. 2009; Wu 2009; Thomas and Rahman 2012).
With the aim of using biomarkers to investigate the presence and effect of EDCs in the
environment, it is necessary to evaluate the influence of all such confounding factors.

References
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Ahmed, O.M. et al. 2010. Effects of experimentally induced maternal hypothyroidism and hyper-
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neurotransmitters and adenosinergic system interactions. Int. J. Dev. Neurosci. 28:437-54.