Endocrine disruption in biota
The endocrine (hormone) system - the complicated setup/net of glands, hormones and receptors being responsible for the development of gender characteristics, reproductive system, brain and nervous system, furthermore for the regulation of metabolic processes during entire life time - is vulnerable to environmental contamination.
A variety of man-made chemicals, such as agrochemicals, pharmaceuticals, flame retardants, detergents, plasticizers, personal care products might inadvertently interfere with the endocrine system of humans and wildlife in different ways. Some chemicals might block or stimulate the effects of hormones and might lead to developmental and reproductive disorders.
Identification of emerging endocrine disrupting chemicals (EDCs)
There are still many scientific questions to be answered on the field of endocrine disruption, especially about the consequences of this type of contamination. The best way to understand and study the fate, transport, complicated exposure routes and mode of actions of the endocrine disrupting compounds (EDCs) in the environment is to apply interdisciplinary approaches – combining chemistry, physics, biology and toxicology –. A promising integrated tool to identify EDCs is the so called Effect-Directed Analysis (EDA). The combination of fractionation techniques, analytical chemistry and biotesting results in detection of environmental pollutants (e.g. EDCs) in complex environmental matrices. The samples that show affinity to interfere with the hormone system in the bioassay are further fractionated (classified based on chemical properties) until a number of chemical suspects can recognize which are responsible for the measured effect in the bioassay. EDA can apply to any type of environmental sample as example water, sediment, air, soil and biological materials.
An ongoing PhD research investigates newly emerging EDCs accumulated in aquatic biota samples with the aid of EDA at IVM by the PhD candidate, Eszter Simon. Her main focus is assessing androgen- (male hormone) and thyroid hormone-disrupting chemicals in biota that are less studied toxic endpoints in endocrine disruption research. The project was funded by the Marie Curie Research Training Network (RTN, EC Sixth Framework Program) and entitled “Keybioeffects” studying the cause-effects relations of key pollutants on the European rivers diversity.
The first and very critical step in EDA for identification of EDCs is to extract the compounds of interest from the given sample matrix. This requires nondestructive analytical techniques that allow the separation of EDCs from fatty tissues, natural hormones, proteins, that some of these compounds might bind to. Major part of Eszter’s PhD was dedicated to develop such gender sample preparation methods to various biota samples (fish tissues, fish whole body homogenate, and blood plasma) that enables getting to the following steps of EDA: 1) testing these extracts in bioassays to confirm their affinity interfering with the hormone system 2) carrying out chemical analysis on the extracts in order to assess the suspects/possible candidates for endocrine disruption.
Despite the difficulties to extract biota samples, the biggest advantage of this type of sample matrix that biota can also be used for monitoring purposes and for providing information on biologically relevant concentrations of aquatic pollutants. Another advantage of analyzing biota is that bioavailability, bioaccumulation and possible metabolization of the compounds are also included.
Contribution of this piece of work to endocrine disruption research
The main objective of “Keybioeffects”, on which program 12 PhDs and 6 post-doctorate researchers were working together to support the achievement of the Water Framework Directive (WFD): the acceptable water quality of the European Rivers by 2015. They try to transfer knowledge to water agencies on new toxicants and their life route and possible effects on European river ecosystems.
Eszter’s research will contribute to improving different aspects of water pollution by providing recommendations for chemical analysis (sample preparation techniques, procedures for identification of new compounds), for broadening the scale of routinely monitored priority pollutants and for toxicity testing (investigating less studied toxic endpoints, such as androgen and thyroid hormone disruption).
Applicability of the research: Polar bear plasma screening and food web study
Within the collaboration with the Norwegian University of Science and Technology (NTNU, Department of Biology, Trondheim), one of the developed sample preparation techniques was successfully applied to 30 polar bear plasma samples. The plasma extracts containing environmental chemicals were then tested for their ability to disrupt the thyroid hormone system. The identification of the thyroid hormone-disrupting compounds – that caused activity in the samples – is currently conducted by high accuracy mass spectrometry.
Furthermore passive samplers placed out and collected in the Netherlands within another project – DiPol, the Impact of Climate Change on the quality of urban and coastal waters and - are also currently analyzed by EDA among other toxic endpoints for thyroid hormone disruption. The study aims to investigate bioavailable thyroid hormone-disrupting compounds and compare to thyroid hormone-disrupting compounds found in samples of a food chain from the same location.
For further information:
Simon E., Lamoree M.H., Hamers T., Weiss J., Balaam J., De Boer J., Leonards P.E.G. Testing endocrine disruption in biota samples: a method to remove interfering lipids and natural hormones 2010Env. Sci. Technol. 44(21):8322-9 DOI: 10.1021/es101912z
Weiss J.M., Simon E., Stroomberg G.J., de Boer R., de Boer J., van der Linden S.C., Leonards P.E.G., Lamoree M.H. Integrated identification strategy for unknown pollutants on an LTQ-Orbitrap: androgen disrupting compounds identified using effect-directed analysis 2011 Anal. Bioanal. Chem. 400:3141-3149 DOI: 10.1007/s00216-011-4939-x
Simon E., Bytingsvik J., Jonker W., Leonards P.E.G., De Boer J., Jenssen B.M., Lie E., Aars J., Hamers T., Lamoree M.H. Broad-range sample preparation method to determine thyroid hormone-disrupting compounds in blood plasma 2011Environ.Sci. Technol.DOI: 10.1021/es2016389
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