Exposure to environmental toxins may be responsible for female infertility. In particular substances known as endocrine disrupting chemicals (EDCs) may play a crucial role. These environmental toxins are either synthetic chemicals used in industry, agriculture or pharmacy, or natural chemicals found in food. Thus, exposure to EDCs can occur at different ways, e.g. drinking of contaminated water, breathing of contaminated air, or simple food intake. Despite most EDCs exhibit a long half-life, continuous accumulation of endocrine active substances will occur globally. In addition, low water-solubility and extremely high lipid-solubility promoted the accumulation within the human organism.

Consequently, EDCs may harm human health. It is known that EDCs lead to the disruption of the physiological system and that endocrine active substances interfere with the endocrine homeostasis. Moreover, EDCs alter organs that regulate male and female hormonal regulation crucial for reproduction fitness. Sterility and infertility, dysfunctional ovaries and an increased risk of abortions are discussed as critical consequences of EDC exposure.

It was shown that some endocrine active substances are present in the follicle fluid of women with unfilled pregnancy. Oocytes from follicles with an increased concentration of environmental toxins exhibit a reduced developmental potential. Additionally, women with an increased level of the EDC Bisphenol A tend to exhibit an increased risk of aborts.

Nonylphenol (NP) belongs to the class of endocrine active substances and are of special importance due to their high longevity and toxic characteristics. Nonylphenol is a multi-compound mixture that becomes generated as a by-product after degeneration of nonylphenol-ethoxylates (NPE) due to biological wastewater treatment. NPE are components of several cleaning agents, emulsifiers, dispersing agents and pesticides. NP is a mixture that consists mainly of para-substituted mono-alkylphenols with different isomeric nonyl-groups. Despite their high persistence and toxicity, exposure to NP induces alterations of the endocrine homeostasis in water organism, bird and mammals. NP can potentially bind to different hormone receptors (e.g. estrogen receptors, progesteron receptors and androgen receptors) and induce or modulate hormone-dependent downstream pathways. The influence regarding the reproductive fitness is much higher in females compared to males.

In the planned study, the follicle fluid will be analyzed in particular for the appearance of NP. Analysis will be done at the Institute of environmental research (Dortmund) in the group of Prof. Spiteller. Basis of this analysis is a chiral gas chromatography - mass spectroscopy that is optimized for the qualitative and quantitative assessment of NP isomers. For further details, see trial design and research setting.

Until now, two preliminary test series were done with at all 34 test persons. Within the first series of measurement, four patients exhibited an increased NP concentration in the follicle fluid (13.7 to 20.9 ng/g compared to 2.1 to 9 ng/g). In the second test series, the NP concentration was less prominent in all analyzed patients (average about 1 ng/ml), but detection of NP was still possible. Thus, NP was detected in all of the analyzed follicle fluid samples. However, the different NP concentration among all tested patients claims certainly the question, whether and how different concentration induce biological effects. The analysis of a large proband cohort regarding the appearance of NP within the follicle fluid facilitates the possibility to estimate a risk appraisal in patients with an unfilled pregnancy. Several parameters will be included for the evaluation: number of MII oocytes, fertilization rate, embryo quality, pregnancy rate, implantation rate and rate of abortions. Despite the duration of infertility and the number of previous IVF cycles will be considered, it is feasible to determine a correlation between the appearance of NP within the follicle fluid and the unfilled desire to have children.