Anti-androgenic compounds in breast milk and cryptorchidism among Norwegian boys in the HUMIS birth cohort

The prevalence of cryptorchidism has increased over the past decades, yet its origins remain poorly understood. Testis descent is dependent on androgens and likely affected by endocrine disrupting compounds (EDCs), targeting the androgen receptor (AR). We investigated the association between anti-androgenic activity, not derived from natural hormones, in maternal breast milk and impaired testis descent among boys. We performed a case-control study based on 199 breast milk samples from 94 mothers of cryptorchid boys and 105 random non-cryptorchid boys participating in the Norwegian HUMIS (Human Milk Study) cohort. For each participant, apolar, and polar fractions were extracted, and combined to reconstitute a mixture. Anti-androgenic activity was measured in all three fractions using the human cell-based in vitro anti-AR CALUX® assay and expressed in μg of flutamide equivalent, a well-known antiandrogen. Results from fraction analyses were compared among boys with cryptorchidism and controls using multiple logistic regression, controlling for appropriate confounders identified using a directed acyclic graph. Children's daily exposure to anti-androgenic EDCs through breastfeeding was estimated to 78 μg flutamide eq./kg of body weigh/day. The activity was higher in the polar fraction (1.48 ± 1.37 μg flutamide eq./g of milk) mainly representing non-persistent chemicals, in contrast to other fractions. However, the activity in the polar extracts was decreased when in mixtures with the apolar fraction, indicating synergistic interactions. No significant difference in the activity was observed according to cryptorchid status for polar, apolar or mixed breast milk fractions. The study showed anti-androgenic activity in nearly all human milk samples, and at levels higher than the advisory threshold. However, no significant association was observed between cryptorchidism and antiandrogenic activity measured in either polar, apolar, or mixture fractions derived from breast milk

Endocrine activities of phthalate alternatives; Assessing the safety profile of furan dicarboxylic acid esters using a panel of human cell based reporter gene assays

FDCA esters are highly relevant biobased alternatives for currently used benzene dicarboxylic acid esters. Despite all the developments on 2,5-FDCA applications, to the best of our knowledge thus far no toxicological data were available for 2,5-FDCA esters. In the present study we aimed to fill this gap, by using an in vitro reporter gene assay approach to compare the activity profile of commonly used phthalates to that of their furan-based counterparts. The assay selection was aimed at the detection of endocrine activity, since several phthalates are heavily scrutinised for their endocrine disrupting properties. However, to avoid missing other relevant toxicological endpoints, several assays able to detect various forms of cellular stress were also included in the panel. The results showed that the (ortho)benzene dicarboxylic acid esters were predominantly active on several of the endocrine assays. In comparison, six of the seven furan dicarboxylic acid based diesters tested here showed no activity in any of the 13 assays used. Only the isobutyl derivative DIBF showed moderate estrogenic activity on one assay, compared to much more pronounced activities on four assays for the ortho-phthalate analogue. Overall, the results presented in this paper are a strong indication that 2,5-FDCA based diesters in general are not only technically viable alternatives to phthalates, but also offer significant toxicological benefits, which supports a non-regrettable substitution

Antagonistic activity towards the androgen receptor independent from natural sex hormones in human milk samples from the Norwegian HUMIS cohort

In this paper, we investigated the possible presence of endocrine disrupting chemicals (EDCs) based on measuring the total estrogenic and androgenic activity in human milk samples. We used specific bioassays for analysis of the endocrine activity of estrogens and estrogen-like EDCs and androgens and androgen-like EDCs and developed a separation method to evaluate the contribution from natural hormones in comparison to that of EDCs to total endocrine activities. We extracted ten random samples originating from the Norwegian HUMIS biobank of human milk and analyzed their agonistic or antagonistic activity using the ERα- and AR CALUX® bioassays. The study showed antagonistic activity towards the androgen receptor in 8 out of 10 of the assessed human milk samples, while 2 out of 10 samples showed agonistic activity for the ERα. Further investigations demonstrated anti-androgenic activity in the polar fraction of 9 out of 10 samples while no apolar extracts scored positive. The culprit chemicals causing the measured antagonistic activity in AR CALUX was investigated through liquid chromatography fractionation coupled to bioanalysis and non-target screening involving UHPLC-Q-TOF-MS/MS, using a pooled polar extract. The analysis revealed that the measured anti-androgenic biological activity could not be explained by the presence of endogenous hormones nor their metabolites. We have demonstrated that human milk of Norwegian mothers contained anti-androgenic activity which is most likely associated with the presence of anthropogenic polar EDCs without direct interferences from natural sex hormones. These findings warrant a larger scale investigation into endocrine biological activity in human milk, as well as exploring the chemical sources of the activity and their potential effects on health of the developing infant

Evaluation of a panel of in vitro methods for assessing thyroid receptor β and transthyretin transporter disrupting activities

We developed a thyroid testing panel to assess endocrine disrupting chemicals (EDCs) capacities to bind either the thyroid receptor β (TRβ) or the thyroid hormones transporter transthyretin (TTR). We first stably transfected a human U2OS cell line with TRβ and a luciferase reporter construct to develop the TRβ CALUX® reporter gene assay to assess chemicals’ potential to interact with TRβ. Secondly, we combined a TTR-binding assay with the TRβ CALUX (TTR-TRβ CALUX) and optimized the system to evaluate the competitive properties of EDCs towards T4 for TTR binding. Both systems were evaluated with a range of known thyroid-disrupting compounds. The agonistic/antagonistic TRβ CALUX successfully predicted 9/9 and 9/12 test compounds, respectively. The TTR-TRβ CALUX predicted 9/9 compounds and demonstrated competitive activities when analyzing waste water samples. We concluded that the proposed test battery is a promising screening method able to efficiently generate data on thyroid hormone interferences by chemicals

Endocrine activities of phthalate alternatives; Assessing the safety profile of furan dicarboxylic acid esters using a panel of human cell based reporter gene assays

FDCA esters are highly relevant biobased alternatives for currently used benzene dicarboxylic acid esters. Despite all the developments on 2,5-FDCA applications, to the best of our knowledge thus far no toxicological data were available for 2,5-FDCA esters. In the present study we aimed to fill this gap, by using an in vitro reporter gene assay approach to compare the activity profile of commonly used phthalates to that of their furan-based counterparts. The assay selection was aimed at the detection of endocrine activity, since several phthalates are heavily scrutinised for their endocrine disrupting properties. However, to avoid missing other relevant toxicological endpoints, several assays able to detect various forms of cellular stress were also included in the panel. The results showed that the (ortho)benzene dicarboxylic acid esters were predominantly active on several of the endocrine assays. In comparison, six of the seven furan dicarboxylic acid based diesters tested here showed no activity in any of the 13 assays used. Only the isobutyl derivative DIBF showed moderate estrogenic activity on one assay, compared to much more pronounced activities on four assays for the ortho-phthalate analogue. Overall, the results presented in this paper are a strong indication that 2,5-FDCA based diesters in general are not only technically viable alternatives to phthalates, but also offer significant toxicological benefits, which supports a non-regrettable substitution.</p