10th German Pharm-Tox Summit / 91. Jahrestagung der Deutschen Gesellschaft für Experimentelle und Klinische Pharmakologie und Toxikologie (DGPT)

Chair

Prioritisation of potential toxic co-formulants for pesticide risk assessment using NAMs

Mixture Toxicology

TOX03

Plant protection products (PPPs) include active substances (AS) and various co-formulants. AS are primarily responsible for the effectiveness of PPPs, while co-formulants enhance AS efficacy. However, the contribution and interaction of co-formulants with each other or with AS are not systematically assessed. To address this issue, we propose an approach to identify potentially toxic co-formulants and prioritise PPPs for further testing using New Approach Methodologies (NAMs). For this purpose, we prioritised co-formulants for further in vitro testing using in silico tools as well as PPP sales data. In silico specific target organ predictions were filtered by a scoring system combining multiple independent models as well as criteria for co-formulant concentration in the PPP. Regarding hepatotoxicity, 36 co-formulants were flagged in 161 PPPs whilst 31 co-formulants were flagged in 235 PPPs with respect to nephrotoxicity. In addition, an in silico ADME tool was employed in this prioritisation scheme, identifying 56 co-formulants as potential inhibitors of P-gp active transporter or CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 in 215 PPPs. For the same targets, 65 hepatotoxic AS were flagged as potential substrates. As a next step, comparative cytotoxicity was conducted in six prioritised PPPs along with their respective AS in HepaRG cells. Priority was given to three PPPs which dominated AS cytotoxicity and for which dose-addition modelling was conducted. Product 5 elicited additive effects but yet the one co-formulant (i.e. Solvent naphtha) prioritised based on PPP sales data did not show any inhibitory effect on CYP1A2. In contrast, Product 6 displayed more than additive effects and was thus investigated for kinetic interactions taking into account the in silico ADME predictions. Regarding P-gp interactions, prothioconazole was not a substrate for the P-gp transporter, nor did the prioritised co-formulant (N,N-dimethyldecanamide) inhibit this active transporter in vitro, contrary to ADME predictions. However, N,N-dimethyldecanamide was an inhibitor of CYP2C19 in vitro with an IC50 value of 4.05 μM confirming the in silico predictions but tebuconazole flagged as a potential CYP2C19 substrate was not confirmed in vitro. In summary, the inclusion of potential toxicokinetic mixture effects between co-formulants and AS increased the number of prioritised PPPs minimising the chances of overlooking such interactions contributing to the overall toxicity of PPPs.

Toxicology

Short talk

Prof

The ring trial MATCHING shows high inter-study reproducibility of plasma metabolomics data after 28-day treatment in rats

Regulatory Toxicology

TOX06

Metabolomics has proven its value for in vivo rat studies and numerous ongoing activities are developing guidance on the conduct and reporting of metabolomics data for regulatory application.The Cefic-funded MATCHING study was conducted to determine the reproducibility/ reliability of metabolomics data for the grouping of chemicals through a fully blinded ring trial. For this purpose, 8 compounds (cpds) with 3 different MoAs (endocrine activity (ED), peroxisome proliferation, anaemia) were selected based on metabolome data available in the BASF metabolomics database MetaMapTox (MMTox) from earlier rat studies. Plasma samples for the ring-trial were derived from a newly conducted 28-day rat toxicity study (animal welfare appr.no. 23 177-07/G 18-3-098), aliquoted, and distributed to the partners. The animals were treated with similar doses as in the earlier studies. Each metabolomics laboratory applied their LC-MS metabolomics workflows to acquire, process and statistically analyse the plasma samples. This included grouping the cpds based on their metabolomics signatures. As reported earlier, 5 ring-trial partners generated high-quality metabolome data and discovered the identical grouping of the 8 cpds into 3 categories (Viant et al., 2024).At BASF, as quality control for the ring trial samples, the metabolome data was additionally evaluated against MMTox in a fully blinded manner. This evaluation showed that using an unbiased statistical correlation approach, the plasma metabolome of the blinded cpds was highly similar to those from the corresponding treatments in MMTox. The similarity was highest for peroxisome proliferators in both sexes - e.g., the blinded cpd TS 9 (Fenofibrate) matched best with the Fenofibrate treatment already available in MMTox. The ED cpds were synthetic androgens, which showed high metabolomic similarity in males. In females, they showed similarity with several ED cpds, but not exclusively androgens. The metabolomic similarity was lower for anaemia cpds, likely due to the lower overall impact on the metabolome. When evaluating the cpds against pre-defined patterns for toxicity (consisting of metabolites commonly changed for specific toxicological modes of action) available in MMTox, the MoAs of all 3 groups were confirmed in both sexes.The data from the blinded MATCHING ring-trial show high inter-study reproducibility not only of the metabolome data derived from rat plasma, but also the underlying 28-day in vivo study in rats.

Prof.

Detection of the Restricted Phthalate Mono-n-hexyl phthalate (MnHexP) in the Urine of Young Children: Human-Biomonitoring Data from the KiSA-Study NRW Germany

Phthalates are a large group of chemicals mainly used as plasticizers. Some phthalates are classified as toxic to reproduction and these phthalates are subject to extensive restrictions and bans in the EU. Despite regulatory measures, children continue to be exposed to phthalates known to be toxic to reproduction. In autumn 2023, mono-n-hexyl-phathalate (MnHexP) was found in urine samples from children (KiSA Study NRW) and adults (GerES VI) in Germany. These findings are surprising, as MnHexP is a primary metabolite of di-n-hexyl-phthalate (DnHexP), a substance with no active registration as substance in use in the EU.The results shown here are part of the HBM survey of the state of North Rhine-Westphalia, Germany (KiSA-Study NRW) which investigates the exposure of children to pollutants at regular intervals of 3 years in order to identify exposure trends. The aim of this study was to estimate the exposure of young children in NRW to DnHexP. MnHexP was measured in 503 spot urine specimens obtained from preschool children aged 2-6 years collected between October 2017 - Mai 2018 (Cycle 3) and July 2020 – July 2021 (Cycle 4). Quantification was done by isotope-dilution mass-spectrometry coupled to high performance liquid chromatography (HPLC-MS/MS).MnHexP was found in concentrations above the limit of quantification (LoQ; 0.2 µg/L) in 26 % in cycle 3 and increased to 61 % in cylcle 4. Median MnHexP concentration was < 0.2 μg/L in cycle 3 and increased to 0.56 μg/L in cycle 4. The 95th percentile was 0.81 μg/L and 8.73 μg/L, respectively. This corresponds to a significant increase in exposure by a factor of 10 within three years. All exposures were below the health-based guidance value for MnHexP of 60 µg/l (HBM-I-value). No significant differences were found between sexes or the degree of urbanization. However, there appears to be a significant association between the use of sunscreen shortly before sampling and urinary MnHexP excretion. The median MnHexP concentration of children who used sunscreen shortly before sampling was 4.7 times higher compared to children without apparent use of sunscreen.

Plenarsaal HS A

Kurzvorträge Toxikologie

Short talk 10

Short talks

Short talk 10
Regulatory Toxicology

Appointment

Chair

Programme

Short talk 10Regulatory Toxicology

Appointment

Chair

Programme

Short talk 10
Regulatory Toxicology