Integrating physiologically based toxicokinetic and fugacity formalisms to quantify the transfer of polychlorinated dioxins and furans (PCDD/Fs) from soil to beef meat.
Integrating physiologically based toxicokinetic and fugacity formalisms to quantify the transfer of polychlorinated dioxins and furans (PCDD/Fs) from soil to beef meat.
Dans: 11th Workshop on Modeling Nutrient Digestion and Utilization in Farm Animals (MODNUT). 9 September, Ed. Agroscope, Engelberg (CH). 2025.
Introduction: Ruminants may be exposed to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) through soil uptake (a PCDD/F sink), threatening milk and meat safety (Vernez et al., 2023). This study aims to quantify PCDD/F transfer from soil to beef and veal meats, using two dynamic models describing absorption, distribution, metabolism and excretion (ADME) of lipophilic contaminants in suckler cows and growing cattle. Material and methods: Two physiologically based toxicokinetic (PBTK) models, RuMoPOP for lactating cows (Lerch et al., 2025) and BeefPOP for growing cattle (Lerch et al., 2022), were used to simulate the PCDD/F transgenerational fate in suckler cow over 3 gestation-lactation cycles (1965 kg milk over 300 d), slaughtered after 65 d dry-off, and offspring calf (mean animal types Angus × Hereford steer and Montbéliard bull, from 3rd calving), slaughtered at 150 d for veal meat, or 365 d for beef meat (weaning at 300 d). A PCDD/F constant exposure through diet [up to 1.0 ng toxic-equivalent (TEQ)/kg dry matter (DM)] until slaughter, or followed by a depuration phase from 181 d before slaughter (diet at 0.1 ng TEQ/kg DM, after constant exposure), were considered. PCDD/F levels in soils, feeds, and calf adipose tissues from a suckler beef farm in the Lausanne area (Switzerland, Vernez et al., 2023) were compared with simulations, to evaluate model performance. Results and discussion: For a constant PCDD/F exposure (Fig. 1A) with 1 % soil in DM intake, the maximum soil concentrations ensuring compliant meat [maximum level (ML) of 2.5 pg TEQ/g lipids, EU No 1067/2013] were 9.8, 14.9, and 22.4 ng TEQ/kg DM for veal, young beef, and culled cow, respectively. This suggests that a feed ML of 0.85 ng TEQ/kg DM (EU No 277/2012) may not ensure compliant meats. A depuration phase allowed exposure soil concentrations to be 3- and 1.6-fold higher for young cattle and culled cows, respectively (Fig. 1B). On-farm measurements (1.2 % soil at 7.2 ng TEQ/kg DM prior depuration) aligned well with model simulations for adipose tissue from young cattle (365 d), confirming the models’ predictive capabilities. Conclusion: The presented models combining the fine descriptions of ADME and cattle physiology effectively predict PCDD/F toxicokinetics under various scenarios. They provide valuable insights into contamination risks, emphasizing the need for management strategies depending on soil PCDD/F levels and farming system.
