Microplastics (MPs) are plastic particles smaller than 5 mm (especially those within the micrometer range) that are emerging as a significant global environmental pollutant. MPs have been detected in various foods, beverages, and recently in several human biological matrices such as blood, lungs, liver, and feces. Despite MP detection in the human body and the recent reports suggesting their potential to accelerate onset of cancer and cardiovascular diseases, there exists significant knowledge gaps, particularly, the processes of their absorption, distribution, metabolism, and excretion (ADME) within the human body. Pregnancy is a critical period during which MPs may pose significant risks to the developing organism. In vitro studies have shown the uptake and accumulation of nano- and microplastics in the placenta, and MPs have been found in few pregnancy-related human samples like placentas, breast milk, and meconium. However, our knowledge of the fate, effects, and toxicokinetics of MPs in mammalian systems, especially humans, is limited. Therefore, this project aims to investigate whether MP-contaminated food consumption during pregnancy serves as an early exposure route for MPs to reach the fetus. Using animal studies, we will be addressing questions such as "Do MPs cross the placental barrier and reach the fetus? Are the MPs metabolized or excreted from mother's body? Do they accumulate in certain organs or tissues?" This will be achieved by conducting feeding experiments, where pregnant mice will be given MP particles in their diet. Subsequently, the placenta, maternal urine, and fetal organs will be analysed for the presence of MPs, changes in gene expression and histology. The outcomes of this research will help us to identify whether MPs in the fetal environment comes from food and to understand the mechanisms of MP transfer from food within a mammalian system.

1. Handling and Restraint: The mice will be gently restrained for copulatory plug checks, placement into their designated cages, and routine inspection for any signs of injury or distress. 2. Microplastic Feed Administration: Commercially bought Polypropylene [PP] microplastic particles < 20 &#956;m (Nanochemazone, Canada) will be orally administered via diet throughout the gestation period (approximately 18 days), starting from Day 1 of pregnancy until the endpoint. MP particles will be incorporated into standard rodent chow at specified concentrations according to experimental groups (high MP concentration, low MP concentration). The treated feed will be identical to the untreated feed, with the addition of microplastics being the only difference between them. 3. Urine Collection: Urine samples will be collected via catheter insertion on Day 10 of gestation. The animals will be anesthetized using isoflurane during the procedure. Frequency: Single collection 4. Euthanasia: Mice will be humanely euthanized using CO2 followed by cervical dislocation. 5. Sample Collection: Tissues and organs (placenta, liver, kidney, heart, blood, intestine with feces) and pups will be collected post-euthanasia for further analysis and assessment of microplastic effects.

Achieving the aim of investigating microplastic accumulation and toxicity in mammals, particularly during pregnancy, requires animal models like mice due to the complexity of mammalian systems and the need to represent human physiology. Mice are chosen because they share physiological similarities with humans, making them effective models for studying health impacts and toxicology. Alternatives such as cell culture studies and in vitro models were considered but rejected because they cannot replicate the comprehensive interactions and physiological context provided by live animal models like mice. Animal studies are essential for generating empirical data that directly informs potential human health implications associated with microplastic exposure.