Research progress on the interference effects of plasticizers on maternal behavior and its potential mechanisms.

Environmental endocrine disrupting chemicals (EDCs), known as environmental hormones, are exogenous chemicals that can disrupt hormone levels and cause dysfunction of the secretory system in humans and animals. Plasticizers, which are widely used EDCs, are commonly used to enhance the flexibility of plastic products. As plastics age and wear, however, they can leach into the environment and enter the bodies of animals through various pathways such as the digestive tract and skin. They can lead to estrogen-like effects and have substantial reproductive toxicity. Residual plasticizer concentrations in the environment are typically low. Unlike high doses that induce acute damage to the reproductive system, low doses of plasticizers do not cause macroscopic harm and thus its reproductive toxicity is often overlooked for extended periods. An increasing number of studies conducted on humans and mice in recent years have demonstrated that low doses of plasticizers can induce reproductive toxicity by interfering with maternal behavior. Prenatal exposure to plasticizers can result in abnormal postnatal maternal behavior. Female offspring also exhibit significantly low maternal care, lactation, and other behaviors in adulthood, which may persist for multiple generations, significantly disrupting the animal breeding process and impacting the health and well-being of newborn pups. The underlying mechanisms have not been systematically summarized. The risk of continuous exposure to low-dose plasticizers in humans and animals has increased due to the extensive utilization of plastic and rubber products in modern production and lifestyle patterns. It is thus crucial to conduct a systematic review on the effects of low-dose plasticizers on maternal behavior. We reviewed the research progress on the disruptive effects of plasticizers on animals' maternal behavior and concluded that these effects are primarily caused by inducing oxidative stress damage and DNA methylation reprogramming in the hypothalamic-pituitary-ovarian axis, as well as disrupting the balance of the thyroid system and causing intestinal microbial disorders. It would offer a novel perspective for future studies about the influence of plasticizers and other environmental hormones on maternal behavior in domesticated animals.