17β-estradiol-induced growth-defense tradeoffs in pak choi (Brassica) and implications for intake risk

Estradiol (E2), a natural endocrine disruptor, can be absorbed, accumulated, and metabolized by plants; however, it poses notable risks to the environment and reproductive health of humans and animals. The effects of E2 accumulation in soil used for cultivation remain poorly defined. In this study, we established a soil-based cultivation system to investigate the E2-accumulation dynamics, biochemical responses, and developmental changes in pak choi during its growth cycle. The accumulation of estrogens in roots was always higher than in shoots throughout the cultivation period. Estrone was the predominant accumulation form of the natural estrogens in plant tissues. However, microstructural analyses and antioxidant system indicators revealed irreversible plant damage, leading to compromised harvest quality despite food safety at maturity. Visible morphological traits reflect these differences in quality, enabling consumers to identify risk-free vegetables. Growth and oxidative defense are co-regulated across time and E2 levels, with plants gradually shifting from growth to defense strategies, a previously unrecognized adaptation to estrogen stress. Combining experimental monitoring with modeling, we quantified the E2-associated risks and assessed the risk quotient of total natural estrogens after E2 transformation. The intake risks of pak choi initially increased and subsequently declined, with the edible portion at harvest being risk-free (hazard quotient <1). This study provides the first evidence of the long-term effects of E2 on pak choi under natural soil conditions, offers key insights into the link between plant physiology and dietary risk, and supports the establishment of science-based thresholds for natural estrogens in crop production systems.