Abstract: ObjectiveTo study the thyroid toxicity in male rats exposed to di-2-ethylhexyl phthalate (DEHP) and the recovery effect after removing exposure factors.MethodsSprague Dawley male rats were randomly divided into DEHP-exposed group and DEHP-exposed recovery group, both of which were re-divided into subgroups of negative control, low-dose, middle-dose, and high-dose, separately exposed to 0.0, 50.0, 158.2, and 500.0 mg/kg BW DEHP by gavage. The DEHP-exposed group was exposed to DEHP for 13 weeks; the DEHP-exposed recovery group was recovered for 6 weeks after the exposure. At the end of the exposure, pathological changes of the thyroid tissue and levels of serum triiodothyronine three (T3), thyroxine (T4), and thyroid stimulating hormone (TSH) were examined and contents of Glutathione Peroxidase (GSH-Px) and Malondialchehyche (MDA) in thyroid tissue were measured. ResultsAfter 13 weeks of DEHP exposure, the rats were in good general condition and had no significant changes in body weight. Levels of T4 in middle-dose subgroup and of T3 and T4 in high-dose subgroup were lower than those in the negative control subgroup (P<0.05). In the high-dose group, the size of thyroid follicles and colloid density decreased, and the edema of follicular epithelial cells was observed. Compared with the negative control subgroup, the GSH-Px activity of the thyroid tissues was decreased and the content of MDA was increased in the high-dose subgroup (bothP<0.05). After 6 weeks recovery, thyroid hormone levels and thyroid pathological changes had no significant difference between the DEHP-exposed recovery group and DEHP-exposed group (bothP>0.05). GSH-Px activity of the thyroid tissue was lower and the MDA level was higher in the DEHP-exposed recovery group compared with those in the DEHP-exposed group (bothP<0.05). ConclusionDEHP has toxicant effects on thyroid in rats and the oxidative stress injuries might be one of the possible mechanisms. After 6 weeks of recovery, the thyroid function was not significantly restored, and the oxidative damage by DEHP on thyroid was further aggravated. Therefore, the damage of DEHP on thyroid tissue was irreversible.