Toxicological Impacts of Certain Herbicides on Reproductive System and Thyroid Gland in Male Rats

This study examined the effects of four commonly used herbicides (Glyphosate, Dicamba, S-metolachlor, and Cyhalofop-butyl) on male rats. Animals were orally administered 1/10 LD₅₀ of the tested herbicides for four weeks /three times a week, at the end of the experiment, biochemical, hormonal, sperm, and thyroid parameters were investigated. The results indicated that exposure to tested herbicides increased malondialdehyde (MDA) levels. cyhalofop-butyl showed the highest value (12.64 nmol/mL) compared to the control given oil only (4.12 nmol/mL). Antioxidant enzymes such as catalase and superoxide dismutase (SOD) were significantly reduced in all treated groups, especially in the cyhalofop-butyl group (8.76 ng/mL and 7.86 U/mL, respectively). Reproductive hormones were also markedly decreased. The cyhalofop-butyl group had the lowest testosterone (2.44 ng/mL), luteinizing hormone (1.76 mIU/mL), and follicle-stimulating hormone (1.44 mIU/mL) compared to untreated group (testosterone: 4.5 ng/mL in oil; LH: 3.04 mIU/mL; FSH: 2.44 mIU/mL). Sperm quality was dramatically affected, with significant decreases in progressive motility, increased deadand abnormal sperm, and lower the total number of sperms, particularly in dicamba and cyhalofop-butyl treated rats. Additionally, thyroid hormone profiles were disrupted, where glyphosate and Dicamba increased T3 and T4 levels (T3: 2.18 - 4.02 T4: 14.2–17.34 ng/mL respectively), reducing TSH (0.31and 0.33 mIU/mL respectively), suggesting possible hyperthyroid-like effects. The most important findings demonstrated that the tested herbicides, especially cyhalofop-butyl and dicamba, can cause serious oxidative, hormonal, and reproductive damage in male rats. These findings raise concerns about the endocrine-disrupting potential of these herbicides and the need for more regulatory evaluation and safer alternatives.