Effects of endocrine disruptors on nuptial pad development

Endocrine-disrupting chemicals (EDCs) are pollutants that interfere with the body's natural hormone system. They can have devastating effects on the development of nuptial pads and the reproductive success of male frogs.

• Inhibited Pad Development: Many EDCs (like certain pesticides, herbicides, and chemicals from plastics like BPA) mimic the female hormone estrogen. When male frogs are exposed to these chemicals, the estrogenic signals can override their natural androgen signals. This results in underdeveloped, small, or completely absent nuptial pads, even during the peak breeding season.
• Feminization and Intersex Conditions: The herbicide atrazine, a common agricultural pollutant, has been shown to induce the production of the enzyme aromatase in male frogs. This causes their natural testosterone to be converted into estrogen, effectively "feminizing" them. This can lead to the development of ovotestis (testes containing eggs) and a complete failure to develop male characteristics like nuptial pads.
• Reduced Mating Success: Without properly formed nuptial pads, male frogs are unable to securely grip females during amplexus. This leads directly to failed fertilization and a severe decline in reproductive rates, which can threaten entire frog populations.