The studies are done on rats ingesting high doses of Boric Acid, every day for weeks. The Wikipedia page also mentions testicular atrophy was noticed in dogs af

The studies are done on rats ingesting high doses of Boric Acid, every day for weeks. The Wikipedia page also mentions testicular atrophy was noticed in dogs after ingesting 32mg/kg body weight for 90 days. That's like a human eating about 2g of the stuff every day, on par with your needed daily intake of salt. That would be a lot of boric acid... In our case were only concerned with external application and there doesn't seem to be any noted effect there.