How do electrostatic fields from polyester disrupt sperm production?

Polyester fabric generates electrostatic fields when it rubs against the skin, and research has shown these fields can significantly disrupt spermatogenesis, the process by which sperm cells are produced in the testes. Dr. Ahmed Shafik's studies demonstrated that the electrostatic potential difference created between polyester fabric and scrotal skin interferes with the bioelectrical environment that Sertoli and Leydig cells need to function. These cells are responsible for supporting sperm development and producing testosterone, respectively.

The electrostatic effect is distinct from the chemical concerns associated with polyester. Even a perfectly inert polyester fabric would still generate friction-based static charges against the skin. This makes it a physical property of the material that cannot be engineered away through cleaner manufacturing. The electrical disruption appears to suppress the hormonal signaling within the testes that triggers germ cell maturation, effectively shutting down sperm production over time with continuous exposure.

Natural fibers do not generate the same electrostatic profiles. Cotton, wool, hemp, and linen have different triboelectric properties that produce little to no disruptive charge when in contact with skin. This is one reason why the Shafik study found that men who switched from polyester to cotton underwear experienced full recovery of sperm counts. For men concerned about fertility, the fabric of their underwear is not a trivial choice.