Chemicals linked to declining sperm counts

Posted by egable on February 5th, 2008 filed in Health

Common household chemicals and widespread pollutants have lead to a 1.15 percent per year decline in male sperm counts globally from 1940 to the 1990s, according to a Colorado State University researcher.

Rao Veeramachaneni, a biomedical sciences professor at CSU, has found that chemicals including insecticides, pesticides, common pollutants in ground water, and chemicals in plastics, make-up and nail polish are among a growing list of culprits causing developmental abnormalities such as hypospadias and cryptorchidism, impaired sperm quality and impotence. Reproductive health can be compromised if males are exposed at various times in life, spanning from in utero up to adulthood.

Veeramachaneni has found effects worldwide and in species from humans to horses and frogs. His research, coupled with the collective findings of other experts in the field, indicates a strong link related to pollutants, and incidence of such impacts continues to increase from year to year as chemicals infiltrate the modern world.

Some of these chemicals can survive in the environment for 30 to 40 years, and the chances for exposure are high because the chemicals have permeated our world. For example, the EPA says that about one-third of the nation’s lakes and one-quarter of its rivers are polluted. There is also evidence that exposure today to some of these chemicals can affect the reproductive health of this generation as well as the future health of offspring of those exposed. The incidence of testicular cancer in young men 15 to 35 years old has increased three- to four-fold over the past 50 years, particularly in the Western world.

These chemicals affect the body through several channels. They attach to receptors in the body that help hormones carry out their functions and either block actual hormones from attaching or mimic the expression of the real hormones, causing confusion in the male body. In addition, some interfere with the body’s natural production of hormones.

A pattern emerges when comparing the explosion of the world’s use of chemicals, including pesticides and herbicides, and the steadily increasing incidence of testicular cancer, reproductive system abnormalities and impotence.

In a series of studies funded by the Environmental Protection Agency, Veeramachaneni’s laboratory found that exposing tadpoles to dibutyl phthalate, one form of phthalate, drastically slows their growth and reproductive development. At varying doses, tadpoles lagged weeks behind non-exposed frogs in developing legs and entering adulthood. More significant, however, was the impact on their ability to reproduce; one effect of the chemicals is particularly notable on their mating calls. Those exposed to chemicals had calls that were weaker and shorter. Images of the larynx, the voice box, showed that it was significantly underdeveloped. Without a competitive mating call, the frogs will not be able to reproduce successfully.

Phthalates, which are used in a variety of products including cosmetics, upholstery, pharmaceuticals and medical tubing, and also are found in drinking water and air. The chemicals can be found in body fluids of people who have been exposed, including in urine, blood and breast milk. Presence in breast milk can pass exposure on to an infant.

DDT and other pesticides and herbicides have also been linked to testicular cancer in humans and animals. In collaboration with medical scientists at University of Pretoria in South Africa, Veeramachaneni has found instances of testicular cancer in wildlife in Africa, potentially tied to the increasing renewed use of DDT to fight malaria-carrying mosquitoes. His research showed that DDT causes precancerous lesions in the testes. Veeramachaneni also documented cancerous lesions in the testes of infertile domestic horses and wild deer, and is working on a possible connection to ubiquitous pollutants.

The incidences of hypospadias and cryptorchidism are increasing. While figures indicating the increase vary by population, the Centers for Disease Control and Prevention cites a marked two-fold increase in the last 25 to 30 years, now impacting almost one per 100 males born. Hypospadias, a birth defect of the urethra, can affect urination and sexual function. Cryptorchidism is the absence of the scrotum from one or both testes .Veeramachaneni’s laboratory has found that exposure to some chemicals such as phthalates causes hypospadias and cryptorchidism.

Historical studies show that the quality of sperm in humans has decreased rapidly in the last 50 years. With the assistance of research associate Carol Moeller, Veeramachaneni’s electron microscopic studies show that sperm quality is affected by malformations of structures that are needed for fertilization of the egg or two or more sperm attached to each other following exposure to a variety of so-called innocuous chemicals.

Erectile dysfunction, which is reported in one-third of the U.S. male population, also is being linked to chemicals in the environment. Vinclozolin, a fungicide commonly used in agriculture, can contaminate food and water supplies. In laboratory tests, Veeramachaneni and his research associate, Jennifer Palmer, found that some male offspring of animals exposed to vinclozolin during pregnancy displayed a complete lack of interest in females.