Endocrine Disruptors and the Transgendered

It's a fact that harmful chemicals like DDT are responsible for certain intersex conditions, but have the increased presence of human-made chemicals in the environment created a rise in the transgender population? For an environmental perspective on the incidence of transsexuality and intersexuality, read Christine Johnson's Endocrine Disruptors and the Transgendered. Johnson is a co-founder of TransAdvocate, an educational and advocatory site about endocrine disruptors and trans civil rights.

By Christine Johnson

Despite popular opinion and negative media portrayals which disparage transgendered people as being "mentally ill" or making "lifestyle choices," an increasing amount of evidence is surfacing which is linking the proliferation of endocrine disrupting chemicals (EDCs) to variations in gender identity and sexual orientation. In an invited paper published in the December 2001 issue of Neuroendocrinology Letters, Dr. Günter Dörner outlines the various purported causes of transsexualism, which fall into two general classes: 1) genetic enzyme mutations and 2) so-called epigenetic effects which include stressful prenatal/postnatal situations and fetal exposure to endocrine disruptors such as the pesticide DDT and its breakdown products.

The authors studied the prevalence of polycystic ovaries (PCO), idiopathic oligospermia [low sperm count with no identified cause] (IO), and transsexualism (TS) in East and West Germany over the last 50 years, and correlated increases in these conditions with the use of DDT in the two countries. They found that after 1960, (when DDT usage was high) "clearly increased dehydroepiandrosterone sulfate [DHEA-s] levels and ratios to cortisol were found, suggesting again the possible co-responsibility of DDT and its metabolites for the development of transsexualism." They also found that PCO commonly occurred in combination with female-to-male transsexualism, and IO typically occurred in combination with male-to-female transsexualism, suggesting multiple effects from endocrine disruption.

As for the effect of these chemicals on the brain during development, several studies have been performed which examined various areas of the hypothalamus— a section of the brain involved in gender and sex— to see if any sex differences were present. In a 1995 article published in Nature entitled "A Sex Difference in the Human Brain and its Relation to Transsexuality," the authors showed that male-to-female transsexuals have female numbers of neurons in a region of the hypothalamus known as the bed nucleus of the stria terminalis (BSTc). [Reprinted in the International Journal of Transgenderism, and available online at http://www.symposion.com/ijt/ijtc0106.htm.] A later study found that a female-to-male transsexual had male numbers of neurons in this region, supporting the idea that this brain region is responsible for gender identity in humans. Similar structures have been identified in animals which corroborate these findings.

Over the last decade, a significant amount of research has been performed showing that EDCs are having a major impact on sexuality and reproduction in wildlife. In the UK, alkylphenols and phthalates have been identified as the prime suspects for feminized fish in some areas. These chemicals are persistent breakdown products of alkylphenol ethoxylates, chemicals used in industrial detergents and as inert ingredients in pesticides. In Florida, an extensive spill of DDT and dicofol in Lake Apopka resulted in male alligators with abnormally small penises, abnormalities of the testes, and altered levels of sex hormones. Male gulls in the Great Lakes region of the US have been found to have "female (ovarian) type structures," due to high levels of DDT and DDE in the eggs. Male Florida Panthers have been found to have undescended testicles and a number of reproductive problems, and both males and females are found to contain high levels of several endocrine disrupting chemicals. For a more comprehensive review, see Poisoning the Future: Impacts of Endocrine Disrupting Chemicals on Wildlife and Human Health.

Regarding the situation in the Northwest, a study was published in Environmental Health Perspectives which showed that 84% of genetically male Chinook salmon appeared to be female in the Columbia river. Regarding the cause, lead author James J. Nagler of the University of Idaho reports that pesticides and other chemicals that are estrogenic have been detected in the river and may play a role in this observed sex-reversal. [Source: "Sex Changed Salmon," in Scientific American online.]

In the laboratory, similar results are found when animals are exposed to hormone disrupting chemicals. In her book Our Stolen Future, author Theo Colborn relates the story of two Syracuse University researchers, who in 1950 injected roosters with DDT for two to three months. They found that the roosters’ testicles only reached 18% of the size of the controls, and the typical male secondary sex characteristics were significantly suppressed. It is interesting to note that Harry Benjamin, a New York endocrinologist and sexologist who wrote the first modern work on transsexualism, The Transsexual Phenomenon in 1966, found that 40% of his male-to-female and 45% of his female-to-male patients had some degree of hypogonadism (reduced size of testicles/ovaries).

But despite the 1972 ban on DDT in the US, the chemical and its metabolites keep showing up in pregnant women. A 2000 study published in The Journal of Clinical Endocrinology and Metabolism measured the levels of several pesticides in amniotic fluid during the second trimester. The authors found that "…approximately one out of three human fetuses in Los Angeles is exposed to p,p’-DDE [a DDT breakdown product] at physiologically relevant levels." They also added "Although we did not test for adverse health effects in this phase of the study, the concentrations of contaminants measured are sufficient to be cause for alarm." [Source Abstract]

However, DDT is hardly the only endocrine disruptor in existence. Our Stolen Future’s website lists 85 chemicals which are known to be endocrine disruptors or classes of chemicals such as PCBs and dioxins, which have many variants. Phthalates are often used in plastic food packaging as a softener, and Bisphenol-A is used to line metal cans to eliminate the metallic taste and is commonly found in resins, plastics and dental sealants. Mercury is one of the most widespread EDCs, being present in dental amalgam and childhood vaccines, and lead is commonly found in Seattle water, reportedly due to the corrosion of lead in home plumbing because corrosive chemicals are used for disinfecting the water. [Source] Mercury is a special case, in that it is the only known endocrine disruptor which is deliberately implanted in the body. (dental amalgam contains 50% mercury) The pesticides, of which there are many, are intentionally released into the environment, often in homes and schools. Additionally, the vast majority of chemicals currently in production have never been tested for endocrine disruption effects.

So is it a coincidence that since the introduction of the chlorinated pesticides around 1935-1940 that the rate of transsexualism has been climbing steadily? The first generation born after the introduction of pesticides was also the first generation to have significant numbers of transsexuals. The condition is virtually absent from the US historical record prior to 1952, when Christine Jorgensen made headlines. Every generation since has had higher and higher rates. Clearly researchers knew that sexual developmental changes were observed with DDT in animals as early as 1950, yet this information was ignored, deliberately or not. Fifty years later, large numbers and quantities of EDCs are being distributed around the globe without adequate consideration of the consequences.

This line of inquiry which is examining the relationship between EDCs and transsexualism has an obvious relationship to the civil rights and social perceptions of transsexuals. It will likely lead toward restoration of full civil rights as the law catches up with emerging science, and should also increase understanding among the general public as more evidence is uncovered and as doctors improve their understanding of the specific biochemical changes and structural effects that are associated with exposure to EDCs during development. For more information on this topic, visit http://www.antijen.org/transadvocate— a transgender advocacy group co-founded by myself and Angela Kimble— with the mission of educating the transgendered community and the general public about the relationship between endocrine disruptors and gender variance, and to advocate on behalf of the transgendered community for full civil rights.