Our Stolen Futurea book by Theo Colborn, Dianne Dumanoski, and John Peterson Myers
 
 

 

 

Emerging science on the impacts of
endocrine disruption on reproduction and fertility

2007: Testosterone declining in Massachusetts men
for a 2001 review of endocrine disruption and testicular development

 
 

Given the central role that hormones play in guiding the development of the reproductive system and then in controlling its activities once developed, it is not surprising that a major focus of endocrine disruption research has been on reproductive health. Our Stolen Future reviews many studies, especially experimental work with laboratory animals, that document endocrine disruption of the reproductive system. These include reductions in fertility, alterations in sexual behavior, deformations of the reproductive tract and reproductive diseases.

Research reported since the publication of Our Stolen Future has continued to explore these themes. The animal literature has emphasized mechanistic understanding of how endocrine disruptors work, with new revelations on the exquisite sensitivity of the developing fetus to chemical hijacking. Research on mixtures showing fetal loss in mice even to very low levels of herbicides suggests that current regulatory toxicology is probably failing to protect public health.

The research on people has attempted to resolve several controversies (for example, whether sperm count is declining, and if so, why?), to determine whether several reproductive system cancers (especially breast cancer) are linked to organochlorine contaminants, and to establish trends in reproductive tract disorders in men and women, for example, hypospadias and endometriosis. Analysis suggests that sperm declines, hypospadias, cryptorchidism and testicular cancer are different manifestations of the same syndrome, testicular dysgenesis syndrome.

Now some scientists have even begun to question whether the "demographic transition" ... the decline in birth rates associated with improving economic conditions... may have an involuntary component linked to contamination-impaired reproduction. The traditional explanation is that as economies improve and childhood survival increases, women make voluntary choices to have smaller family sizes. More...

Concerns have also been raised about links between cryptorchidism in people (affecting about 3% of newborn males) and in utero exposure to organochlorines. Research is firming up those links and also revealing their molecular basis. More...

New issues have arisen, also, which based on animal studies may involve endocrine disruption, including reductions in the age of puberty and changes in the human sex ratio. A recent study even suggests eating contaminated fish may impair a woman's ability to conceive children.

Another new study shows that women within a few miles of where pesticides are used on agricultural fields have an increased risk of having their fetus dying during pregnancy.

Experimental studies in the laboratory have proven crucial to revealing important impacts, identifying human health endpoints that should be examined, clarifying mechanisms, and exploring questions about sensitivity to low doses and to mixtures. They have also been essential to documenting different types of endocrine disruption and to establishing which compounds have hormonal effects.

Some points of entry:

 
 

 

Recent relevant results:

September 2002. Research conducted at the University of Wisconsin reveals that a commercial mixture of herbicides including 2,4-D causes fetal loss in mice. Adverse effects were caused even at the lowest dose tested, one which current EPA standards regard as safe. These results indicate that mixtures must become a focus of regulatory testing for toxicology, and that current standards are not adequate. More...


June 2001: Skakkebæk et al. summarize emerging evidence that a collection of adverse conditions in male reproductive health have their basis in a common origin, specific errors during the development of fetal testes. They propose that this collection of disorders should be recognized as a syndrome, testicular dysgenesis syndrome (TDS), and that it is likely to be caused by environmental factors in many cases. More...


March 2001: In a cautious and substantial scientific review of, Richard Sharpe concludes that until the appropriate live animal and human studies completed, "the safety of hormonally active environmental chemicals, especially in mixtures, will continue to give cause for concern as far as testicular development is concerned. More...


May 2000: Scientists report remarkably low sperm counts from young men in Denmark. More than 40% had counts below 40 million per ml, a level at which reproductive impairment begins to be detectable. More...


May 2000: Independent research confirms the validity of low dose impacts of bisphenol A. Industry spokespeople had mounted an aggressive campaign to paint research by Dr. Fred vom Saal (Univ. Missouri, Columbia) as impossible to replicate and therefore invalid. A new publication by Dr. Chhanda Gupta (School of Medicine, University of Pittsburgh), refutes that claim. More...

May 2000. Italian researchers report that fathers exposed to dioxin by an industrial accident in Seveso, Italy, are less likely to sire male offspring as a result of dioxin exposure. More...

May 2000: A flawed study is cited inappropriately by the press as showing that US sperm counts are holding steady. More...

 
March 2000: DDT can cause permanent and functional sex reversal in fish, such that chromosomal males bear fertile young. More...

 

 

 

 

 

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