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Public Radio's Environmental News Magazine (follow us on Google News)

Hormone Disruptors Linked to Genital Changes and Sexual Preference

Air Date: Week of
Tyrone Hayes' at work in his lab in Berkeley (Photo: Ashley Ahearn)

Scientists continue to sound the alarm about some common chemicals, including the herbicide atrazine, and link them to changes in reproductive health and development. Endocrine disrupting chemicals have been found to feminize male frogs and increase the incidence of homosexual behavior among those amphibians. Ashley Ahearn reports on how these substances may be affecting human development and behavior.


CURWOOD: Well, the impacts of endocrine disruptors on sexuality and reproduction is a subject we’ve covered widely here at Living on Earth. A while back producer Ashley Ahearn reported how potentially disruptive contact with these hormone mimicking chemicals can be. Dr. Tyrone Hayes of UC Berkeley was investigating the effects of the endocrine disrupting pesticide Atrazine, which seems to affect the development of male frogs, causing them to become feminized, and to engage in homosexual behavior. Pediatric endocrinologist Stanley Rosenthal of UC San Francisco believes some of these same effects may be showing up in humans. Here’s part of Ashley’s report.

¬AHEARN: So, what about us? Could endocrine disruptors be having feminizing effects in humans? No one knows for sure, but some believe that rising rates of one birth defect could be an indicator.


AHEARN: Dr. Laurence Baskin is a pediatric urologist with the University of California, San Francisco but he practices here at the Oakland Children’s Hospital part of the time.

Today he’s performing back-to-back surgeries - and a very specific type of surgery. Baskin specializes in correcting hypospadias – the second most common birth defect in the country behind heart disease.

BASKIN: About one in 125 to one in 250 newborn males has an abnormality in their genitalia that could be described as hypospadias – and what I mean by that is penile curvature, abnormal urethra and an abnormal foreskin and putting that together that’s what hypospadias is defined as.

AHEARN: More babies are born with hypospadias than Down’s syndrome or cleft palate, and some research suggests that rates of hypospadias have increased in the past few decades. Baskin and others in his field suspect environmental exposures may contribute to hypospadias.

All fetuses are programmed to develop ovaries unless they’re told otherwise by certain hormones like testosterone and androgen.

Endocrine disrupting chemicals, like atrazine for example, could gum up the receptors for those hormonal messengers that tell a fetus to develop into a baby boy– or as Baskin explains – prevent the fetus from fully masculinizing.

BASKIN: The penis wouldn’t develop. It would be arrested meaning that your urethral opening would be lower down in the penile shaft, the penis normally as it develops is curved and it straightens out so in Hypospadias it wouldn’t have straightened out and the foreskin would only have formed on the top of the penis, wouldn’t have come down to the bottom because that lock or that hormone receptor would be blocked or disrupted by the environmental toxin.

AHEARN: Ok, so if Tyrone Hayes is finding feminizing effects in frogs who are exposed to Atrazine – one of these environmental toxins that Baskin is talking about – are there some parallels to be drawn in human beings? Baskin pauses for just a split second before responding.

BASKIN: Humans clearly are not frogs, but the theory is correct. And in this case we would agree with Dr. Hayes that an environmental disruptor, something in the environment, chemical toxin or medication could certainly be a risk factor for Hypospadias.

AHEARN: Baskin says the majority of hypospadias can be fixed with a relatively quick surgery that can make life a lot easier for the child later on.

BASKIN: I think growing up as a teenager and not having normal genitalia would be tough enough, even if you have normal genitalia, for regular emotional and sexual development so that’s really the major reason to fix it, so kids can be normal.


AHEARN: But “normal” is a loaded term for some. Dr. Tiger Howard Devore is a sex therapist and clinical psychologist in New York City.

DEVORE: Isn’t it great that some doctor can tell you what’s normal? I love that.

AHEARN: For Devore, this is a personal story.

DEVORE: One of my earliest memories is of being in a hospital and dealing with some physician taking bandages off of my genitals and watching my parents respond in obvious fear about whatever it was that this guy was doing. I was probably maybe three. But I had my first surgery when I was three months old and I had at least one surgery every year after that until I was at least 12.

AHEARN: Devore was born with severe hypospadias. All told, he’s had 20 operations on his penis.
It wasn’t until college that Devore came to terms with his condition and decided to devote himself to helping others born with Hypospadias. As a psychologist, he says that if you follow Rosenthal and Baskin’s logic and look at hypospadias as incomplete masculinization of the genitals…

DEVORE:… the same thing probably happened in the brain in the areas where there’s sexual differentiation of the brain. Now it doesn’t make a person gay, lesbian, bisexual or transsexual but it certainly makes it easier for that person to be any of those things.

AHEARN: There’s no peer-reviewed scientific research to back up Devore’s claim about sexual orientation and hypospadias. However, the Hypospadias and Epispadias Association – a group, which works to raise awareness about these two similar genital conditions - conducted an online survey of roughly 700 men – with hypospadias and without. The survey found that men with hypospadias were 15 percent more likely to describe themselves as gay.

I told Devore about Tyrone Hayes – the biologist at Berkeley with the homosexual and feminized frogs – and asked him what he thought about those findings in relation to people. He said the connection makes sense…

Tyrone Hayes' at work in his lab in Berkeley (Photo: Ashley Ahearn)

DEVORE: But we can’t prove it because we can’t experiment on human beings. We can certainly look at population models and say this looks like it’s pretty closely related, we probably should take some actions here to see if it is, but we can’t say that we don’t know the whole story yet.

AHEARN: Devore says there's a whole lot more to someone's sexual orientation than the chemicals they may have been exposed to during development.

DEVORE: This isn’t just about where you stick your things. This isn’t just about how you get good sensation in your body. This is about who you fall in love with. This is about a whole complex set of social factors.

CURWOOD: Clinical psychologist Dr. Tiger Howard Devore there, ending that excerpt from Ashley Ahearn’s report on the effects of endocrine disrupting chemicals on the development of males. There’s more on our website, LOE.org.



A study that looks at hypospadias and endocrine disruptors.

Hypospadias and Epispadias Association

Dr. Tiger Howard Devore

Tyrone Hayes' research: Hermaphroditic, demasculinized frogs after exposure to the herbicide atrazine at low ecologically relevant doses

Tyrone Hayes' research: Herbicides: Feminization of male frogs in the wild


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