Paralysis Through Analysis

Friday, November 04, 2005

Endocrine Disruptors and Gender Ratios

In October of 2005, a group of scientists published a journal article about an Aamjiwnaang First Nation (Native American) community in Ontario. The community is located near an industrial center and in recent years has been encountering very disturbing sex ratios. In the past ten years, 41.2% of all births have been male children and in the past five years, this number has decreased to 34.8%. The scientists’ study set out to find if endocrine disrupting materials produced in the industrial plants were influencing the sex ratios.

The study included surveys, environmental analysis and both a Canadian and First Nation control group. In the end, the data collected revealed that the sex ration of the community had remained relatively constant until 1993, at which point it began to fall at a steady rate.

While it is certainly possible that these results were caused by other factors, such as nutrition, parental age, and illness, endocrine disruptors appear to be a reasonable cause for the sudden change in the community’s sex ratio. Though the sex of the fetus is determined at conception, parental hormone levels have been determined to be partially responsible for determining the birth ratio. Because endocrine disrupting chemicals can “mimic” hormones, they can have the same effect as naturally occurring chemicals. More importantly, the study found that the area of the community had been known to contain EDC contamination:

“Numerous studies indicate that wildlife populations in the Great Lakes area are being adversely affected by the level of contamination, and that evidence from wildlife research could be used as a sentinel for human health effects (Fox 2001). In the Great Lakes area close to the Aamjiwnaang reserve, fish with intersex gonads (both male and female) have been reported in Lake St. Clair (Kavanagh et al. 2004). There is also ongoing research in the St. Clair River Area of Concern region of the Great Lakes that is documenting reduced hatching success and altered sexual development in turtles as well as changes in the sex ratios of birds (Environment Canada Canadian Wildlife Service 2003)”.

If the only condition that caused the gender ration of the Aamjiwnaang to change so dramatically was industrial waste, other industrial towns may soon face similar problems. Though it is impossible to pinpoint the issue to Endocrine Disrupting Chemicals, the possibility that they may be responsible does constitute a cause for concern. While more studies must still be conducted to prove this theory, action ought to be taken to clean up industrial communities, not only because of their risk of EDC exposure, but also because of the general health hazards they pose.


At 7:56 AM, Blogger Rod said...

You have a great blog here! I have a texas turkey hunting site. You can find everything about texas turkey hunting as well as info hunting rifles, scopes, bows, feeders, stands and more. Check it out when you can :)

At 7:26 PM, Blogger Winston Wade (Gamer) said...

If I understand the hypothesis correctly, wouldn't this imply a number of children with XY chromosomes being born female? Or is their a higher rate of miscarriage among male fetuses due to conflicting chemical signalling?

At 9:27 PM, Blogger Bonnie said...

Your first postulate is absolutely wrong. Your second is one conclusion supported by this study.
The other factor is that parental endogenous hormone levels (which can be affected by the amount of endocrine disruptors in the body, given that endocrine disruptors can act as hormones) at the time of conception can affect the sex of the formed zygote. That is, parents with higher levels of estrogen and antiandrogens may be more likely to form a diploid that is XX than to form a diploid that is XY. This is another conclusion supported by the study. Of course, no one pretends that either of these conclusions is proven, but there is support here to warrant alarm and signal a need for further study.

At 12:48 PM, Blogger Winston Wade (Gamer) said...

Thanks, Bonnie. My background is engineering, not biology, so the otherwise obvious isn't so much so from my perspective. Consider me set straight.

At 4:41 PM, Blogger Bonnie said...

Thanks for your question...and kudos to you for taking an interest and following up.


Post a Comment

<< Home