by Shannon Smith Houle
Concordia biology professor Sylvia Ruby has been in the news, notably
in the current issue of Canadian Geographic magazine. Thats
because her latest study, published in June, found a link between a common
weed killer, atrazine, and reproductive abnormalities in frogs.
The findings suggest that atrazine may be one cause of declining
amphibian populations, explained Ruby in an interview.
Atrazine is used extensively in North America, especially on corn, but
its safety has been the subject of some controversy and it is banned in
several European countries, including Denmark and Italy.
Dr. Ruby, a reproductive toxicologist, had been investigating several
chemicals which could be having an effect on the local frogs in the St.
Lawrence water system. One was atrazine, and it is found in Quebec
water in high concentrations.
Frog populations have been declining worldwide, and McGill researchers
have looked at local frogs with abnormalities, especially of the limbs.
Ruby looked specifically at the reproductive system.
During a critical period of development called differentiation, which
lasts only six to seven days in tadpoles, the sexual organs develop into
testes or ovaries. The process is regulated by hormones. This is when
atrazine has its effect.
When tadpoles are exposed to atrazine at that stage, it will affect
their reproductive system for life, Ruby explained.
Her study found that the testes of tadpoles exposed to atrazine were smaller,
and showed structural changes. A previous study by Ruby found structural
changes in ovaries as well.
Atrazine may also be having an effect on humans.
Like tadpoles, humans also undergo differentiation, though over a longer
period of time, and in utero. Some researchers think Rubys results
might predict the effects of atrazine in humans.
Given the similarities between the developmental process in amphibians
and mammals, including humans, the opportunity for extrapolation is quite
The results are worrisome. Previous research concluded that 21 micrograms
of atrazine per litre of water will not have any ecological effect. But
this is exactly the concentration Ruby used.
Despite the findings, Ruby isnt making any suggestions about what
should be done about them. The Environmental Protection Agency in the
U.S., and Canadian provincial agriculture ministries and Health Canada
all regulate the use of and safety standards involving atrazine.
Take my results, and let the regulators decide based on them,
Ruby said. I do the science.
Since her results were published in Environmental Toxicology and Chemistry
in June, Ruby has been in high demand. She was invited to present her
work to the EPA this summer, and her work has been featured in several
However, she isnt keeping all the credit for herself. The research
was done in collaboration with researchers Michel Fournier and Pauline
Brousseau at the Institut National de Recherche Scientifique (INRS) which
is associated with UQAM, and Concordia graduate student Luz Taverna-Mendoza.
Whats interesting is that graduate students in the [Biology]
Department at the masters level are capable of doing publishable
research in the top journals, she said.
And of course, there are the frogs. I just love tadpoles,