Intro to Frog Toxicology and Environmental Health

It is amazing how some species can warn humans about environmental hazards that are naturally occurring or are the effects of man-made toxins released into the Earth. Frogs continue to be a superstar in our ecosystem because of their permeable skin. As part of their survival, water is needed. If the water supply is contaminated, even in small traces, researchers and scientists will take notice because frogs will decline in population and/or become malformed physically or internally.  

 As the human population continues to grow and the high demand to produce food crops such as corn and grain, the US farmers are using cheap and effective herbicides to keep their crops from suffocating by weed overgrowth. Over 60 million pounds of one specific herbicide used in the US annually is Atrazine. Atrazine is an endocrine disrupter and teratogen which means they cause abnormalities related to hormone and embryonic growth (Cunningham & Cunningham, 2012). Yet, years of research and hundreds of repeated experiments have concluded that atrazine "has long been known to disrupt endocrine hormone functions in mammals, resulting in spontaneous abortions, low birth weights, and neurological disorders" (Cunningham & Cunningham, 2012). The only way researchers knew about this alarming cause for concern was because there was evidence of malformed frogs and reproductive changes within male frogs found in the water where atrazine was being used. 

The amount of Atrazine used in water to see any changes in the frogs is less than 0.1 ppb (parts per billion) which is 30 times less allowed in tap water (Hayes, 2003). If such a low dose can alter male frogs into hermaphrodites, it is shocking that the chemical is still allowed to be used. Atrazine is linked to the altering of the frog population where atrazine is being used. The more frogs that are turning into hermaphrodites the more hazardous it is to the frog population because they only produce male frogs. This is one of the direct results in the decline of the female frog population. Atrazine is also linked to malformation in frogs. The result is of further decline of frog populations because they are unable to escape from natural predators.

One activist, biologist, researcher and professor whom has spent a good portion of his career dedicated to amphibians is Tyrone Hayes from the University of California. He has been credited for his work in numerous publications that proves the affects that atrazine has on amphibians, specifically frogs. Though many will try and discredit his work, specifically the atrazine manufacture, but it is well known that those who produce a product will never admit to the hazards they are creating to the environment. Hayes published work in the Environmental Health Perspectives which documents the findings of his study confirming the dangerous environmental effects of atrazine. 

On the flip side, ecological diseases can just be has harmful as endocrine disrupters. Chytridomycosis aka the chytrid fungus is eliminating about 2,000 of the 6,000 amphibian species, mostly frogs (Cunningham & Cunningham, 2012). The chytrid "fungus is advancing 14 to 62 miles per year on every continent but Asia" according to PBS.org. As the fungus lives in water and moist areas, the rate of travel is quite fast taking into account that temperatures above 28 degrees Celsius kill the fungus (Cunningham & Cunningham, 2012). 

Sources:

Cunningham, W., & Cunningham, M. A. (2012). Environmental science a global concern. (12 ed., pp. 159-167). New York, New York: McGraw-Hill.

Hayes, T. (2003). Atrazine-induced hermaphroditism at 0.1 ppb in american leopard frogs (rana pipiens): Laboratory and field evidence. In Environmental Health Perspectives (4 ed., Vol. 111, pp. 568-575). Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1241446/pdf/ehp0111-000568.pdf

PBS. (2009). Frogs: The thin green line a world without amphibians. Retrieved from http://www.pbs.org/wnet/nature/episodes/frogs-the-thin-green-line/a-world-without-amphibians/4852/