Tracking Pollutants in the Body

Charles Tyler  and his group of scientists have genetically modified zebrafish that glow green to help illuminate what pollutants do inside the body.

Tyler and his team of scientists exposed the zebrafish to varying levels of endocrine disruptors (chemicals known to affect the hormone estrogen) including nonylphenol which is present in paints and industrial detergents and bisphenol A which is a component of many plastics.

These substances have become common freshwater pollutants that are connected to various reproductive problems in both people and animals. Previous research has shown that by mimicking the actions of sexual hormones, the chemicals cause fish to change gender, and in people, endocrine disruptors have been associated with lower sperm counts and breast and testicular cancers.

Yet scientists have had difficulty tracking what endocrine disruptors do inside a person or an animal's body. So Tyler and his colleagues genetically engineered zebrafish to glow where an endocrine-disrupting chemical is present, and therefore show where it may be harming the body.

The researchers exposed the fish to different endrocrine disruptors at varying concentrations, and then used a microscope to see which of the fish's organs glowed, and thus responded to the chemicals.

The data should help identify to what extent the chemicals affect various tissues and organs in the body.

Although it's been thought that these chemicals only impact the liver, testes, or ovaries, the chemicals also illuminated other parts of the fish's anatomy, including its eyes, skeletal muscles, and parts of the brain.  However,  the impact of endocrine disruptors to these parts of the body are unknown.

For now, the observation of fluorescent technology is limited to fish younger than six days old, because after that their skin develops pigmentation that interferes with viewing the fluorescence.

In the future, Tyler hopes to breed the zebrafish with a strain that lacks pigment in the skin which would allow the team to observe the fluorescent reactions in adult fish as well.


Because the article did not provide a link to the research findings of Tyler and his team, I am still left with multiple questions:
What evidence is there that supports the author's claim that endocrine disruptors have been associated with lower sperm counts and breast and testicular cancers?
Although this experiment was a great start for studying the effects of pollutants, will future models for this experiment include test subjects that are more similar to humans?
How do the pollutants enter the bodies of the fish? (Are they ingested, are they absorbed through the skin, etc?)
Does the mode in which the pollutant enters the body change it's affects on certain organs and tissues? (For example, do the affects of the pollutant vary depending on whether it is ingested or if it is inhaled?)
Do pollutants enter the body of a fish and the body of a human using different modes? (For example, fish absorb the pollutants through their skin while humans ingest the pollutants.)
If the two previous questions were found to be true, would the validity of the experiment in this article be compromised seeing as the affects of the endocrine disruptors might be too different on each organism to predict any correlation between the data collected from the zebrafish and possible affects on humans.