Mark Benfield peered into the tea-colored water inside the specimen jar. Skimming the Mississippi River near LSU produced the usual results — pollen, twigs, kernels of corn.

The collection site is downstream of the Baton Rouge industrial district and the port, as well as the wastewater and stormwater outfalls.

But Benfield focused on some small white specks — the small beads and tiny strands of plastic that litter the Mississippi River.

His team of LSU scientists has been able to able to quantify much of this particular pollution on the Mississippi. For example, they've found far higher concentrations of pollutants in New Orleans relative to Baton Rouge. Their working theory is that riverside plants are spilling minute plastic products into the river, though they lack the data to finger any particular site.

Microplastic is created when bits of bottles, bags and other material break down. Think of a guy in Minnesota with a to-go coffee, Benfield began. The customer finishes his drink and tosses the cup in the gutter. The cup gets churned up by the wastewater system, then by the ships on the Mississippi. By the time it reaches the monitoring station at LSU, it's reduced to little particles of plastic, but those small amounts can wreak havoc on wildlife.

From the microbeads in skin creams to packaging material, eventually many industrial and consumer products degrade into microplastics, defined as bits of plastic less than 5 millimeters across. Due to its chemical composition, plastic is a "sponge" for dangerous materials, like those found in pesticides, Benfield said.

Not-so-bright fish can't distinguish between blobs of plastic and the zooplankton they'd normally eat. Consuming plastic is bad for a number of reasons, some more obvious than others. It blocks the digestive tract and gives a false sense of fullness. But research also has suggested there are insidious problems for the entire food chain.

The chemicals get magnified as progressively bigger animals eat the fish that originally consumed the contaminated plastic, Benfield said. 

The team studying microplastic pollution recently penned a paper originally titled "The Invisible Problem." 

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It has been accepted for publication and looks at microplastic in the northern Gulf of Mexico. They found relatively high concentrations of the material, comparable to what has been found in similar bodies of water across the globe. One reason could be that they collected samples near the bird's foot delta, where Mississippi flows into the Gulf, the paper speculates.

The authors hope more work beyond that project — partially funded by Louisiana Sea Grant — will be forthcoming, looking not only at the Gulf, but its estuaries and river systems.

One issue the LSU scientists freely acknowledge is that there's simply a fair amount of unknowns surrounding their research.

For example, the chemicals that are attracted to plastics cause hormonal problems — at least, it does in amphibians. That means frogs with skewed maturation rates, unexpected sexual characteristics and even impotence.

Benfield, a professor at LSU's College of the Coast and Environment, wants to conduct further research on the effect of plastic pollution on humans. He's also submitting data to a friend who works with radioactive material to see if plastic is absorbing fallout, and what effect that may have.

The professor is joined in his research by oceanographer and statistician Matthew Kupchick.

He built the filtration device that pulls water from the river for analysis. Unlike other scientists, who have to get various permits and permissions to collect samples, you can skim for people's garbage without any oversight, Kupchick said. In addition to the pump, he pulls a net along the surface of the water to collect his samples.

When plastic is extracted, he can take it back to the lab to run through a spectrometer. The equipment helps scientists determine the composition of chemical compounds like plastic.

The team also had a third member, Rosana Di Mauro, who is currently studying plastic pollution off the Atlantic coast of South America. Benfield said he hopes to collaborate with her in the future — after all, the Gulf of Mexico eventually connects to the Atlantic.

Until then, he's comparing his research to colleagues' in Europe who are studying bodies of water like the Mediterranean Sea.

It's too soon to tell whether authorities there have taken helpful steps to curb plastic pollution, Benfield said. However, Europeans have been proactive about limiting plastic bags and encouraging recycling, he said.

Southeast Asia has typically been assumed to be the most plastic-polluting area of the world. Benfield, however, wondered if the Mississippi wouldn't be high on the list, if subject to more scrutiny.

Follow Steve Hardy on Twitter, @SteveRHardy.