SUGARLOAF TWP. – Megan Schall grew up fishing and kayaking on the Susquehanna River, but gained deeper insight about the river when she started collecting smallmouth bass as a graduate student six years ago.

“What surprised me most (was) some of these fish had open sores, some had raised bumps, some had black spots … not quite what you would expect,” Schall said Thursday at Penn State Hazleton during a public lecture on everyday poisons in waterways.

The deformities and early mortality that scientists started noticing among bass more than a decade ago didn’t bode well with the anglers who buoy the economy while catching bass. The implications also were grim for organisms lower on the food web and for 6 million people who drink water from the Susquehanna River.

Schall, an assistant biology professor, joined a study with state and federal fish and wildlife agencies that looked at the range of possible causes for the ailments striking bass.

The suspects included parasites, pathogens, chemicals, metals, pharmaceuticals and runoff from industries and farms.

Some chemicals such as DDT and PCBs, recognized as hazards and banned decades ago, still persist in water because of the time they take to degrade.

Major incidents, such as a spill of lye that Schall studied, quickly kill downstream.

But substances that don’t kill might cause insidious effects such as disrupting endocrine systems that regulate growth, behavior and reproduction. Male smallmouth bass, for example, developed precursors of female egg cells in their testes.

Rarely, Schall said, are symptoms linked to a single cause or source.

She mentioned one study of 38 streams that found 400 chemicals and another survey of 199 water sights that tested positive for 38 endocrine disrupters.

In such a stew, interactions between chemicals might heighten or lessen effects in ways difficult even for scientists to sort out.

Schall said she could have talked for hours about individual contaminants.

Instead, she focused on a few.

Atrozine, a herbicide, has been shown to cause adverse effects in fish and frogs.

Dioxins, byproducts of burning plastics, join DDT and PCBs on the Dirty Dozen list of the worst, longest-lasting pollutants.

Alert consumers can avoid buying products with triclosan, an antibacterial ingredient in soap and toothpaste that has created resistant strains of bacteria.

But how do diabetics stop using metformin, which regulates their blood sugar but has disrupted endocrine systems and reproductive systems in minnows?

With so many possible contaminants – Schall said scientists have identified 1,000 endocrine disruptors so far – and more being developed, how can sewage treatment plants keep pace?

She outlined strategies for anyone to follow:

■ Consider the impact that a substance you use will have on life in the future.

■ Know as much as possible about the water you drink. Read reports from your municipal water supplier or your well tests.

■ Evaluate bottled water, including components of plastic in the bottle, test results of the water source or what the filter removes or doesn’t remove.

■ Be aware of advisories about eating fish. On the Susquehanna River in Luzerne, Lackawanna, Wyoming, Columbia, Northumberland and Montour counties this year, the Pennsylvania Fish and Boat Commission recommends eating no more than two meals a month of smallmouth bass because of mercury contamination and advises a limit of one meal a month on walleye and channel catfish because of PCBs.

“It’s not meant to scare you. It’s meant to make you think,” Schall said. “We can all be part of the solution to protect our water resources.”

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