The U.S. Environmental Protection Agency acknowledged in a 76-page report to Congress this week that several information gaps about algal toxins are complicating efforts to keep them out of the public water supply.

Those gaps are as far-reaching and nebulous as climate change. But they also get to the heart of the agency’s decision to focus most of its research to date on microcystin-LR, the most common sub-species of western Lake Erie’s dominant form of harmful algae, a cyanobacteria called microcystis.

Microcystis is the main, but not the only, producer of the general class of toxins known as microcystin.

The report, prompted by a bill U.S. Rep. Bob Latta (R., Bowling Green) pushed through Congress in response to last year’s Toledo water crisis, now claims there are more than 100 known varieties of microcystin.

That’s up from 80 known to exist in 2014, and more than twice the number identified when the Geneva-based World Health Organization established the planet’s first drinking water advisory for that toxin in 1998.

At least four of them were in Toledo’s tap water when it was temporarily fouled by toxins in August, 2014. But nearly all of the scientific research funded to date has been on microcystin-LR.

In May, when the U.S. EPA released plans for America’s first advisory on that toxin, Peter Grevatt, director of the agency’s groundwater and drinking water office, said funding constraints slowed efforts to research other varieties. In its new report, the agency acknowledged that potential health risks from exposure to mixtures of microcystin varieties, or cogeners, are unknown.

“Thus, additional research is needed to understand the human health impacts of the other cogeners, both existing and emerging, as new cogeners continue to be isolated and identified,” the report said.

Among other things, the agency noted a need to better understand how water-treatment plant technology can be used to remove the toxins.

That view was echoed by Steve Via, American Water Works Association regulatory affairs manager, who urged the agency to “look beyond microcystin-LR” in comments he submitted during a Sept. 16 agency webinar.

The assumption that all varieties of microcystin have equal effects on the body “might not prove valid in the long haul,” he stated.

Microcystin-LR attacks the liver and central nervous system. At least one other variety is believed to attack the brain and has been linked to Alzheimer’s disease, according to previous Blade interviews.

Beth Messer, assistant chief of the Ohio EPA’s drinking and ground waters division, said during the webinar that additional research is needed in all microcystin variants.

She said Ohio supports continued expansion of remote sensing data to track algae, including efforts undertaken by NOAA and NASA to monitor it from the air. She also said the agency supports use of aircraft or drones.

In its report, the U.S. EPA said the prevalence and duration of harmful algal blooms is “rapidly expanding in the United States and worldwide.” It cited nutrient loading and climate change as factors.

“This initial plan is a first step in the development of a comprehensive, long-term strategy for assessing and managing the risks of algal toxins impacting our public drinking water,” Mr. Latta said Thursday.

First Published November 20, 2015, 5:00 a.m.