Banned decades ago, PCBs still posing threat to wildlife

Banned decades ago, PCBs still posingthreat to wildlife13 December 2021, by Michael Casey

A loon swims on Squam Lake, Friday, June 25, 2021, inHolderness, N.H. Researchers in New Hampshire havelong struggled to understand why loon numbers havestagnated on the lake, despite a robust effort to protectthem. They are investigating whether contamination fromPCBs could be impacting reproduction and believe oillaced with the chemicals was used on nearby dirt roadsdecades ago. Credit: AP Photo/Elise Amendola

Navigating her boat toward a wooden platformfloating in an idyllic New Hampshire lake where"On Golden Pond" was filmed, biologist TiffanyGrade spotted what she had feared.

An olive brown loon's egg with black speckles wassitting on an nest, abandoned by its parents andwith no chance to hatch. Gently scooping it up withgloved hands, Grade placed the egg in a zip lockbag and packed it into a cooler.

The egg was sent to a lab in Canada to test forchemicals including Polychlorinated biphenyls, orPCBs, that have been found in other Squam Lakeloon eggs, the fish there and a tributary of the lake.

Grade is investigating the potential link betweenPCBs and population declines of the fish-eating

birds known for their sharp beaks, black and whitespeckled backs, iridescent greenish heads andhaunting calls.

"These are chemical contaminants," said Grade,who works for the Loon Preservation Committee inNew Hampshire. "We don't know what the effectsare but some of those eggs are at levels that haveexceeded (those) known to cause health andreproductive problems in other bird species ... Thatis enough to make us worried and dig into it more."

The presence of PCBs on a lake in the shadow ofthe White Mountains demonstrates how these heat-resistant chemicals once used widely in electricalequipment and other industrial applicationscontinue to pose a threat to wildlife more than fourdecades after being banned in the United States.

A sign designating a "Loon Nesting Sanctuary" floats onSquam Lake, Friday, June 25, 2021, in Holderness, N.H.Researchers in New Hampshire have long struggled tounderstand why loon numbers have stagnated on thelake, despite a robust effort to protect them. They areinvestigating whether contamination from PCBs could beimpacting reproduction and believe oil laced with thechemicals was used on nearby dirt roads decades ago.Credit: AP Photo/Elise Amendola

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PCBs, a class of more than 200 chemicals used foralmost 50 years, have been found in wildlife aroundthe world, such as Icelandic killer whales,shorebirds along the Great Lakes and bottlenosedolphins along the East Coast and in theMediterranean. Scientists have found they canmake some animals more vulnerable to diseasesincluding cancer and can disrupt growth, energyproduction and reproduction.

"There is five decades of research showing thatPCBs have had health impacts on both wildlife andhumans," said Keith Grasman, a biology professorat Calvin University in Michigan who has studiedpollutant impacts on birds in the Great Lakes andother places. "While their concentrations in theenvironment have declined in many situations ... westill see issues with these legacy compounds."

In New York, researchers found chickadees andsong sparrows that ate insects contaminated withPCBs along the Hudson River sounded a bitdifferent than ones in uncontaminated areas in theAdirondacks. Cornell University researchers believethe PCBs interfere with development in part of thebird's brain responsible for song and could haveconsequences for breeding.

A loon egg sits in a floating nest at the Loon NestingSanctuary on Squam Lake, Friday, June 25, 2021, inHolderness, N.H. Researchers in New Hampshire havelong struggled to understand why loon numbers havestagnated on the lake, despite a robust effort to protectthem. They are investigating whether contamination fromPCBs could be impacting reproduction and believe oillaced with the chemicals was used on nearby dirt roads

decades ago. Credit: AP Photo/Elise Amendola

PCBs continue to move up the food chain, withanimals at the top often harboring the highestconcentrations.

The Marine Mammal Center responds to 800stranded marine mammals yearly along 600 miles(965 kilometers) of California coast. A 2020 studyof stranded adult sea lions concluded that PCBsand DDT, which also was banned decades ago, arecontributing to cancer rates as high as 23%.

"That rate of cancer is mostly unprecedented inwildlife," said Cara Field, medical director of thecenter, adding that the disease caused a "completesystemic breakdown" in the animals and theirblubber had much higher levels of PCBs than thosewithout cancer.

Fish-eating birds, too, have suffered from exposureto PCBs.

In recent decades, studies at a Superfund site inMassachusetts, on islands in the New York harborand at contaminated sites in the Great Lakes foundsignificant levels of PCBs in common terns,endangered Roseate terns, Caspian terns, herringgulls and double-crested cormorants. Scientistsfound that PCBs, sometimes combined with otherchemicals, suppressed the birds' immune system,increased infertility and reduced chick survivalcompared to unpolluted sites.

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Biologist Tiffany Grade collects a non-viable loon eggfrom a floating nest on Squam Lake, Friday, June 25,2021, in Holderness, N.H. Grade is studying the impactPCBs are having on loons and will examine the egg forpossible PCB contamination. Researchers in NewHampshire have long struggled to understand why loonnumbers have stagnated on the lake, despite a robusteffort to protect them. Credit: AP Photo/Elise Amendola

At Squam Lake—site for the 1981 movie starringHenry Fonda and Katharine Hepburn and now atourist destination—Grade and colleagues at theLoon Preservation Committee, which has beenworking since 1975 to protect New Hampshire'sloons, want to know why they are producing so fewchicks.

The population crashed between 2004 and2005—from 16 pairs to nine—and has been slow torecover. This year, there were only 14 pairsrecorded on the lake, c ompared to 312 in otherparts of the state. Only three chicks survived—stillless than half the productivity of other NewHampshire lakes.

The committee, which began testing Squam Lakeeggs in 2007, found PCBs and other contaminantswere up to six times higher than eggs testedelsewhere in New Hampshire, Maine and NewYork. The nonprofit also found PCBs in a tributaryemptying into the lake and in their crayfish, whichled to a theory that PCB-laced oil used to controldust on dirt roads decades ago may have reachedthe waterways.

Biologist Tiffany Grade holds a non-viable loon eggcollected from a floating nest on Squam Lake, Friday,June 25, 2021, in Holderness, N.H. Grade is studying theimpact PCBs are having on loons and will examine theegg for possible PCB contamination. Researchers in NewHampshire have long struggled to understand why loonnumbers have stagnated on the lake, despite a robusteffort to protect them. Credit: AP Photo/Elise Amendola

The loon egg contamination prompted the state totest the lake's smallmouth bass and yellow perch.And high PCBs levels led to a 2020 health advisorylimiting the amounts of fish eaten by anglers.

"We would not have suspected that Squam Lakewould have been a place in which this was aproblem," said Ted Diers, administrator of thestate's Watershed Management Bureau. "There isno industry. It just opens up lots of questions thatwe truly can't answer at this point."

Loons, a threatened species in New Hampshire,face myriad challenges.

Shore-prowling predators such as raccoons raidtheir nests. Territorial disputes kill the birds.Ingesting lead fishing tackle poisons them. Theirnest sites lose out to development. And a warmingclimate can overheat loons and flood their nests.

Researchers have also found PFAS fire retardants,the pesticide chlordane and other chemicals in looneggs. But PCBs were in the greatestconcentrations, although Grade says more work's

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needed to assess what's causing the bird's poorreproductive outcomes.

Biologist Tiffany Grade looks for loon eggs that may havefallen into the water from a floating nest on Squam Lake,Friday, June 25, 2021, in Holderness, N.H. Grade isstudying the impact PCB's are having on loons, andexamines their eggs for possible PCB contamination.Researchers in New Hampshire have long struggled tounderstand why loon numbers have stagnated on thelake, despite a robust effort to protect them. Credit: APPhoto/Elise Amendola

"Contaminants aren't the only thing these loons aredealing with. They are dealing with a lot," she said."That is not easy to separate. It is a lot easier if youare sitting a bird down in the lab and dosing it withcontaminants and seeing what happens. Thatobviously is not what we are doing."

Anne Kuhn, a U.S. Environmental ProtectionAgency scientist who has researched contaminantsin wildlife, agreed it could be a challenge to teaseout the impact of PCBs on Squam Lake loons.

Her own work found that mercury, often from coal-fired power plants, combined with shorelinedevelopment and human activities in NewHampshire lakes, were hurting loon populations.But mercury alone was not.

Similarly, said EPA research biologist Diane Nacci,it could be that PCBs and other chemicals workingtogether are causing the problem

Biologist Tiffany Grade carries a cooler containing a non-viable loon egg collected from Squam Lake, Friday, June25, 2021, in Holderness, N.H. Grade is studying theimpact PCB's are having on loons, and will examine theegg for possible PCB contamination. Researchers in NewHampshire have long struggled to understand why loonnumbers have stagnated on the lake, despite a robusteffort to protect them. Credit: AP Photo/Elise Amendola

Biologist Tiffany Grade measures a non-viable loon eggcollected from Squam Lake, Friday, June 25, 2021, inHolderness, N.H. Grade is studying the impact PCB's arehaving on loons, and will examine the egg for possiblePCB contamination. Researchers in New Hampshirehave long struggled to understand why loon numbershave stagnated on the lake, despite a robust effort toprotect them. Credit: AP Photo/Elise Amendola

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A loon takes flight on Squam Lake, Friday, June 25,2021, in Holderness, N.H. Researchers in NewHampshire have long struggled to understand why loonnumbers have stagnated on the lake, despite a robusteffort to protect them. They are investigating whethercontamination from PCBs could be the culprit and believeoil laced with the chemicals was used on nearby dirtroads decades ago. Credit: AP Photo/Elise Amendola

Biologist Tiffany Grade writes notes as she examines anon-viable loon egg collected from Squam Lake, Friday,June 25, 2021, in Holderness, N.H. Grade is studying theimpact that PCB's are having on loons, and will test theegg for possible PCB contamination. Researchers in NewHampshire have long struggled to understand why loonnumbers on the lake have stagnated, despite a robusteffort to protect them. Credit: AP Photo/Elise Amendola

"Any one stressor might not be enough to affect

reproduction in loons but together that might be thestraw that broke the camel's back," Nacci said.

For now, Grade collects abandoned eggs onSquam and other New Hampshire lakes and teststhem for contaminants, searching for elusiveanswers that could help the loons survive. "Theyare an absolutely charismatic birds," she said. "It'shard to imagine any New Hampshire lake withoutloons."

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APA citation: Banned decades ago, PCBs still posing threat to wildlife (2021, December 13) retrieved 11May 2022 from https://phys.org/news/2021-12-decades-pcbs-posing-threat-wildlife.html

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