Drug pol­lu­tion con­cen­trates in stream bugs, passes to preda­tors in water, study says

An­i­mals that eat bugs in or near streams at risk of be­ing dosed with phar­ma­ceu­ti­cals

The Daily News Egypt - - Science -

Sixty-nine phar­ma­ceu­ti­cal com­pounds have been de­tected in stream in­sects, some at con­cen­tra­tions that may threaten an­i­mals which feed on them, such as trout and platy­pus. When these in­sects emerge as fly­ing adults, they can pass drugs to spiders, birds, bats, and other stream­side for­agers, ac­cord­ing to a new study con­ducted by an in­ter­na­tional team of re­searchers.

Ac­cord­ing to the find­ings of the study which was pub­lished re­cently in Na­ture Com­mu­ni­ca­tions jour­nal, phar­ma­ceu­ti­cal pol­lu­tion is present in sur­face wa­ters glob­ally. Drugs en­ter the en­vi­ron­ment be­cause most waste­water treat­ment fa­cil­i­ties are not equipped to re­move them from sewage. Sep­tic tanks, ag­ing pipes, and sewer over­flows con­trib­ute to the prob­lem.

“Stream life is swim­ming in a mix­ture of phar­ma­ceu­ti­cals. Our study is the first to show that this chronic drug pol­lu­tion can con­cen­trate in aquatic in­sects and move up food webs, in some cases ex­pos­ing top preda­tors to ther­a­peu­ti­cally-rel­e­vant doses,” said Emma Rosi, an aquatic ecol­o­gist at the Cary In­sti­tute of Ecosys­tem Stud­ies and a co-au­thor of the pa­per.

In or­der to get to their find­ings, the team sam­pled six streams in Mel­bourne,Aus­tralia for 98 phar­ma­ceu­ti­cal com­pounds—the most ex­haus­tive screen­ing to date. Phar­ma­ceu­ti­cals mea­sured in­cluded com­mon drugs like an­tibi­otics, an­tide­pres­sants, an­ti­his­tamines, and NSAIDs.

Sites that were in­ves­ti­gated in the study were se­lected along a gra­di­ent of waste­water con­tam­i­na­tion which in­cluded a site down­stream of a waste­water treat­ment plant, and a site in a na­tional park.Aquatic in­sects and ri­par­ian spiders were col­lected.

“We fo­cused on ri­par­ian spiders be­cause they build their webs over streams and feed on adult aquatic in­sects as they emerge from the water,” ac­cord­ing to Erinn Richmond, a fresh­wa­ter ecol­o­gist at Monash Uni­ver­sity in Aus­tralia and lead study au­thor.

Ac­cord­ing to the pa­per, tis­sue analy­ses de­tected up to 69 dif­fer­ent phar­ma­ceu­ti­cal com­pounds in aquatic in­sects, and up to 66 com­pounds in ri­par­ian spiders. Drug con­cen­tra­tions were the high­est in in­ver­te­brates col­lected down­stream of waste­water treat­ment fa­cil­i­ties,or in heav­ily pop­u­lated ar­eas, with po­ten­tial sep­tic tank leak­age. On av­er­age, phar­ma­ceu­ti­cal con­cen­tra­tions at these sites were 10 to 100 times higher than less con­tam­i­nated sites.

The mis­sion of analysing the in­sect and spi­der sam­ples was the work of co-au­thor Jerker Fick, a chemist at Umeå Uni­ver­sity in Swe­den. He said that “In­sect tis­sues had drug con­cen­tra­tions that were or­ders of mag­ni­tude higher than con­cen­tra­tions mea­sured in sur­face wa­ters.We also found a di­verse suite of drugs in spiders, in­di­cat­ing that drugs are passed from the water to prey to preda­tor, thereby ex­pos­ing other an­i­mals in the food web to drugs.” “Phar­ma­ceu­ti­cals were present in ev­ery in­sect and spi­der we tested— in­clud­ing those col­lected in Dan­de­nong Ranges Na­tional Park,” Richmond notes. “Even this seem­ingly pris­tine site was con­tam­i­nated, likely be­cause peo­ple live in the park’s drainage area and visit the park,” he added.

In the streams stud­ied, platy­pus and brown trout also feed on aquatic in­sects. By pair­ing con­cen­tra­tions of phar­ma­ceu­ti­cals found in stream in­sects with known di­etary needs of platy­pus and trout, the team was able to es­ti­mate their drug ex­po­sure.

Emma Rosi, an aquatic ecol­o­gist at the Cary In­sti­tute of Ecosys­tem Stud­ies ex­plained that “a platy­pus liv­ing in a creek re­ceiv­ing treated waste­water ef­flu­ent could re­ceive the equiv­a­lent of half of a rec­om­mended hu­man dose of an­tide­pres­sants ev­ery day, just by eat­ing its nor­mal diet of stream in­sects.This in­take is likely to have bi­o­log­i­cal ef­fects.”

The cad­dis­fly, a glob­ally com­mon aquatic in­sect, was among those tested in this study. Richmond says,“Sim­i­lar in­sects are found in fresh­wa­ters all over the world.This isn’t a prob­lem spe­cific to Aus­tralia; it’s rep­re­sen­ta­tive of what’s likely hap­pen­ing wher­ever peo­ple take drugs.And it’s likely an un­der­es­ti­mate.We only tested for 98 phar­ma­ceu­ti­cal com­pounds—there are thou­sands in cir­cu­la­tion.”

“Phar­ma­ceu­ti­cal use is in­creas­ing world­wide.It’s clear that the drugs we take are en­ter­ing fresh­wa­ters and be­ing passed up the food web.We don’t know the eco­log­i­cal con­se­quences of ex­po­sure to this pol­lu­tion.What does it mean to be a platy­pus or trout with more than 60 drugs in your tis­sues? Are there syn­er­gis­tic ef­fects? More re­search is needed on the ex­tent of food web con­tam­i­na­tion and the ef­fects of these com­pounds on fish and wildlife,” Rosi con­cludes.

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