Breath­ing diesel ex­haust in­duces DNA changes: study

Vancouver Sun - - WESTCOAST NEWS - PAMELA FAY­ER­MAN Sun health is­sues re­porter pfay­er­[email protected]­cou­ver­sun.com

Asth­mat­ics who in­haled diesel ex­haust fumes for two hours in a study booth didn’t just get itchy eyes and a headache while breath­ing in the pol­luted air.

They also ex­pe­ri­enced ef­fects on a mi­cro level as genes as­so­ci­ated with in­flam­ma­tory and ox­ida­tive stress pro­cesses were al­tered.

Those are the find­ings from five re­searchers at the Univer­sity of B.C. who put 16 asthma pa­tients in a cu­bi­cle, ex­pos­ing them — on sep­a­rate oc­ca­sions — to fil­tered air and diesel ex­haust and later com­par­ing blood sam­ples col­lected be­fore and after ex­po­sures.

Diesel ex­haust in­duced DNA changes but fil­tered air did not, ac­cord­ing to lead re­searcher Christo­pher Carl­sten, a respirol­o­gist and as­so­ciate pro­fes­sor in the di­vi­sion of res­pi­ra­tory medicine.

The study by the re­searchers at UBC and Van­cou­ver Coastal Health is pub­lished in the jour­nal Par­ti­cle and Fi­bre Tox­i­col­ogy. It showed that just two hours of ex­po­sure to diesel ex­haust fumes led to biological changes that meant some genes were switched on while oth­ers turned off. The air qual­ity dur­ing the diesel fume ex­po­sures is said to be com­pa­ra­ble to a Beijing high­way or shipping ports in B.C.

Carl­sten said study sub­jects aged 19 to 35 were each paid a to­tal of $600 for the three times they vis­ited the study lab. Since each visit was time-con­sum­ing be­cause of blood tests and other in­ves­ti­ga­tions re­quired, the hourly stipend given to the par­tic­i­pants prob­a­bly worked out to about $15 per hour, he said in re­sponse to ques­tions about why in­di­vid­u­als with asthma would want to breathe in pol­luted air for the sake of the ex­per­i­ment.

While some par­tic­i­pants ex­pe­ri­enced eye dis­com­fort and a mild headache, none be­came sick or re­quired med­i­ca­tion when ex­posed to the diesel air in the study, which was funded by grants from var­i­ous pub­licly funded re­search agen­cies.

“More im­por­tantly, we had no ev­i­dence that such sin­gle, brief ex­po­sures ex­ac­er­bate asthma in mild asth­mat­ics — which is why we were able to eth­i­cally per­form the study,” he said. “In fact, our stud­ies (in­clud­ing this one) re­peat­edly bear that out. All we see are sub-clin­i­cal changes which help us un­der­stand how air pol­lu­tion may be af­fect­ing health with­out ac­tu­ally hurt­ing any­one.”

He said the next step is for re­searchers to study how changes in gene ex­pres­sion from air pol­lu­tion af­fect the hu­man body over the long term, since the study shows genes may be vul­ner­a­ble to pol­lu­tion with­out pro­duc­ing any ob­vi­ous or im­me­di­ate symp­toms of ill health.

“Usu­ally when we look at the ef­fects of air pol­lu­tion, we mea­sure things that are clin­i­cally ob­vi­ous — air flow, blood pres­sure, heart rhythm,” Carl­sten said. “But asthma, higher blood pres­sure or ar­rhyth­mia might just be the grad­ual ac­cu­mu­la­tion of (gene) changes. So we’ve re­vealed a win­dow into how th­ese long-term prob­lems arise. We’re look­ing at changes deep un­der the hood.”

Ac­cord­ing to the provin­cial Min­istry of Health, an “in­tera­gency” group is work­ing on op­tions to ad­dress diesel emis­sions.

The re­search is timely be­cause the provin­cial Air­Care pro­gram has ended and en­vi­ron­men­tal ad­vo­cates are con­cerned about the im­pacts of older ve­hi­cles and diesel en­gines. Metro Van­cou­ver re­cently an­nounced it will en­force ex­ist­ing by­law pro­hi­bi­tions on diesel en­gines as of this month.

“Older non-road diesel en­gines that have lit­tle or no emis­sion con­trols are the main con­cern of the by­law. En­gines in ma­chines like ex­ca­va­tors, fork­lifts and gen­er­a­tors are ex­am­ples of those in­cluded in the by­law,” said Greg Moore, chair of the Metro Van­cou­ver board of direc­tors.

“Diesel en­gine ex­haust is a known car­cino­gen that is re­spon­si­ble for twothirds of the lifetime can­cer risk from air pol­lu­tion in our re­gion,” Moore said. “The pro­hi­bi­tions that come into ef­fect in 2015 are es­sen­tial to pro­tect hu­man health by re­duc­ing emis­sions of harm­ful diesel soot from in­dus­trial and con­struc­tion ma­chines.”

For more in­for­ma­tion about the by­laws, which carry stiff penal­ties (fines up to $200,000), call 604-4326200 or send an email to: non­road­[email protected]­cou­ver.org

DON ERHARDT/UBC FAC­ULTY OF MEDICINE

‘Asthma, higher blood pres­sure or ar­rhyth­mia might just be the grad­ual ac­cu­mu­la­tion of (gene) changes.’ says lead re­searcher Christo­pher Carl­sten.

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