Don’t leap to con­clu­sions on back­yard weed­killer wor­ries

Reg­u­la­tors have an eye on her­bi­cide Roundup but not all is as it seems, ex­plains Jan Davis

Mercury (Hobart) - - TALKING POINT - Jan Davis is an agribusi­ness con­sul­tant and for­mer chief ex­ec­u­tive of the Tas­ma­nian Farm­ers and Gra­ziers As­so­ci­a­tion.

A PIV­OTAL de­bate now un­der way in the Euro­pean par­lia­ment could re­voke the li­cence for the most widely used her­bi­cide in hu­man his­tory, with fate­ful con­se­quences for global agri­cul­ture and its reg­u­la­tion.

Glyphosate is one of the world’s most widely used weed­killers. Used for more than 40 years, it is in hun­dreds of plant-pro­tec­tion prod­ucts. You’d find it in most gar­den sheds across Aus­tralia un­der the brand name Roundup.

Com­mer­cial agri­cul­ture ac­counts for the bulk of global de­mand and the broad spec­trum weed­killer makes up a quar­ter of global her­bi­cide sales. The chem­i­cal is mainly used to com­bat weeds but also helps crops dry and ripen.

The use of glyphosate has long been chal­lenged by en­vi­ron­men­tal and health ac­tivists. Much of the op­po­si­tion has been based on a large dossier claiming to find ev­i­dence that glyphosate is “prob­a­bly car­cino­genic”. This was pub­lished in 2015 by the In­ter­na­tional Agency for Re­search on Can­cer (IARC), part of the World Health Or­gan­i­sa­tion. What could be more sci­en­tif­i­cally re­spectable, you may ask.

Well, when it was sub­ject to more de­tailed anal­y­sis, ex­perts found the IARC re­port re­lies on a tiny num­ber of stud­ies, and even these don’t sup­port its con­clu­sion. The ev­i­dence it causes can­cer in hu­mans is es­pe­cially ten­u­ous, based on three epi­demi­o­log­i­cal stud­ies with con­found­ing fac­tors and small sam­ple sizes link­ing it to Non-Hodgkin lym­phoma (NHL).

The re­port was also shown to ig­nore stud­ies that don’t sup­port its claims. Fore­most is the US Agri­cul­tural Health Study, which has been track­ing 89,000 farm­ers and their spouses for 23 years. That study found “no as­so­ci­a­tion be­tween glyphosate ex­po­sure and all can­cer in­ci­dence or most of the spe­cific can­cer sub­types we eval­u­ated, in­clud­ing NHL.”

Last year, the Euro­pean Food Safety Author­ity com­pleted a re­assess­ment of

glyphosate as part of the EU’s pes­ti­cide re­newal process, which in­cluded a con­sid­er­a­tion of the IARC as­sess­ment. Us­ing a riskbased, weight-of-ev­i­dence as­sess­ment ap­proach, Euro­pean Food Safety Author­ity con­sid­ered an ex­ten­sive body of sci­en­tific ev­i­dence, in­clud­ing stud­ies not as­sessed by the IARC, and de­ter­mined there was no cred­i­ble ev­i­dence that glyphosate causes can­cer in hu­mans.

Aus­tralia’s agvet chem­i­cal reg­u­la­tor, the Aus­tralian Pes­ti­cides and Vet­eri­nary Medicines Author­ity (APVMA) con­trols the use of all chem­i­cals in Aus­tralia, in­clud­ing glyphosate. It is re­quired un­der leg­is­la­tion to en­sure that any pes­ti­cides reg­is­tered for use in Aus­tralia have been through a ro­bust chem­i­cal risk as­sess­ment process and are safe to use, pro­vided they are used as per the la­bel in­struc­tions.

In 2016, the APVMA also con­ducted an eval­u­a­tion that in­cluded a com­mis­sioned re­view of the IARC mono­graph by the fed­eral De­part­ment of Health, and risk as­sess­ments by ex­pert in­ter­na­tional bod­ies and reg­u­la­tory agen­cies.

The re­view com­mis­sioned by the De­part­ment of Health was in two phases. The first iden­ti­fied which stud­ies re­lied on by IARC should be re­viewed in more de­tail, while the sec­ond in­volved a de­tailed as­sess­ment of those stud­ies.

APVMA con­cluded glyphosate does not pose a car­cino­genic risk to hu­mans and there are no grounds to place it un­der for­mal re­con­sid­er­a­tion.

Al­though the as­sess­ment of glyphosate by EFSA sim­i­larly con­cluded that glyphosate is not likely to be car­cino­genic in hu­mans, a num­ber of mem­bers of the Euro­pean Par­lia­ment were con­cerned that the as­sess­ment by IARC dif­fered to that con­ducted by in­ter­na­tional reg­u­la­tors, in­clud­ing the Euro­pean Food Safety Author­ity.

Last year, the Euro­pean Com­mis­sion tem­po­rar­ily ex­tended the li­cence for glyphosate use for 18 months, pend­ing more sci­en­tific anal­y­sis and fol­low­ing a split by mem­ber na­tions over a pro­posed nine-year ex­ten­sion. That fol­lowed a six-month ex­ten­sion that pre­vented the li­cence from ex­pir­ing as orig­i­nally sched­uled in De­cem­ber 2015. The cur­rent li­cence ex­pires next month.

Even if the li­cence is al­lowed to ex­pire, mem­ber states may be able to re­quest some ex­emp­tions from a ban, and the com­mis­sion could pro­pose a shorter re­newal pe­riod with us­age re­stric­tions.

Any EU de­ci­sion to fur­ther reg­u­late or ban glyphosate will have con­se­quences for Aus­tralian agri­cul­ture, so the process is be­ing closely watched here.

Sadly, we live in an age where ra­tio­nal sci­ence-based ev­i­dence strug­gles to stand against ill-in­formed opin­ion.

Mod­ern me­dia builds walls around com­mu­ni­ties of shared views that con­firm peo­ple’s think­ing; and at­tack, ban or sys­tem­at­i­cally re­pu­di­ate peo­ple with dif­fer­ing ideas. Sur­rounded in our echocham­bers, self-ap­pointed ex­perts dis­con­nect us from ev­i­dence-based di­a­logue, raise emo­tional ar­gu­ments to the point where anec­dote serves as ev­i­dence and build trust by el­e­vat­ing fears and vul­ner­a­bil­i­ties.

Let’s hope that this time com­mon sense wins out.

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