Methamidophos sprøytemiddel

Innledende betraktninger rundt sprøytemiddelet Methamidophos (Monitor), et nervetoksisk organofosfat.

Pollen på en tønne med vann.

En venn på facebook postet link til en video av aktivisten Michael Pollan, You’ll Never Eat McDonald’s French Fries Again After Watching This. Han snakker om hvordan McDonalds bare bruker Russet Burbank poteter uten flekker (net necrosis). For å unngå flekker må man unngå en type bladlus (aphid), og da må man sprøyte med insektmiddelet Methamidophos (også kjent som Monitor). Foredraget er fra 2013, i regi av RSA (Royal Society for the encouragement of Arts, Manufactures and Commerce). Videre sier han at Methamidophos er så giftig at etter at bøndene i Idaho har sprøytet vil de ikke bevege seg ute på åkeren på 5 dager. Og etter innhøsting må potetene oppbevares på lagre så store som fotballbaner i 6 uker for å avgasse sprøytemidlene, slik at de skal bli spiselige.

Jeg spiser så godt som 100% organisk selv, og aller helst biodynamisk, og er veldig imot sprøytemidler. Jeg er interessert i spørsmål rundt sprøytemidler. Jeg er også opptatt av at informasjon er riktig. Så jeg besluttet å sjekke litt rundt dette med Methamidophos.

Jeg leste ført wikipedia siden om Methamidophos. I en av referansene, et EPA dokument, Federal Register Vol. 74, No. 183 Wednesday, September 23, 2009 Notices, side 48551-48554, står det at Methamidophos ble faset ut i 2009. Produsentene hadde frivillig trukket tilbake sin lisens til å selge produktet. Jeg sendte to email. En til Michel Pollan for å få hans svar på dette. Og en til EPA for å høre om de kunne bekrefte dette og svare på ytterligere spørsmål.

Michael Pollan svarte dessverre aldri på min henvendelse.

Emailen til EPA: My question – is Monitor and other Methamidophos based insecticides legal to use in the USA? Or are they banned? I am interested in information about all uses, and primarily for potato crops.

Svar fra EPA: Products containing methamidophos can no longer be legally used in the US. All methamidophos products were cancelled as of December 31, 2009. All of the methamidophos tolerances expired as of December 31, 2013.

Ny email til EPA: Hi, thank you for your kind and very interesting answer. Just a few follow-ups, just to be sure: 1) When a product gets canceled – does this mean that it is no longer legal to sell? Or to use? Is it legal to use up already bought methamidophos after Dec 31-2009? 2) I understand that tolerances refer to residue pesticide on produce. What does it mean when the tolerances expire? Does this mean that it is no longer legal to sell produce with any methamidophos residues? (that the tolerance, in effect, is 0) Could a grocery store be breaking the law by doing so? Even if the pesticide does not come from spraying, but rather by residues already in the soil from earlier spraying (when it was still legal)?

Svar fra EPA:

To answer the questions in your last email. When a product is cancelled, in many circumstances it may still be sold and used. The Federal Register [Notat: referansen på Wikipedia siden var Federal Register] notice that cancels a product will contain a section with provisions for the disposition of existing stocks of the remaining products. The cancellation order for the last products containing methamidophos (Monitor) published in the Federal Register on September 23, 2009 (74 FR 48851). For methamidophos, the products were cancelled with an effective date of December 31, 2009. The registrants (Bayer) were permitted to sell and distribute existing stocks until December 31, 2010. Persons other than registrants (retailers and end users) were permitted to sell and use the product until their supply was exhausted.

Someone who has a product containing methamidophos could still use the product today. However, they must follow the label directions. Sue [Notat: hun som svarte på første emailen jeg sendte, se ovenfor] indicated in her 9/12/19 email, “products containing methamidophos can no longer be legally used in the US.” They actually could be used today, if someone had any left. However, since the only labeled uses remaining when methamidophos was cancelled were potatoes, cotton, and tomatoes, and the tolerances for those commodities have been revoked, the grower should have used any existing material before the tolerances were revoked.

To answer your second question, you are correct that tolerances refer to residues on produce. The process to revoke a tolerance starts with the cancellation of the products. The methamidophos products were cancelled in 2009. However, the existing stocks provisions could allow use after that. The EPA waits a few years after the product cancellations before starting the tolerance revocation process. That allows commodities that have been treated with methamidophos to clear through the channels of trade before the tolerances are revoked. (For example, methamidophos could previously be used on tomatoes. Since tomatoes could be processed and canned, the shelve life for those goods could be a few years.) EPA also will publish a proposed tolerance revocation action with a public comment period before the final action to revoke the tolerances.

The methamidaphos tolerances were revoked in December 2013. Yes, this means that the tolerance is in effect 0 and no residues of methamidophos should be on produce. If produce containing methamidophos residues is sent to the US, the shipment will be detained or destroyed if methamidophos residues are detected upon inspection. I do not know who (e.g., store, grower, shipper) is responsible if the residues are detected after entering the US. As for residues in soil from earlier spraying, it would be good to have an understanding of the environment fate characteristics (like degradation and persistence) of methamidophos to answer that question.

Dette er dermed et eksempel på at alt på facebook og youtube ikke behøver være nøyaktig.

Methamidophos fungerer som en cholinesterase (samme som acetylcholinesterase) inhibitor, også i mennesker. Acetylcholinesterase er et enzym (det vil si en katalysator, et stoff som inngår i og gjerne øker hastigheten på kjemiske reaksjoner uten selv å bli brukt opp) som er viktig for at nervesystemet skal fungere – for at nerveimpulser skal sendes på riktig måte. Methamidophos reduserer aktiviteten av dette enzymet. Methamidophos er derfor en nervegift.

Videre er methamidophos en organophosphate insecticide/acaricide (flått, lus)/avicide (fugler). Organofosfat: O=P(OR3). Organofosfater er estere av fosfor syre. Fosforsyre er en svak syre med formel H3PO4. En ester er en syre der en OH gruppe er erstattet med en -O-alkyl gruppe. Et alkan er et hydrokarbon der alle C-C bindingene er enkle. Eksempelvis metan, CH4, og etan, CH3CH3. Et alken har en C=C dobbeltbinding, for eksempel ethene (også kalt ethylene), C2H4. C2H2 er ethyne (også kalt acethylene) og har en trippelbinding mellom karbonatomene og er det enkleste alkynet. En alkyl gruppe er en enhet -CH2-CH3, altså bygget fra et alkan. Det er et alkan som mangler en H.

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