7 Antworten zu „What are Maximum Residue Levels (MRLs) for pesticides? A short explanation.“

1. 

   George Nikolich

   November 27, 2017

   You ignore your own references and continue to claim MRLs are primarily a toxicology-driven standard rather than a regulatory one. It is not that toxicology is not considered in establishing MRLs, is that the primary function of MRLs is to regulate the use of pesticides in a way that ensures “reasonable certainty of no harm.” An MRL exceedance does not make “reasonable certainty of harm” inevitable. While there have been exceedances reported by FDA in their Pesticide Residue Monitoring Program, in the past five years, there has not been a single recall issued by the FDA based on an exceedance which was more than just of regulatory concern.

   As you document, an MRL is established by determining the amount of residue that remains on food after application using good agricultural practices of the highest legal rate. That residue is then considered in the context of “…dietary risk assessments to ensure all tolerances established for each pesticide are safe.” That is not the same thing as claiming all MRL exceedances are unsafe. It is entirely possible that the amount of residue identified through that process is orders of magnitude less than what can be said to ensure a reasonable certainty of no harm given those dietary risk assessments.

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2. 

   Thomas

   November 27, 2017

   I did not claim anywhere in this post that „MRLs are primarily a toxicology-driven standard“. As I make abundantly clear, MRL setting uses two lines of evidence: GAP & toxicological assessments. Actually, three lines of evidence, if one counts those MRLs that are set using analytical limits of detection (in the EU system).

   Consequently, the role/impact of the toxicological assessment is different, depending on whether the MRL was set driven by GAP, toxicology or analytical chemistry.

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3. 

   George Nikolich

   Dezember 1, 2017

   While the establishment of MRLs includes consideration of ingredient toxicology, it should be noted that MRL is a legal limit and not a toxicological reference. For instance, a pesticide residue measured on food in the EU is not considered „unsafe“ based on MRL, it is only after an individual risk assessment is performed that such a determination is made. That process is described in section 5 starting on page 79 of the 2015 EU pesticide residue report. https://www.efsa.europa.eu/en/efsajournal/pub/4791

   In the EU, when a pesticide residue is found to represent a serious direct or indirect risk to human health, it is reported to the Rapid Alert System for Food and Feed (RASFF). The most recent pesticide residue data available represents 84,341 total samples, 2,366 MRL exceedances, and 204 RASFF notifications (approx 0.3%). http://onlinelibrary.wiley.com/doi/10.2903/j.efsa.2017.4791/full

   It should also be noted that the EU pesticide residue monitoring program is „targeted“ and, based on residue history and regulatory updates, pays particular attention to those foods likely to be of concern. Therefore, reported exceedances would tend to overestimate exceedances for all foods consumed and EFSA explicitly states with respect to reported residues: „However, it should be stressed again that since the national control programmes are targeted sampling strategies, the identified cases of MRL exceedances should not be considered as being statistically representative of the food available to European consumers.“

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   1. 

      Thomas

      Dezember 2, 2017

      What is the term „toxicological reference“ supposed to mean? Obviously, a value that is used in a regulatory context, such as a MRL, is a legal limit. However, that doesn’t mean that it cannot also be driven by the toxicological assessment of the compound. It’s not either a legal limit or a toxicologial reference (whatever that exactly means). It’s both. As explained in the detail in the post above.

      The rest of you comment states some arbitrary facts from the report that you found on EFSA’s homepage, which don’t add to the discussion. Yes, EFSA has published a report on the results of the EU pesticide monitoring (they actually do that annually). Yes, 84341 samples were taken. Yes, 2366 MRL exceedances were found. Yes, 204 RASFF notifications were filed. So what?

      But you have one point. The national monitoring programs are indeed targeted. However, that obviously holds true also for the amounts of pesticides found in organic food. My comparison between conventionally and organically produced food therefore still holds.

      If you would read instead of cherry-pick, you would have come across the following sentence in the EFSA report, just above your quote: „In these analyses, EFSA put specific emphasis on MRL exceedances as these findings may give indications of agricultural practices not in line with the legal provisions or potential consumer risk.“ Which, again, supports the arguments laid out in my post.

      I have repeatedly asked you:
      We agree that a food item in which a pesticide is found at a concentration below the MRL is considered safe according to our current understanding of the pesticide active ingredient in question, and under the assumption that this pesticide would be the only chemical a consumer is exposed to, via food, water, air and other consumer products (e.g. plasticis, cosmetics and personal care products). How do you then call a food item in which the pesticide concentration exceeds the MRL? And how do you think a regulatory authority should react on such a finding?

      I am going to end a discussion that is turning largely pointless, as you constantly dodge questions that you find uncomfortably challenging. Your preconceived notion that MRLs can simply be ignored, because they are supposedly not rooted in a toxicological assessment simply doesn’t fly. See for example the simple summary from the EU’s Directorate General for Health and Consumers (now: Directorate for Health and Consumers) (I’ve pointed you that that flyer before).

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      1. 

         George Nikolich

         Dezember 2, 2017

         You said: „How do you then call a food item in which the pesticide concentration exceeds the MRL? And how do you think a regulatory authority should react on such a finding?“

         You simply call it a food item with an MRL exceedance and perform an individual risk assessment, which is exactly what the regulatory authorities do in the EU. MRL exceedances are then judged against reference values. ARfD and ADI are reference values, MRLs are not.

         You said: „If you would read instead of cherry-pick, you would have come across the following sentence in the EFSA report, just above your quote: ‚In these analyses, EFSA put specific emphasis on MRL exceedances as these findings may give indications of agricultural practices not in line with the legal provisions or potential consumer risk.‘ Which, again, supports the arguments laid out in my post.“

         POTENTIAL consumer risk. Yes, exactly, „potential“ risk is not „actual“ risk without further analysis. „Potential risk“ does not equal „unsafe“ within current EU regulatory language. There were 2,366 cases of potential risk (MRL exceedances) and 204 cases of actual risk (RASFF notifications) in 2015. Using your logic, one could say there were 84,341 cases of potential risk prior to residue analysis, therefore, all food is unsafe. That EFSA quote does not support your argument.

         I never said that MRLs can be ignored or that toxicological considerations are not a component of MRLs. What I did say is that one cannot conclude that a pesticide residue renders a food item unsafe based on MRL alone, that a food item is only considered unsafe after the described individual risk assessment. That’s the „so what“ with regard to 204 RASFF notifications.

         My specific objection from the start has been that your claim, „…3% means that you eat roughly 30 food items per year that contain unsafe levels of a pesticide.“ is inaccurate and greatly exaggerated to the point of fear mongering about the safety of food in the EU.

         You have finally admitted that your 3%, 30 food items claim is not supported by the evidence, but say that doesn’t change the fact that there are more unsafe residues on conventional food than on organic. In presenting those incorrect 3%-30 statistics, you made a claim about the overall safety of the food supply, not just the relative difference between conventional and organic. Misrepresenting those statistics by an order of magnitude or more is not a trivial error.

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         1. 

            Thomas

            Dezember 2, 2017

            Your argumentation with RASFF notifications doesn’t work here. RASFF is only concerned with acute risks, not with chronic risks. MRLs, however are supposed to ensure that even long-term consumption of a food item does not lead to an exceedance of the ADI. Which is why RASFF notifications are driven by the term „serious risk“ (i.e. risk of acute health effects, even after short-term exposure).

            What I did say is that one cannot conclude that a pesticide residue renders a food item unsafe based on MRL alone, that a food item is only considered unsafe after the described individual risk assessment.

            Of course can one conclude that, and on very good grounds. It all hinges on the definition of „risk“ and „safe“. The fact is, an MRL exceedance implies that the concerned food item is not qualified as safe for human consumption without further study. I call that „unsafe“ – you might call it „a food item with MRL exceedance“. I call driving a car with 100 km/h through a residential area „unsafe“ – you might call it „a car with speed limit exceedance“.

            In the case of MRLs, further evaluation (which I guess is what you call „risk assessment“) might then end up with the conclusion that the MRL exceedance for this particular food item might in fact be quite acceptable, or it might conclude that the consumption would lead to an exceedance of the ARfD (and consequently a RASFF notification) – and anything in between.

            You have finally admitted that your 3%, 30 food items claim is not supported by the evidence, but say that doesn’t change the fact that there are more unsafe residues on conventional food than on organic.

            Let’s be clear here. What I wrote is:

            That is, 3% of food items from conventional production that were sampled across Europe contained pesticide residues above the safe level . It’s up to you to decide whether that is a lot or only a small fraction. Assuming three meals per day, 3% means that you eat roughly 30 food items per year that contain unsafe levels of a pesticide. Eating organic foods means that this happens only 7 times a year.

            So, I certainly stand by the first sentence. But you are correct, the third sentence implies that the monitoring of food items reflects the average consumption, while, as you pointed out, monitoring is biased towards food commodities that are know to be potentially problematic. The number of food items of an average consumer that exceed their respective MRL is therefore lower (by an unknown margin). I don’t get how you end up with „an order of magnitude“.

            And, although of course details are relevant: let’s not forget that the post’s main line of argumentation was that one cannot compare conventional and organic agriculture without considering pesticide use. This whole debate is a minute side-show. The fact remains that organic food contains a lower percentage of MRL exceedances.

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            1. 

               George Nikolich

               Dezember 10, 2017

               RASFF does consider ADI in that if the results from an individual risk assessment for MRL exceedances indicates the food is likely to “pose a consumer health risk” based on ADI, it would be reported as such. In the most recent report, the only residues that meet those criteria were five samples with dichlorvos where “the mean estimated long-term exposure reached 143% of the ADI in the upper-bound scenario.” (Page 91.) However: “Considering that the active substance is no longer approved in the EU and that residues in imported products were found only sporadically (0.02% of the 66,640 overall samples analysed), according to the current scientific knowledge, dichlorvos was not likely to pose a consumer health risk.” (Page 92.)

               Having said that, the focus does tend to be on ARfD because it is assumed that exceedances are usually one-off events, something to do with a particular batch rather than something inherent in the food or its production that would lead to chronic exposure. However, as noted above, that does not mean that RASFF “is only concerned with acute risks.”

               Again, MRLs are not “supposed to ensure that even long-term consumption of a food item does not lead to an exceedance of the ADI,” they are a legal limit to regulate the use of pesticides and ensure the pesticide is used properly and within the bounds of its label. Only after a risk assessment is completed and a residue is considered within the context of ARfD and ADI, is a particular residue considered to pose a risk to consumer health or not. That can seem like a subtle distinction, and it is one that is often misunderstood, but nevertheless, that is the case.

               Regulatory authorities either conclude an exceedance is likely to pose a consumer health risk or it does not, and that determination is only made after the authority performs an individual risk assessment on a case-by-case basis. There is no regulatory language that justifies calling a residue, even an MRL exceedance “unsafe” before a risk assessment is completed. If you do that, you are making up your own set of standards and terminology. As the latest report indicates, only about 10% of MRL exceedances were determined to pose a consumer health risk.

               I never challenged your claim of a difference between conventional and organic, I only challenged your inaccurate and exaggerated claim about those in the EU consuming an average of 30 food items each year with residues above the safe level and your claim that MRL exceedance represents a toxicological data point that defines food as being unsafe. Considering the conservative assumptions that overestimate exposure in residue reports, and considering the way in which sampling is targeted, EU food is likely to be far more safe than you suggest.

               What can be said is that MRL exceedances increase the probability of a residue posing a consumer health risk, but that is not the same thing as saying every food item with an MRL exceedance is unsafe.

               As for your main line of argumentation: What if the incidence of unsafe residue on conventional was less than 1 and on organic, it was some fraction of that? Yes, there is still a difference, but I think it would result in a very different public perception compared to 30 versus 7.

               Considering how the public is constantly bombarded with misinformation and unsupported claims about pesticides, your 3%-30 claim can truly be perceived as fear mongering, intentional or not. For a scientist such as yourself, I would think getting the details right would represent more than a minute side-show.