The Herbicide Safety Question in Davis

By Roberta Milstein

Interested in the use of pesticides and herbicides by the City of Davis?  This Thursday, April 6th (7–9pm, Davis Senior Center), there will be a Community Workshop on Pest Management. This is a chance to let the City know what you would like to have happen with pesticide and herbicide use in parks, greenbelts, dog parks, open spaces, and other public areas, so all are encouraged to attend.

A recent Vanguard article by Anya McCann (“Barefoot in Central Park”) describes the fundamental issue.  Even if it were true that the pesticides in use by the City have been deemed by some to be safe, does it make sense to take a chance?  If we don’t use pesticides, the worst that can happen is that we need to use other, more labor-intensive methods and perhaps have a few more “weeds.”  (If you attend the Workshop, you will learn more about these alternative methods). It seems to me that this is a tradeoff well worth making.

(Why is “weeds” in quotes, you may ask?  It’s in quotes because “weed” is not a scientific term; it has no botanical significance.  A “weed” is just a plant that someone doesn’t want in a certain location.  One person’s “weed” can be another person’s wildflower).

But in a comment on McCann’s article, Don Shor stated that although he agreed that we can tolerate a few “weeds” in our parks and that it would be good to engage community members in helping with the upkeep, the decision to change to “greater use of organic herbicides…would be essentially a philosophical decision and should not be couched in terms of public safety.”  He further asserted: “Several important international regulatory bodies have studied glyphosate, and all concluded the herbicide is not a carcinogen,” listing off several of those agencies.

However, the scientific findings are less clearcut than Shor makes them out to be.

First, Shor left out one major international agency, the International Agency for Research on Cancer (IARC), which is a branch of the World Health Organization. IARC convened a meeting of 17 scientific experts from 11 countries and in March 2015 finalized its assessment, concluding that glyphosate is “probably carcinogenic to humans.”

Second, an internal memo that has come to light as a result of a lawsuit against Monsanto reveals that the Environmental Protection Agency (EPA) – one of the agencies that Shor listed in his comment – was in fact divided on the question of whether glyphosate (commonly sold as Roundup) is carcinogenic.

The split occurred between two offices within the EPA.  The EPA has an Office of Pesticide Programs (OPP).  It also has a science program, the Office of Research and Development (ORD).  In the internal memo, the ORD stated that it agreed with the IARC’s findings, which it understood to be that there is “limited evidence” of the carcinogenicity of glyphosate in humans. “Limited evidence,” the memo stated, means that “a positive association has been observed for which a causal association is credible, but chance, bias, or confounding could not be ruled out with reasonable confidence.”  But the OPP had said that there was no evidence that glyphosate is carcinogenic.  “Limited evidence” is different from “no evidence.” What’s going on?

It turns out that the OPP and the ORD took different approaches to their scientific analyses.  The EPA’s own Cancer Guidelines specify that risk assessment should consider “gradations of causality.”  That’s the standard that the ORD used.  But the OPP, in violation of the Guidelines, took a “yes/no” approach, so that the only two choices were “carcinogenic to humans” or “not likely to be carcinogenic to humans.” This rules out intermediate findings purely by definition.

(For further information on these and other differences between the ORD’s approach and the OPP’s approach, see and

And the fact of the matter is that there are many shades of grey when it comes to findings about carcinogenicity.  The OPP’s approach is highly misleading, and the ORD said as much in the internal memo.  Although the ORD did not decide which descriptor might be most appropriate for glyphosate, the memo states that one could argue that glyphosate is “likely to be carcinogenic,” that there is “suggestive evidence” for its carcinogenicity, or that there is “inadequate information to assess carcinogenic potential.”

I think it’s also worth noting that litigants claim that Monsanto has ghostwritten research that was later attributed to academics, an accusation which, if true, casts further doubt on those studies’ claims that glyphosate is not carcinogenic.

So, we are taken back to McCann’s original point.  There’s some reason to think that glyphosate might be harmful to humans.  Further study is needed, but in the meantime, we have less risky alternatives, where the worst that can happen is a few unplanned plants in the “wrong” places.  Surely that’s a tradeoff worth making in the name of precaution.  If you agree, please come to the Workshop on Thursday and let the City know your views.

About The Author

Disclaimer: the views expressed by guest writers are strictly those of the author and may not reflect the views of the Vanguard, its editor, or its editorial board.

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  1. Tia Will

    I have come out in the past with regard to air quality issues at the Nishi site as demanding causative and epidemiologic as opposed to merely speculative or correlative evidence on which to make major decisions. However, in this case, there are three reasons for my objection to the use of Roundup in our parks as  Roberta has alluded to despite the ambiguities of the research.

    1. The consequences of not using it are aesthetic. There is no major economic gain or loss if we do not use it. There are other means of “weed” abatement available even if less convenient.

    2. I agree that there is ambiguity about the potential risk as a human carcinogen from the available evidence. However, in this case, the minimal gain from usage is far outweighed by the possible harm of even minimal carcinogenic effects.

    3. Since it is our children who have the largest exposure over potentially the longest amount of time that are at risk from use in parks, I would suggest that the precautionary principle should certainly apply in this case.

    1. Don Shor

      I would suggest that the precautionary principle should certainly apply in this case.

      The precautionary principle guides the decision-making process of the European Food Safety Authority (EFSA) and was a factor in their deliberations. Glyphosate was not considered a carcinogen, but concerns about co-formulants that are added to some RoundUp brand products arose. That was the basis for the review by the European Chemical Agency (ECHA) cited in my first comment above, just released in March of this year.

  2. Don Shor

    Of the several agencies that have reviewed glyphosate, the IARC study is the most poorly considered and has been subjected to the greatest criticism by outside analysts.

    Several other regulatory bodies have studied glyphosate, and all concluded the herbicide is not a carcinogen, including:

    – Canadian Pest Management Regulatory Agency, (April 13, 2015)
    – EPA’s Cancer Assessment Review Committee (October 1, 2015)
    – European Food Safety Authority (November 12, 2015)
    – United Nations/World Health Organization (May 9-13, 2016)
    – German Federal Institute for Occupational Safety and Health to the European Chemicals Agency, (May 2016)
    – New Zealand Environmental Protection Authority, (August 2016)

    – European Chemical Agency (ECHA), (March 2017)

    Here is the actual text of the EPA’s conclusion:

    For cancer descriptors, the available data and weight-of-evidence clearly do not support the descriptors “carcinogenic to humans”, “likely to be carcinogenic to humans”, or “inadequate information to assess carcinogenic potential”. For the “suggestive evidence of carcinogenic potential” descriptor, considerations could be looked at in isolation; however, following a thorough integrative weight-of-evidence evaluation of the available data, the database would not support this cancer descriptor. The strongest support is for “not likely to be carcinogenic to humans” at doses relevant to human health risk assessment.

    Emphasis added.

    The city’s use of herbicides does not pose a risk to the public. Assertions about glyphosate or RoundUp being carcinogenic or endocrine disruptors are not supported by the evidence as reviewed by multiple international agencies tasked with assessing products for human safety.

    I have uploaded the EPA report of Dec 2016 here:

    The Executive Summary of the EPA report directly addresses the IARC report. See pages 7 – 10. The classification conclusions are on pages 77 – 78.

    1. Keith O

      I’m with Don Shor.  He has presented more facts and studies showing there’s no risk.  Why should we ban something on cherrypicked info?  Keeping our parks and greenbelts nice is important to me and I’m sure most Davisites.  Pulling weeds is very labor intensive, do we have the city funds and personnel to do this?  Thinking that volunteer groups will stay on top of pulling weeds in our public areas I think is very over optimistic at best.

      1. Anya McCann

        Do you think that Central Park looks weedy and messy? It is managed with the practices that I agree with. What about all of the PHAER zones?  I have not heard about anyone complaining about those.

        We have yet to see a labor and cost report from City staff yet to show us just how much time and funding they spend on spraying. And how much spraying is being done when staff have time on their hands to make busy work? I could include all kinds of studies here and we could keep a tally of those that are for and against. There are many pages of them in the sub-committee draft recommendations. But I choose to make a different argument since I don’t really think either side will be able to prove anything for 30 years when we are reviewing cancer and disease rates.  I question the motives behind all of the reports I’ve seen and am pretty pessimistic.

        However, if staff say they think that labor/costs will all wash out over a few years of preparatory practices, having done this work for myself and seen the great benefit I had with almost no weeds in the 3rd year, it passes the common sense test for me. If we can do it, why not?


      2. Howard P

        C’mon Keith, there is always risk… but I’m comfortable with the risk that I’ll be killed/maimed by a meteorite that strikes me in the coming year… or the coming decade… or within my lifetime… (pun unintended)

        Kinda’ how I feel about recommended use of glyphosate around my home or any public spaces I and mine frequent.  As Don has said previously, the total use of the active ingredient “of concern” is miniscule in all of Davis, as used by the City…

        1. Roberta Millstein

          How can you say that the ORD’s memo is just “part of the process”?  The report from the OPP within the EPA that you linked to is dated October 1, 2015.  The report that I linked to from the ORD within the EPA, criticizing the OPP’s report, is dated December 15, 2015.  In other words, the ORD – the part of the EPA that is responsible for research and development, found fault with the OPP’s final report.  And yet this information did not see the light of day until a lawsuit was brought against Monsanto.  (The lawsuit accuses Monsanto of knowing that glyphosate was carcinogenic, of ghostwriting academic articles about glyphosate, and of interfering with the EPA’s process).

          There was dissension within the EPA, yet it went unreported, possibly because of Monsanto’s interference.  That should make anyone who cares about the scientific process stand up and take notice.

          For those of you playing along, I recommend taking a look at the ORD internal memo.  It outlines a number of problems with what the OPP did other than what I described in my post.  Again, the link is here:

          1. Don Shor

            Much of what you are describing has also played out in the European regulatory agencies. Basically it all comes back to the IARP report and how it should be used, if at all.

            The Office of Research and Development in the EPA felt that the Office of Pesticide Programs should consider the IARP conclusion that there is limited evidence of a correlation (not causation) of glyphosate with certain cancers.

            The IARC uses a process of narrowing the number of studies that it includes in the process of developing their monographs about different substances. Out of a total of 14 studies, the IARC felt that 3 showed evidence of a “weak/dubious – but still existent – correlation and classifies such evidence as limited.”

            By comparison the European Food Safety Authority looked at hundreds of tests, published and unpublished. Using a weight of evidence approach, they consider the very small number of studies showing a correlation – along with the very large number of studies showing no correlation – as providing very limited evidence and concluded that glyphosate is not carcinogenic. That’s the same conclusion the other agencies I listed have come to.

            Because of conflicts about the EFSA report and lack of unanimity among the voting members of the European Community, the subject was sent to the European Chemical Agency (ECHA committee for Risk Assessment, RAC) which reviews these disputes and essentially conducts another review. They came to the same conclusion in a March 15 press release this year:
            “RAC concluded that the available scientific evidence did not meet the criteria to classify glyphosate as a carcinogen, as a mutagen or as toxic for reproduction.”

            It seems that this is the same conflict of analysis that took place within the EPA. I’m not sure why anyone would expect unanimity in the process, nor is it necessarily likely that the internal deliberations of a regulatory body would all be the subject of public review.

            I understand that everyone loves to hate Monsanto, but I don’t think this information that came out during discovery (I assume) has any real relevance to the final conclusions in the report. If you disagree, I’d be curious what you believe to the the actual technical importance of the difference is.

        2. Ron

          Don:  “It was part of the process. That is normal.”

          At times, this is exactly what causes me concern within regulatory agencies.

          Wondering if alternative methods can be tested on a limited basis (rather than city-wide, at this point). Seems like there’s interest in doing so.

          1. Don Shor

            Wondering if alternative methods can be tested on a limited basis (rather than city-wide, at this point). Seems like there’s interest in doing so.

            I think there are neighborhood parks where people really don’t want any pesticides sprayed, and would likely be willing to sustain an effort to do the extra labor to do it by hand and with mulches. As I said in my original comment, this kind of community-building effort is great whenever it occurs. We have a great example in the Central Park Gardens.
            I’d think that volunteer efforts would be less sustained on greenbelt areas or in less populated parks, and those are where I’d be concerned about things like the star thistle and the foxtails. But the IPM coordinator could address these specifics.

        3. Roberta Millstein


          (Again, for those following along – both the OPP (Office of Pesticide Programs) and the ORD (Office of Research and Development) are part of the Environmental Protection Agency (EPA). The ORD reviewers included two epidemiologists, a pathologist, and several scientists with significant expertise in cancer risk assessment).


          Here is a summary of the ORD’s critique of the OPP:


          1. The ORD objected to the OPP’s dichotomy between “causal” and “not causal”.  (You seem to make the same dichotomy).  Rather, the ORD says that a positive association has been observed and that a causal association is credible, but chance, bias, or confounding could not be ruled out with reasonable confidence.  And as noted in my original post, the ORD thinks that it is more appropriate to use gradations of causality rather than a “yes/no” approach — and this is also the EPA’s own guideline.


          2. EPA’s cancer guidelines state that “Trend tests and pairwise comparison tests are the recommended tests for determining whether chance, rather than a treatment-related effect, is a plausible explanation for an apparent increase in tumor incidence. Significance in either kind of test is sufficient to reject the hypothesis that chance accounts for the result” (emphasis added).  Contrary to these guidelines, the OPP primarily used pairwise comparisons.  But the trend tests yielded several significant results, which the OPP seems to gloss over.


          3. The ORD criticizes the OPP for using a study-by-study approach for their analysis, rather than using a systematic, integrated analysis of the data.


          4. The ORD criticizes the OPP for not including a thorough evaluation of the mutagenic potential of glyphosate.  They state that “if there is evidence of mutagenic potential or if a mutagenic potential has not been adequately ruled out, then characterization of glyphosate as ‘not likely to be carcinogenic’ could be problematic for this reason alone, given the lack of a high-quality negative epidemiological study” (emphasis added).


          The ORD then made some recommendations that would “strengthen OPP’s human health assessment and address the differences in the potential cancer findings.”  To my knowledge, these recommendations were not followed.



          It seems to me that the ORD is making a pretty damning critique of the OPP – the OPP failed to follow guidelines and the ORD made legitimate criticisms of the ORD that cannot easily be brushed off, which is what you seem to be doing.


          1. Don Shor

            There are five levels of conclusion about a substance that these agencies use:
            “Carcinogenic to humans.” (“Clearly not applicable,” says the ORP in this memo. So I urge that nobody make the bald assertion that glyphosate or RoundUp cause cancer.)
            “Likely carcinogen.”
            “Suggestive evidence of carcinogenic potential.”
            “Inadequate information to assess carcinogenic potential.”
            “Not likely to be carcinogenic.”

            The EPA conclusion was #5: not likely to be carcinogenic.
            The OPP researchers argue that maybe it should be #4: inadequate information to assess carcinogenic potential. They say this because of a couple of tests that appeared to show positive trends. Other tests did not show positive trends. The other researchers at the EPA, who have equally impressive credentials, disagree with this analysis.

            Note that the ORP did not agree with the IARP conclusion of “likely carcinogen.” They simply found some ambiguity due to a couple of studies that may show a positive trend. Most other studies do not.

            There are hundreds of studies of glyphosate. The EFSA took this same issue, the same tests cited in this memo and many, many others, and concluded that there was adequate information. And reiterated their previous conclusion that it is not a human carcinogen.

          2. Don Shor

            It seems to me that the ORD is making a pretty damning critique of the OPP – the OPP failed to follow guidelines and the ORD made legitimate criticisms of the ORD that cannot easily be brushed off, which is what you seem to be doing.

            I would say that based on their critique it would be reasonable for the EPA committee to give a further explanation of why their conclusions differ from the IARP report and explain both their methodology and the specific test analyses in more detail. The conclusion is not of significance to the regulatory process of registering and setting allowable uses of glyphosate. Also, the additives in various glyphosate formulations should perhaps be reviewed separately.

            But none of this suggests or even comes close to proving that glyphosate is harmful or hazardous or carcinogenic, particularly at real-world rates of exposure. The use of glyphosate by the city park staff is not a risk to the public. Risk is not a reasonable basis for changing the city herbicide use policy. It is a philosophical preference for not using pesticides, which I am very familiar with and perfectly happy to support. Just please don’t try to tell the public that there is any risk from current practices.

        4. Roberta Millstein

          Don, I have been very careful in my language.  Nowhere did I make the “bald assertion that glyphosate or RoundUp cause cancer,” as you seem to imply that I did.  But you are misrepresenting what the ORD said in the memo. They did not conclude that there was inadequate information to decide the carcinogeniety of glyphosate, as you state.  Rather, as I stated in my original article above, the ORD memo states that one could argue that glyphosate is “likely to be carcinogenic,” that there is “suggestive evidence” for its carcinogenicity, or that there is “inadequate information to assess carcinogenic potential.”  They did not decide between these options in the memo.

          And, contrary to what you say, the ORD memo states explicltly that it does agree with the IARC’s findings.

          My point was, and continues to be, that given the possibility that glyphosate/Roundup could be harmful, and there is so little lost in failing to use glyphosate/Roundup, that we should stop using it.  It seems as though you reach the same conclusion (that we can stop using pesticides in the City’s public areas) through different means: fine.  But please don’t misrepresent the scientific conclusions made by the EPA’s ORD.

          1. Don Shor

            Nowhere did I make the “bald assertion that glyphosate or RoundUp cause cancer,” as you seem to imply that I did.

            Others, not you. Sorry I didn’t make that distinction.

  3. Tia Will


    Keeping our parks and greenbelts nice is important to me and I’m sure most Davisites”

    I agree with you that Don has certainly provided the most extensive evidence with regard to the risks of Roundup and I freely admit to an anti chemical bias if acceptable results can be obtained by other means. However, you applaud him for this and then in the same post make the most highly subjective comment that I have heard yet on this issue. I refer to your use of the word “nice”.

    “Nice” means dramatically things to different people. Just this last weekend my partner and I had a laugh about this subjectivity when walking past the student cooperative houses on the corner of 3rd and J. The yards of these houses are variably kept depending on the ambitions of the inhabitants. Some years the yards are well maintained with “weed” abatement and well tended gardens. This year virtually no maintenance at all has been done. My partner was bemoaning the prolific exuberance of untended nature. I, being a country girl at heart, was enjoying the same proliferation of plant life of many different types, most of which people would categorize as “weeds”. So whose version of “nice” should prevail ?

    1. Keith O

      I think most people would categorize “nice” as in well tended and mostly weed free.  Do you also think it “nice” when you see weeds growing in the cracks of sidewalks, in the crevices where the streets meet the sidewalks, etc.

      Another thing to consider is if we let weeds go unattended our dogs are going to be much more susceptible to foxtails and the weeds with the round bury balls (Don?).

      So whose version of “nice” should prevail ?

      I think the universal version of “nice” when it comes to gardens, parks and landscaped greenbelts would be more or less weed free.

      1. Howard P

        Indeed, there are “weeds” (technically, any plant not intended to be where it is, so, an apple tree in the midst of an almond grove is a ‘weed’), and “noxious weeds”, such as foxtails, Star Thistle, the ones that create burrs (burr clover?), ragweed, etc., that can present true hazards to folk including pets, bicyclists, people who breathe and are allergic.

        Non-chemical eradication/control is often more time consuming (hence more expensive) than using chemical methods.

        Balancing act…

      2. Roberta Millstein

        no one is proposing that the weeds go unattended. if you go to the workshop on thursday, you will learn about all the ways that the weeds can be controlled without using herbicides. on my phone, sorry for lack of punctuation

      3. Richard McCann

        Keith O

        Sorry, but “nice” is not universally defined, and you should not try to impose your definition. I personally prefer waterwise native plant gardens to thirsty Midwestern groomed lawns. Most of the people I know prefer the former over the latter, so is my anecdotal observation predominant over yours? Does your definition trump my definition? The aesthetic assessment is too difficult to parse, so we are left with the risk assessment.

        Given the growing evidence of corporate ghostwriting of research across a variety of venues, we have much more difficulty in discerning the truth in science. We should be cautious where we can’t tread with certainty.

        And it may be possible that hand-weeding is cost effective over the long haul. We don’t yet know all of the answers to these questions, so it is premature to come to a conclusion.

        1. Keith O

          And it may be possible that hand-weeding is cost effective over the long haul. We don’t yet know all of the answers to these questions, so it is premature to come to a conclusion.

          Well I know when I hand weed my gardens it’s always much more labor intensive than when I spray some Roundup.  I would have to believe that it would be the same for public areas except multiplied by thousands.

          Given the growing evidence of corporate ghostwriting of research 

          I don’t think that Don Shor cited “ghostwriters”.  That said, ghostwriting isn’t just owned by corporations, many times environmentalists and naturalists will employ the same tactics.



      4. Don Shor

        our dogs are going to be much more susceptible to foxtails and the weeds with the round bury balls (Don?).

        Yes, foxtail barley and bedstraw would require a level of vigilance by volunteer crews that I would be concerned about. Foxtails in particular can cause significant harm to the health of pets and considerable expense to their owners. They are very readily managed by early-season applications of glyphosate. They would require more frequent and supervised visits by work crews.
        I would also be concerned about star thistle and other thistles increasing in some park areas.
        Systemic herbicides are also used to manage hard-to-kill perennial weeds. Some, such as bermudagrass and nutsedge, will invade flower beds and choke out lower-growing plants. It is likely that the parks department would simply abandon those areas to them, mulch heavily, and leave it at that.
        I suggest staff be asked what their main weeds are that they are managing with glyphosate. The use report shows a relatively small amount of use city-wide, with much greater use of the organic alternative (Scythe) for top kill management of annual weeds. I discussed the tradeoff of Scythe vs. glyphosate in the original comment Roberta is addressing here.

        1. Keith O

          Foxtails in particular can cause significant harm to the health of pets and considerable expense to their owners.

          Yes, I’m sure my vet has taken a nice vacation on what I’ve paid her to extract and treat foxtails for my dog.

        2. Howard P

          Keith, do you not see that having a dog is a form of slavery, animal abuse, waste of resources (food/water), contributing to pollution/environmental degredation (at the ‘other end’ of the food/water thing), etc.?

          I intend to have a dog in my life until I no longer have life…

          Oh, and the danger to dogs, includes dangers to ‘service dogs’ (yeah, more intense ‘slavery’)… many people depend on service dogs… perhaps the right answer is to eliminate every human on earth. Then, most problems disappear…

  4. Tia Will

    Given that as the only two choices, I would agree. However, the first is way too structured and manicured for my taste and I am sure that there are an infinite number of choices somewhere in between the two.

    The only real substantive point made are about the foxtails and other potentially injurious plants. I agree those should be managed and would be interested in hearing how, besides Roundup, they might be managed appropriately.

    1. Keith O

      The only real substantive point made are about the foxtails and other potentially injurious plants. 

      That’s your opinion.  IMO there were many substansive points made.  Don Shor has linked several studies that show that glyphosate isn’t a carcinogen and we know that going away from herbicides is going to be very labor intensive and most likely cost much more in city personnel wages.  I feel that citing the confined space of the Central Park gardens in now way can be projected to cover the entire city’s infrastructure with its multitude of parks, public areas, gardens and miles and miles of greenbelts.

    2. Don Shor

      Conventional management without glyphosate would be application of a pre-emergent herbicide in fall before the rainy season.
      Organic herbicides: spray with top-kill products such as Scythe 3 – 4 times from mid-winter to early spring.The plant will repeatedly re-sprout (these materials are very similar to just mowing or cutting the plant) and will continue to try to flower and seed.
      Non-herbicide: by heavy mulching at first in late summer/early fall (3 – 4 inches of coarse mulch such as the ground wood products from tree pruning), then hand weeding 2 – 3 times from about February through April.
      In all cases: careful monitoring is needed along pathways, open areas in greenbelts, etc. Right now is when you want to get it out before the seed heads set.

        1. Roberta Millstein

          Why not go to the meeting on Thursday and ask these questions to Martin Guerena, the City’s IPM expert?  He can give you a more complete picture of what he would do, how much effort it could take, and what the cost would be.

  5. Howard P

    Just wondering… if “sunscreen” chemicals could not be proved to be 100% safe (zero risk of morbidity/mortality), should we ban its use?  We actually apply those to our bodies, particularly small children… hmmmm…

    1. Roberta Millstein

      That’s disanalogous, for two reasons:

      1. It’s a personal choice whether to use sunscreen or not, and it affects only the user of the sunscreen. The herbicide issue is a policy issue that affects all users of public spaces in Davis (including non-human species).

      2. The harm from not using sunscreen is potentially getting skin cancer, which, depending on one’s exposure and skin type, can be fairly high.  The harm from not using glyphosate is some extra effort and perhaps a few plant visitors in the first few years until the new methods take hold.  So, serious harm vs. little harm.

      When it comes to sunscreen, I think that consumers should be given all the available information and then make their own decision.  Since I am out in the sun a lot, and since I have a family history of skin cancer (and a personal history as well), I use sunscreen.  But I would not fault someone for making a different decision for themselves or their family.


        1. Roberta Millstein

          Ron, I don’t think all sunscreens use nanoparticles. It’s certainly worth considering the impact of sunscreens on the environment, and if those turned out to be considerable I would change my view.  But discussing sunscreen is for another time and place.  I think we should keep this to herbicide and pesticide use by the City of Davis.

    2. Don Shor

      Speaking of risk…
      From the Hazardous Materials subcommittee report on glyphosate:

      Green Herbicides: Successful use of the soap-based herbicide Scythe in the green zones and sensitive areas and the combination with Glyphosate has contributed to the reduction of our conventional pesticide use. The recommended rate for a Scythe Glyphosate mixture is 1 ounce of roundup per gallon mix with 2-3 ounces of Scythe. Glyphosate alone is mixed at 2.66 ounces to achieve a 2% solution. A new organically approved herbicide, Suppress, which has Caprylic and Capric Acids as active ingredients and will be evaluated for use in our green areas as well as with a Glyphosate mixture.”

      Most glyphosate materials have a Caution label, the lowest toxicity level for pesticide labeling.
      Both Scythe and Suppress have Warning labels, due to their greater risk of eye injury especially to the person applying them. They’re organic, but higher risk to the applicator than the conventional herbicide.
      In effect. we are being told that city staff should stop using glyphosate because the public perceives it as a risk, and should instead be applying organic materials that are more hazardous to the people doing the application. They want their lower perceived risk to be replaced by a higher actual risk to someone else.
      I think we often forget in these discussions about the risk to the applicators: the city staff doing the spraying.

      I expect I will be told that the goal is use of no herbicides. But that isn’t what’s in the Hazardous Materials subcommittee report. As cited above, the committee members are touting the use of these materials. I wonder if they actually read the labels and how many of them have a working understanding of the hierarchy of Signal Words and Precautionary Statements on pesticide labels.

      1. Keith O

        I’ve tried the soap based weed control products and found them to be useless.

        Maybe the city can hand out free little garden shovels and make every citizen responible to dig out ten weeds a day?

      2. Mark West

        “I wonder if they actually read the labels and how many of them have a working understanding of the hierarchy of Signal Words and Precautionary Statements on pesticide labels.”

        I suspect that for most, the level of ‘understanding’ is limited to: ‘Organic is good, non-organic is bad.’

        My problem is not with the safety of the products, but with the poor performance of the applicators, at least those working in the park over my back fence. My neighbors and I have lost countless plants over the years due to overspray from the improper application of the products along the fence line. If that is a common problem around the City then the specific products are not the issue.


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