March 18, 2019

Councilmember Tom Hucker Montgomery County Council 100 Maryland Ave, 6thFloor Rockville, MD 20850

Dear Councilmember Hucker,

I’m writing in response to your letter of November 21, 2018, in which you urge the Department of Parks to immediately discontinue the use of glyphosate-based herbicides in the parks — due to human health concerns and potential liability to Montgomery County (per a recent jury verdict in the state of California). I have carefully considered your request in consultation with my staff and a review of relevant literature on glyphosate.

The State of Science

Your health concerns apparently are aroused mostly by the World Health Organization’s International Agency for Research on Cancer (IARC) because it classified glyphosate in March 2015 as “probably carcinogenic to humans.But that classification is plainly at odds with more authoritative pronouncements issued by domestic researchers and a number of federal authorities.

Specifically, in December 2017, the United States Environmental Protection Agency announced the release of its draft human health and ecological risk assessments for glyphosate. As indicated in the announcement:

[G]lyphosate is not likely to be carcinogenic to humans. The Agency’s assessment found no other meaningful risks to human health when the product is used according to the pesticide label. The Agency’s scientific findings are consistent with the conclusions of science reviews by a number of other countries as well as the 2017 National Institute of Health Agricultural Health Survey.

Similarly, the May 2018 Journal of the National Cancer Institute reported about a particular study as follows:

In this large, prospective cohort study, no association was apparent between glyphosate and any solid tumors or lymphoid malignancies overall, including NHL [non-Hodgkin lymphoma] and its subtypes. There was some evidence of increased risk of AML [acute myeloid leukemia] among the highest exposed group that requiresconfirmation.


The U.S. Food and Drug Administration recently summarized the literature:

The EPA evaluates the safety of pesticides such as glyphosate. According to EPA, glyphosate has a low toxicity for people. Pets may be at risk of digestive or intestinal problems if they touch or eat plants that have just been sprayed. In December 2017, the EPA issued a Draft RiskAssessments for Glyphosate concluding that glyphosate is not likely to be carcinogenic in humans.

One international organization (the International Agency for Research on Cancer) concluded that glyphosate may be a carcinogen, while several others, including the European Food Safety Authority and the Joint Food and Agriculture Organization (FAO)/World Health Organization (WHO) Meeting on Pesticide Residues (JMPR), have determined that it is unlikely to be a carcinogen.

Considered in this context, while there may be somewhat divided science on the health risks of glyphosate, the 2015 assessment by the IARC may be an outlier since the majority of interested organizations simply do not concur.

Reductions in Use

Even though we may not be compelled by the state of the science, as a precautionary measure undertaken to moderate public fears, the Parks Department has, and will continue to reduce its reliance on pesticide application as part of its Integrated Pest Management program and will reduce its use of glyphosate-based products as a part of this effort.

Hopefully, over time, public concerns will dissipate as more people learn that glyphosate is an effective and very cost-efficient tool to control weed growth that is – in and of itself – very harmful and damaging to our parks. Our staff does notuse glyphosate-based herbicides for cosmetic purposes in the parks. To the contrary, the most common reasons that we apply the product are to:

  • control growth of non-native invasive plants in natural areas, which are highly damaging to the ecosystem;
  • protect the health of desirable plants and trees in landscape beds, mulch rings, and at our nurseries and plant propagationareas;
  • prevent degradation of infrastructure such as paved surfaces and
  • control rapid growth of weeds in baseball / softball infields and warning tracks, which can jeopardize the safety ofplayers;
  • remove weedy growth which obstructs visibility into park areas, which can compromise patron safety;
  • ensure safe operation of our miniature trains at Cabin John & Wheaton, by preventing growth of plants along the traintracks;
  • control weed growth in stormwater management structures which would compromise their intended function; and
  • control noxious weeds as required by Maryland Weed Control


The Parks Department Integrated Pest Management program has been successful in reducing the use of glyphosate-based products by incorporating several alternative methods for control. While generally successful, they are more costly and labor-intensive,including:


  • increased hand-weeding and stringtrimming;
  • propane flameweeding;
  • testing efficacy and safety of new products, including listed pesticides (a pesticide the active ingredients of which are recommended by the National Organic Standards Board) & organic products;
  • partnering with the University of Maryland in the testing of alternativeproducts;
  • use of sod-cutters to remove weeds and roots in mulch playgroundsurfacing;
  • creation of new equipment (a “weed-bar”) to remove weed growth in baseball/softballinfields;
  • increased use of tractor-mounted “bush hog” rotary mowers to cut weedyvegetation;
  • elimination of weed growth areas by design;and
  • continued growth of our “weed warrior” volunteer program to manually remove invasive

Regarding the safety of park patrons, our future glyphosate reduction efforts will target areas with the most public access. This will include athletic fields, picnic areas, community open spaces and other areas that receive high usage and visitation. Likewise, we will prioritize alternative weed-control methods in those areas.

Most recently, we learned about a relatively new technology that may present an herbicide-free solution for controlling unwanted vegetation. That technology combines heat with biodegradable foam to kill weeds. We plan to test this technology and continue looking for new alternatives to control weeds.

We submit semi-annual reports to the County Council that detail our pesticide reduction efforts including: maintenance of all 290 playgrounds without pesticides; maintenance of ten entire parks without the use of registered pesticides; continued testing of listed and organic products; and enhanced notification protocols and education programs about the application of pesticides. The report lists the location, product and purpose of pesticide applications in the parks over the six-month reporting period.

I will report on our project to conduct a pilot program consisting of at least five playing fields maintained without the use of registered pesticides in a separate memorandum.


Park Staff Safety


Regarding the safety of park staff and pesticide applicators, Montgomery Parks’ pesticide applicators are registered and certified through the Maryland Department of Agriculture (MDA). They are required to attend annual training courses as well as renew their certification each year. Training programs sponsored by the University of Maryland and other professional organizations are offered on a regular basis both internally and externally.

Our internal class content includes: pesticide laws and regulations; pesticide label comprehension; safety and emergency procedures; pest identification and control recommendations; pesticide application techniques; environmental and health concerns; and integrated pest management


principles. Our classes are designed to align topics and content with MDA pesticide applicator certification categories and are MDA approved to qualify our certified applicators for pesticide re- certification credits. As a result, we see high attendance, better test preparation for staff to pass the MDA certification exam, enhanced specialized skills for applying pesticides safely, and use of alternative practices for managing pest problems.

Park staff are expected to comply with all county, MDA, and Environmental Protection Agency notification, posting, label, and safety requirements when applying pesticides on parkland. Park staff who apply pesticides are directed to always wear required Personal Protective Equipment (PPE). The PPE is specified on the pesticide label for safe use during applications – to protect the human body from contact with pesticides or pesticide residues. PPE includes: protective suits, footwear, gloves, aprons, respirators, eyewear, and headgear.

I am committed to maintaining safe work environments for our applicators and all park staff.

Going Forward

Regarding your concern about potential liability, our attorneys have assured me that our legal situation is entirely different than the one in the California trial court case you referenced and does not align with the Commission’s legal situation in Maryland. We will continue to monitor legal developments in this area.

I suggest that the Parks Department periodically report its progress on its pesticide and glyphosate reduction programs to the Planning, Housing, and Economic Development (PHED) committee of the County Council, as the committee with oversight of Parks.

Thank you for your continued concern about the safety of our park staff and patrons. I can assure you that protecting our staff and the public is a value shared by our entire team.


Michael F. Riley

Director, Montgomery County Department of Parks



cc:        Montgomery CountyCouncilmembers

Casey Anderson, Chair, Montgomery County Planning Board

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