Part 1 Neighborhood Coalition: Comments on Draft Environmental Impact Report and Cannabis Ordinance Amendments

July 14th, 2025

The Draft Environmental Impact Report to Disclose the Adverse Health Effects of Cannabis Emissions

The Neighborhood Coalition advocates for sustainable, environmentally sound, and neighborhood-compatible cannabis policies in Sonoma County in conjunction with education of the public on the health impacts of cannabis use. In addition to these comments, the Neighborhood Coalition is part of the county-wide coalition with Save Our Sonoma Neighborhoods. We endorse and incorporate by reference the comments filed by Shute Mihaly & Weinberger on behalf of Save Our Sonoma Neighborhoods.

 The purpose of CEQA is to disclose the environmental impacts of a proposed action to decisionmakers and the public. Disclosure is imperative when impacts threaten the health of neighbors near a commercial project. As discussed below, the DEIR contains multiple incorrect statements, erroneous calculations, and incorrect assumptions. It arrives at unsupportable conclusions on the safety of cannabis emissions and the carcinogen Beta-Myrcene without support in the scientific literature, actual measurements of emissions, and genuine toxicities that people experience. The utter failure of the DEIR to credibly address the health impacts of cannabis emissions demands rejecting its air quality section in its entirety and starting over.

Cannabis emits volatile organic compounds, primarily terpenes and thiols, which are responsible for its characteristic odor. The known carcinogen, Beta-Myrcene, can account for 50-70% of the volatile organic compounds. The strong smell isnoxious to most people. Residents living near cannabis cultivation sites whoare exposed to marijuana emissions often experience adverse health effects and serious medical symptoms such as nausea, headaches, vomiting, difficulty breathing, coughing, eye irritation, sore throat, respiratory irritation, and sleep disruption. People with asthma are particularly vulnerable to this impact, and cannabis can cause new cases of asthma. Workers have died from being exposed to cannabis emissions in Massachusetts and California. Sonoma County residents have experienced these deleterious effects. Demonstrative of the deleterious effects of the cannabis emissions, cannabis workers typically wear moon suits to protect themselves from exposure.

Terpenes incannabis emissions react with the air to form formaldehyde (a carcinogen), formic acid, and high levels of ground level ozone. Each is a human irritant. See“ Cumulative Levels of Beta-Myrcene Inhaled by Humans Living Near Outdoor Cannabis Cultivation Sites May Be Toxic and Carcinogenic” (“NC Beta-MyrceneReport,” Attachment 1, p. 1). Ozone can cause nausea, burning of eyes and throat, coughing, and respiratory distress. The DEIR states (Table ES-1, Impact3.3-3) that cannabis cultivation sites do not create ozone precursors exceeding BAAQMD thresholds. While true this is misleading and irrelevant. But BAAQMD regulates regional ozone over broad geographical areas; it does not regulate local ground level production of ozone near cannabis cultivation sites. The DEIR fails to mention, let alone analyze, this significant air quality issue.

The DEIR acknowledges that cannabis emissions are a problem, but contends it is merely an inconvenience.DEIR p. 3.3-11. The DEIR belittles or ignores the health and toxic effects of cannabis emissions. The DEIR’s fundamental approach is misguided, as exemplified by stating it will “consider” rather than ensure the protection of public health and safety” (DEIR, ES-2,emphasis added). Both the discussion of “significant and unavoidable adverse impacts” (section 6-2), and its proposed statement of overriding considerations for air quality for Supervisors to consider are disingenuous:

·        “Expose a Substantial Number of People to Odors Considered Objectionable.” (DEIR, p. 6-3, emphasis added).

An objective assessment of the health effects of cannabis emissions would require rephrasing the finding to be scientific and accurate as follows:

·        “Expose a Substantial Number of People to Odors that Cause Adverse Health Effects, Including Cancer.”

The Neighborhood Coalition’s NC Beta-Myrcene Report analyzed the scientific literature and provided the report in 2024 to the Sonoma County Health Department, Permit Sonoma, the Planning Commissioners, and the Board of Supervisors. It found that outdoor cannabis cultivation is likely to cause significant toxicities and even cancers to all residents, even more for children, the infirm, and the elderly. These levels can be reached in as little as 3 months for small children, and less time for babies and developing fetuses. As discussed below, the report was validated by three outside independent scientists each of whom has outstanding credentials and at least three decades of relevant experience.

The marijuana industry claims that cannabis emissions are just another agricultural odor. Rural residents should either accept breathing cannabis emissions in their homes ormove somewhere else. This ignores the fact that the State of California has determined that Beta-Myrcene is carcinogenic. Our issue paper “Unlike Typical Agricultural Odors, Cannabis Odors Pose Health Risks” (Attachment 2) debunks theclaim that all agricultural emissions are equal. Emissions from poultry and cow manure consist of hydrogen sulfide, methane, and carbon dioxide. Unlike the terpenes Beta-Myrcene and D-Limonene in cannabis emissions, manure does not emit carcinogens. See “Comments on Odor, Nuisance and Trinity andSafe Bridge Reports in the Sonoma County Cannabis Draft Environmental Impact Report,” p. 2 (“Eppstein Report,” Attachment 3).

As described in “What’s it Like to Live 100 feet from 15,000 Cannabis Plants?,” neighbors living near outdoor cannabis often cannot open their windows or use their yards for months each year. They are forced to breath air contaminated with cannabis emissions including Beta-Myrcene, 24 hours a day, 7 days a week. The level they inhale is toxic and, in many cases, carcinogenic.

Dr. Alan Cohen, a pulmonaryphysician and scientist, emphasizes that cannabis emissions “are not innocuous substances that simply make the air smell ‘skunky’ and unpleasant, they carry meaningful health risks that need to be cautiously accounted for when considering allowances for commercial level cultivation of cannabis in unenclosed agricultural areas” (Cohen Report, Attachment 4).

Appendix C to the DEIR includes two studies on cannabis emissions issues by Trinity/ Safebridge:  (1) Occupational Exposure Limit (OEL)Monograph for Beta-Myrcene (“OEL Report”) ; and (2) Modeling to Estimate Ground-levelBeta-Myrcene Concentrations (“Modeling Report.”) No consultant for the DEIR has medical, pharmaceutical, or public health experience. The DEIR neither mentions nor discusses invoking the precautionary principle when public health and safety are at stake. No public health professional would confine the focus of a study to healthy adults and ignore sensitive receptors such as children, infants, the infirm, and the elderly. This is especially true when about half of Sonoma County’s population are children or elderly (Eppstein Report, p. 7). Both California and the federal EPA set clean air standards to protect the health of sensitive populations such as asthmatics, children, and the elderly.

I.                  The “Safe Exposure” Levels That the Occupational Exposure Limit (OEL) Report Proposes Are Understated by Orders of Magnitude.

The OEL Report is replete with erroneous assumptions and errors. In aggregate, its errors led itto vastly understate the toxicity and carcinogenicity of cannabis emissions. Dr.Cohen concludes (p. 2) that its assumptions regarding human exposure and risk are not “remotely fair-balanced and accurate,” especially regarding the “exposure of children and more vulnerable infirmed and elderly adults.” Error upon error compoundsto such an extent that the OEL Report’s predictions bear no resemblance to reality. “The true exposure risks are clearly significantly unhealthy, highly problematic, and unsupportable.” Cohen Report, p. 3.

One error isassuming that ingestion of terpenes and Beta-Myrcene provides the same exposureas inhalation. Nothing could be further from the truth. Dr. Srinivasan Venkatehwwaran, who has 35 years of experience in the pharmaceutical industry focused on administering drugs using oral, transdermal, and inhalation methods, emphasizes that inhalation of chemicals, unlike eating them, maximizes bioavailability (VenkatehwwaranReport, Attachment 5). “Brain exposure of a molecule via the blood can be significantly lower than exposure resulting from direct brain exposure of the molecule by inhalation because of metabolism, distribution into other bodyorgans/tissues and difficulty in crossing the blood brain barrier.” Id. Regarding the animal studies that lead to the listing of Beta-Myrcene as a carcinogen, “exposureby inhalation may cause brain toxicities not seen in the rodent toxicity studies” because no animal toxicity studies have studied inhalation (VenkatehwwaranReport, p. 2). Dr. Cohen, whose 35 years of experience has focused on pulmonaryhealth, agrees. The Cohen Report (p. 3) estimates that assuming bioavailability when inhaling instead of ingesting Beta-Myrcene are identical underestimatessafe exposure by 3 to 5 times; Chayasirisobhon, S. Mechanisms of action and pharmacokinetics of cannabis. Thus, the DEIR’s calculated “safe” dose needs to be reduced by a factor of 3 to 5 based on this fallacy alone because all animal toxicity studies were conducted by feeding the animals.

A second error is assuming exposure in homes occurs only 8 hours rather than 24 hours per day, especially for vulnerable populations. Cohen Report, p. 2. Safebridge’s “safedose” would need to be reduced by a factor of 3 based on this error alone.

A third major erroris the failure to analyze a safe dose for anyone but a “typical” healthy 70 kg (154pound) adult. Toxic levels are determined by body weight, and small children inhale the same daily volume as do adults. The safe dose for a 14 kg (31 pound) child would be one-filth that of an adult and an infant one twentieth. Dr. Cohen suggests that Safebridge’s “safe dose” for a fetus might would need to be reduced by a factor of 100.

Toxic levels were determined from the amount that caused cancer in mice and rats, using established factors used by the pharmaceutical industry and the FDA to convert a dose froma rodent to a human. The factors account for differences such as bodychemistry, metabolism, body surface area, and pharmacokinetics. Safebridge’s “safe dose” is based on the lowest dose tested in the rat carcinogenicity studyand ignores the mouse studies. Both studies showed “clear evidence” of carcinogenicityat the lowest level tested and no lower safe dose was determined. Using the mouse study instead of the rat study as their starting point would reduce Safebridge’s “safe dose” by half. The lowest dose tested in rats and mice was carcinogenic and thus no safe dose was determined. Using established factors used by the pharmaceutical industry and the FDA, that dose should be reduced by another factor of at least 10-fold on top of all the above reductions, to account for the unknown safe dose level in animals.

SafeBridge calculated the same occupational exposure limit from the two-year rat study, where the lowest dose was carcinogenic, as from a three-month study in rats done to support the food flavoring industry, where Beta-Myrcene was dosed inthe feed. This discrepancy highlights the importance of using the results of the longer-term study to evaluate potential toxic and carcinogenic effects in humans and omits consideration of the far more potent impact of air-borne Beta-Myrcene.

The OEL Report (p. 2) attempts to discredit the rodent studies that are the basis for California’s Office of Environmental Health Hazard Assessment determining that Beta-Myrcene is carcinogenic to humans. It makes the subjective claim that animals were exposed to “extraordinary high levels” of Beta-Myrcene. The OEL Report ignores the fact that the toxic dose in rodents relates to a much lower human toxic dose. As detailed in the NCBeta-Myrcene Report, the lowest dose tested in mice, which was both toxic short term (70 days) and carcinogenic after 2 years, converts to a human dose-equivalent that is in projected toxic levels of exposure from outdoor cannabis emissions (Eppstein Report, p. 4). Claiming such levels are “high” is misleading.They are “high” only in comparison to the very low levels that are consumed as food additives and flavorings. The levels of Beta-Myrcene in food flavorings are orders-of-magnitude lower than human exposure to outdoor airborne cannabis emissions where neighbors are forced to inhale “extraordinarily high levels” of Beta-Myrcene. When humans inhale 100 ppb Beta-Myrcene daily, this equates to drinking 1,400 beers or eating 300 pounds of carrots per day (Eppstein Report, p. 3).

Another deficiencyin the DEIR is consideration of increased carcinogenicity potential of Beta- Myrcenein conjunction with other compounds in the cannabis emissions. There have been no safety studies conducted with the mixture of terpenes and other components of cannabis emissions. As noted above, both Beta-Myrcene and d-Limonene are known to cause cancer in animals, but the other cannabis terpenes have not been tested. Mixtures of compounds can be synergistic in toxicity and carcinogenicity. Cancer often results from a progression of mutations, and combination of two or more separate mutations is synergistic in accelerating onset of cancer. This big unknown is further reason to reduce the allowed exposure levels to far below the known toxic level of Beta-Myrcene as an isolated compound, to help protect from synergistic toxicities from othercarcinogenic compounds in (e.g., d-Limonene) or formed by (e.g., formaldehyde) cannabis emissions. As an analogy, both second-hand tobacco smoke and cannabis smoke are carcinogenic. Tobacco smoke contains over 7,000 compounds of which atleast 69 are known carcinogens, including formaldehyde, which is one of the secondary pollutants from cannabis terpenes. Second-hand cannabis smoke also contains many of these same carcinogens. The cancer-causing potential of Beta-Myrcene in combination with the other compounds in cannabis emissions has not been tested but may well be greater than that of Myrcene alone.

In sum, the OEL Report lacks credibility. It should be disregarded because it provides no evidence to support any decision by the County concerning the health effects of cannabis emissions. No non-toxic, non-carcinogenic level of exposure to Beta-Myrcene hasbeen established. Any objective assessment of the facts leads to the conclusion that outdoor commercial cultivation poses a serious health hazard to adults, children, the inform, and fetuses (Venkatehwwaran Report, p. 4).

II.               Trinity’s Theoretical Air Dispersion Modelsto Estimate Beta-Myrcene Concentrations Are Wrong and Contradict Empirical Measurements.

The DEIR includes no measured emissions. Instead, it employs a theoretical air dispersion model to estimate cannabis emissions, especially Beta-Myrcene. The Modeling Report’s calculations to estimate emissions cannot be replicated. Dr. Mark L. Kram, who has 40 years of experience using innovative environmental assessment techniques, notes that “a model is only as reliable as its weakest assumption . . . it would be helpful to be transparent about every assumption used in each simulation, and to perform sensitivity analyses to understand critical controlling factors and impacts on exposure predictions” (Kram Report,Attachment 6). No sensitivity analyses were conducted.

While models can be helpful for understanding processes, empirical evidence is far more reliable to as certain actual cannabis emissions levels. Sonoma County has had plenty of opportunities to collect empirical cannabis emissions data. Since 2019 we have recommended that Permit Sonoma use mobile gas chromatographic quantitation to measure terpene emissions to provide objective information about cannabis emission levels. In 2024 the Neighborhood Coalition wrote to Permit Sonoma requesting it measure cannabis emissions scientifically using off the shelf, established technology (Attachment 7). During a Board of Supervisors hearing in May 2024 staff represented they would address this issue in the DEIR. “Addressing this issue”did not include making any empirical measurements. We surmise that PermitSonoma prefers to engage in data-free debates and is concerned, impliedly, that genuine emissions data might be an insurmountable barrier to the County’s policy goals.

The Kram Report (p.1) underscores the limitations of Trinty’s approach. “Calibrated simulations based on data collected from a few select operations either within Sonoma County or from other regions with similar characteristics would have been useful and potentially more applicable.” Unlike the County, Dr. Kram does have measured cannabis emissions data from Santa Barbara County. In addition, he estimated levels of cannabis emissions from the observations in Kern County and Nevada County where cannabis emissions were reported two miles and one mile away, respectively. DEIR, p. 3.3-12.

The DEIR (p. 3.3-12) wrongly states “there is not a clear or consistent numerical threshold to use for cannabis odors.” How the authors of the DEIR would know anything about a numerical threshold for cannabis emissions is a mystery, because they either have no emissions data or the emissions data they have cannot be disclosed because they do not advance the policy goals of the County. The Kram Report (p. 2) provides such information based on a human odor detection threshold used for more than 40 projects in Santa Barbara County. When “terpene concentrations range between 20 and 50 ppb, greater than 50% of the participants report odors.”

The Modeling Report’s estimated level of Beta-Myrcene at the edge of a 1-acre grow is so low (Figure 1 in Modeling Report, 0.116 mg/m3, equivalent to 19 ppb) that it must be rejected out of hand. This level can only be detected at most by half of people (threshold of odor detection where 50% of people can detect cannabis is 20-50 ppb terpenes), which is inconsistent with human experience in Sonoma County. According to the Modeling Report, no one can smell cannabis emissions unless they are at a cultivation site, and no one would ever have had any reason to complain about cannabis emissions in their homes or on their property. In stark contrast to the Modeling Report’s fantasy world, residents have endured multiple and immediate physiological effects, including nausea, headache, respiratory distress, coughing, aggravation of asthma, hundreds of feet from a 1-acre outside cultivation field. See, e.g., What’s it Like to Live 100 feet from 15,000Cannabis Plants? The Modeling Report table provides identical levels at the fence-line and at 100 feet, which is inconsistent with the air dispersion model. We cannot fathom what the Modeling Report’s results mean, but they are surely useless in evaluating cannabis emissions.

The Modeling Report is also internally inconsistent regarding a graph from the 2020 Yolo EIR (DEIR, Figure 3.3-3) which was also authored by the same consultant. That graph shows significantly higher levels of terpenes at the fence line (40 Odor Units, about 800-2000 ppb), at 100 feet (25 OU, about 500-1250ppb), and 600 feet (about 8 OU, or 160-400 ppb) from a 1-acre cannabis field. These levels are well above toxic and carcinogenic levels.

The Kram Report,Table 1, p. 4 summarizes the inconsistencies of the Modeling Report’s simulations with empirical field measurements. The Modeling Report predicts a Beta-Myrcenelevel for a 10-acre grow at 600 feet of 16 ppb, while Dr. Kram’s measurements at a 4-acre grow at 2,600 feet found 439 ppb. The Modeling Report’s numbers are likewise inconsistent with the Kern County and Nevada County reports, where odors in the 20-50 ppb range were detected 1 and 2 miles away from the cultivation site. Kram Report, pp. 2-3. “These inconsistencies point to the critical need for site-specific empirical assessment with confirmation testing.” Kram Report, p. 4. Because the Modeling Report’s conclusions contradict empirical measurements, they must be rejected.

A reference exposure level (REL) is “an airborne level of a chemical at or below which is considered safe for people to be exposed to every day for their entire lives without any health problems.” Modeling Report, p. 1. This is what is considereda safe dose. The Modeling Report proposes a safe dose of 0.5 mg/m³ (equivalent to 82 ppb) and, as discussed above, should be orders of magnitude lower lower. The Modeling Report’s predicted terpene concentrations at key distances from operations are substantially lower than those measured by Dr. Kram as well as those reported by others based on odor threshold relationships to terpene concentrations (e.g., Kern County, 2017; Nevada County, 2019). Kram Report, p.1.

Concentrations of Beta-Myrcene are expected to be higher at larger distances from operations than the Modeling Report predicts. If a person smells odors at 1,000 feet or greater from an operation, they are probably inhaling levels of Beta-Myrcene that exceed the safe dose. See examples in Kram Report, pp. 5-6. Insum, it would be error for Commissioners and Supervisors to rely on the erroneous results in the Modeling Report or the OEL Report. They lack credibility and cannot withstand scientific scrutiny to be used as evidence to support any decision by Sonoma County.

Finally, Dr. George Rutherford, a distinguished Professor Emeritus at the University of California San Francisco, concluded that the County should “seriously consider the toxic and carcinogenic effects of Beta-Myrcene to which residents are exposed involuntarily and act in a way to protect the public health.’ (Attachment 8). Dr. Rutherford is a former State Epidemiologist and State Health Officer for California as well as a current professor of Epidemiology, Preventive Medicine, Pediatrics and History, with over 300 peer-reviewed publications. Sonoma County officials should heed his advice if they have any concern for the public health of its residents. Dr. Rutherford’s expert opinion constitutes presumptive medical evidence of the County’s obligation to meaningfully address and mitigate the Beta-Myrcene threat to the public posed by cannabis emissions.

Thank you for considering and hopefully implementing our comments.

Neighborhood Coalition

Nancy and Brantly Richardson, Communications Directors

SonomaNeighborhoodCoalition@gmail.com

 Find  attachments in link to original article above:

Attachment 1.  Neighborhood Coalition, Cumulative Levels ofBeta-Myrcene Inhaled by Humans Living Near Outdoor Cannabis Cultivation Sites May Be Toxic and Carcinogenic” (October 18, 2024).

Attachment 2.  Neighborhood Coalition, Unlike Typical Agricultural Odors, Cannabis Odors Pose Health Risks” (May 21, 2024).

Attachment 3.  Deborah Eppstein, Comments on Odor, Nuisanceand Trinity and SafeBridge Reports in the Sonoma County Cannabis Draft Environmental Impact Report” (June 27, 2025).

Attachment 4.  Letter from Dr. H. Alan Cohen (June 25, 2025).

Attachment 5.  Letter from Dr. Srinivasan Venkatehwwara to Board of Supervisors (June 27, 2025).

Attachment 6.  Letter from Dr. Mark L. Kram to Board of Supervisors (July 9, 2025)

Attachment7.  Neighborhood Coalition, Letter to Permit Sonoma (May 10, 2024)

Attachment 8.  Letter from Dr. George W. Rutherford to Board of Supervisors (November 6, 2024)

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