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Phos-Chek: Deadly to salmon, cautions for wine grapes, sketchy data on human effects, confusion among public officials

However, the sketchy and fragmented data available about the uncertain safety of fire retardant on wine grapes indicates that — even if safe — those should not be harvested or made into wine because of regulatory issues over unauthorized substances that might be detected in the finished products.


ALSO NOTE: No information could be found about on Sonoma County web sites pertaining to this issue.

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According to the warm and fuzzy (and unconfirmed) anecdotes about Phos-Chek, the bright-red, air-dropped chemical is so safe that firefighting instructors have supposedly been known to eat it on corn chips to show new recruits just how harmless it can be.


But the plural of anecdote does not equal data. And when it comes to  Phos-Chek, reliable data is sadly lacking.


There is no question that the fire retardant has played a vital role in saving lives and property in the wine country wildfires. However, the lack of reliable and complete data about it has complicated the lives of farmers impacted by the Wine Country wildfires.


No studies have been done in humans. No published, peer-reviewed studies have been done on laboratory animals. The main source of information is a document produced by the manufacturer.


And the only scientific article found during an extensive search of the scientific literature is a 2014 paper: “Toxicity of PHOS-CHEK LC-95A and 259F fire retardants to ocean- and stream-type Chinook salmon and their potential to recover before seawater entry” which found that small concentrations that are a fraction of that used in application will kill 50% of Chinook salmon.


  • “LC-95A is lethal to 50% of Chinook salmon at 0.23% of the applied concentration.”
  • “259F is lethal to 50% of Chinook salmon at 0.09% of the applied concentration.”


Adding to the confusion is the fact that there are many different formulations of Phos-Chek. Most share some form of fertilizer chemicals, and all of contain “trade secret” ingredients which are not disclosed.


The salmon study, cited above, is based on LC-95A and 259F formulations of Phos-Chek and not MVP-Fx as used in Napa. Because the information in the MVP-Fx data sheet is incomplete and lacking details, it is impossible to determine its effects on salmon.

Ag Commissioner Posts Caution, Deletes It

Wine Industry Insight received numerous calls and emails on October 23 asking where they could find the county advisory about fire retardant and wine grapes.


A search of the Ag Commissioner’s web site on Oct. 23 found no statement. When asked, the Ag Commissioner’s office told WII that they had not issued an advisory.


WII later learned on Monday — in an email from a private wine-related organization — that there had been a warning buried at the bottom of a lengthy Oct. 20 “Property Access Update” by the Ag Commissioner. See: Ag Commissioner posts caution on wine grapes and fire retardants on Oct. 20, then deletes it.


That notice may have been removed because, according to Scott McLean Cal Fire Deputy Chief of Information, he could find no one from Cal Fire who had had actually made that statement.


In a phone call to WII, Ag Commissioner Greg Clark agreed that the statement may have been made off the cuff in some meeting or another and had spread without it being any official word.

Napa Health Department Adds Caution

According to the Napa County Public Health Offices “Fire Retardant Safety and Removal Talking Points:”

Individuals are advised against consuming fruits and vegetables from home gardens to which retardant may have been applied, or from areas in wildlands where residues are visible.


In addition to avoiding consuming food items with visible residues, the fertilizer component of the retardants may lead to temporary increases in the nitrate content of soils in areas of application:
‒ Some vegetables are known to concentrate nitrates, particularly cauliflower, beets, spinach, broccoli, collard greens, carrots, turnips, and other root vegetables.
‒ Elevated levels of ingested nitrate could pose a risk upon conversion to nitrite, especially to infants who are more susceptible to methemoglobinemia.
In areas that were treated with retardants, individuals may harvest berries and mushrooms from wildlands after vegetative regrowth has occurred.

Phos-Chek-MVP-Fx — Safety (or lack thereof) in humans undeterminable

According to Scott McLean, Cal Fire Deputy Chief of Information, the Phos-Check used in Napa County was the MVP-Fx formula. He said that the Napa Ag Commissioner’s office was supplied an MSDS, Material Safety Data Sheet from Phos-Chek.


According to that MSDS data sheet, most of the ingredients are fertilizer compounds plus an undetermined percentage of secret ingredients which may or may not be relevant.


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The MSDS data sheet — which is not reviewed or approved by any government regulatory agency — says that tests on lab animals indicate that it is “practically nontoxic” or “No More Than Slightly Toxic.”


Unlike properly published, peer-reviewed scientific papers, this document created by the manufacturer based on results from a private lab offers no details on procedures or other details on how the studies were done. These sorts of studies are common and offer no oversight, no transparency and no controls over quality or integrity.


The following is from: Corporate & Federal Regulatory “Science”


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Source: Equal Treatment for Regulatory Science (PDF)

According to a landmark legal review of federal regulatory science created by the Boston University School of Law (Equal Treatment for Regulatory Science):


“Regulated parties who sponsor research that informs regulation of their products or activities have incentives to influence the research in ways that ensure favorable outcomes.”