The Radioactive Fertilizer Hoax


The Munging Down of Science



This is an extract from some new material that I am putting together for an upcoming edition of Integral Hydroponics. This particular extract (part of a much larger piece discussing hydroponic and organic growing methodologies) was inspired after a friend from BC mentioned that he was concerned about the use of inorganic (“chemical”) nutrients/fertilizers because as far as he understood, inorganic fertilizers are radioactive. I initially laughed at this comment, having never heard it before, and then went looking for the source of the information.


What I found shocked me. That is, with the readership in mind, there was information all over the web that originated from a single source, David Malmo-Levine, who writes for Cannabis Culture Magazine, and in January of 2002 went on a mission to demonize inorganic (“chemical” in his words) fertilizers.


This is my response to his work – which I must say somewhat impressed me. I.e. he has been parroted across the net by multitudes of article spinners with, among other largely unsubstantiated claims, that it is radioactivity (in the form of polonium-210) caused by the use of agrichemical phosphate fertilizers, not  the 70 or so other known carcinogens in the tobacco smoke stream, all of which are capable of causing cancer on their own, along with numerous carcinogen precursors etc, that is “probably causing 90% of cancer in smokers.”  According to Malmo-Levine this is a fact because the US Surgeon General, C. Everett Koop, stated this on US National Television at some point during 1990 . The only problem being that, other than the fact that this alleged statement is/was not scientifically supported,  the Surgeon General in question resigned on October 1 of 1989 (an all too obvious point that all seem to have missed – see US Government past Surgeon General’s link also at Basically, however, the quality of information went downhill from there.


Among other things, Malmo-Levine then promoted carcinogenic organic tobacco as a safe alternative to carcinogenic inorganic tobacco – an act as you’ll come to see, based on his own flawed logic, tantamount to promoting radioactive death to thousands of tobacco smokers. That is, there is every chance that commercially available organic tobacco possesses higher radioactivity values (in the form of polonium-210) than inorganically grown tobacco. Not that this likely matters too much because tobacco without polonium-210 is still deadly. As the American Cancer Society points out:  “All smoke from cigarettes, natural or otherwise, contains many agents that cause cancer (carcinogens) and toxins that come from burning the tobacco itself, including tar and carbon monoxide.”


While the Stanford School of Medicine notes: “Clearly, perceived health benefits of natural cigarettes are still rampant in mainstream popular culture, a dangerous misconception.”


See links re “Radioactive Tobacco” by David Malmo-Levine:


Later that year the same man set out to prove that “chemical” fertilizers are radioactive (possibly as a result of Imperial Tobacco threatening to sue him) and then went live with  “Radioactive Buds?”. Now pot, it seemed, according to Malmo-Levine, if grown with “chemical” fertilizers, was radioactive also  (the story first featured on Cannabis Culture Magazine in December of 2002, 11 months after his ‘Radioactive Tobacco’ expose’). Again, as with his radioactive tobacco lambasting, this largely misinformed hyperbole was then spammed widely across the internet and taken as fact/proof by many that inorganic fertilizers are highly radioactive stuff and could be causing cancer in pot heads. Oh the horrror! The horror! (cough… cough….hack…hack)
See orignal radioactive fertilizers story:


Anyway, beyond the hype, let’s take a look at the science.


Inorganic Fertilizers are Radioactive


There is some basis to this claim, although it tends to be greatly overstated, misrepresented and/or completely misunderstood by those who typically assert it.


This said, it is shown that some inorganic fertilizers potentially have somewhat higher radioactivity levels than organic fertilizers. For instance, agrichemical phosphate fertilizers are shown to possess higher levels of radium-226 than organic phosphate containing manures. However, where organic phosphate rock fertilizers (e.g.  Flouropatite –  [Ca5(PO4)F]) are used, which is a very common practice in organic farming, even higher levels of radioactivity are likely to be present in soils than where agrichemical phosphate fertilizers are used. We’ll cover more on this shortly.


On the point of oversimplified, firstly, both organic and inorganic fertilizers are naturally radioactive and, secondly, naturally occurring radioactive materials (NORMS) are found in every constituent of the environment; air, water, soil, food and in humans. There is nowhere on earth that you cannot find natural radioactivity. Our world is radioactive and has been since it was created.


For instance, carbon – the key element of organic chemistry and a key element in organic farming, an element that is essential to life, is radioactive. Carbon is the sixth most abundant element in the universe. Carbon-14 is the radioactive isotope of carbon with a half-life of 5,730 years. The amount of carbon-14 in the environment remains constant because new carbon-14 is always being created in the upper atmosphere by cosmic rays. Living things tend to assimilate materials that contain carbon, so the percentage of carbon-14 within living things is the same as the percentage of carbon-14 in the environment.


All of us have a number of naturally occurring radionuclides within our bodies. The major one that produces penetrating gamma radiation that can escape from the body is a radioactive isotope of potassium called potassium-40. This radionuclide has been around since the birth of the earth and is present as a tiny fraction of all the potassium in nature.

Potassium-40 (40K) is the primary source of radiation from the human body for two reasons. First, the 40K concentration in the body is fairly high. Potassium is ingested in many foods that we eat and is a critically important element for proper functioning of the human body; it is present in pretty much all the tissues of the body. The amount of the radioactive isotope 40K in a 70-kg person is about 5,000 Bq (becquerel), which represents 5,000 atoms undergoing radioactive decay each second. Besides potassium most of the rest of our bodies’ radioactivity is from radioactive carbon and hydrogen.


All food sources combined expose a person to around 40 millirems of radiation per year on average. You’ll note the different forms of radiation measurements – nuclear physics unfortunately is extremely complex (a point too many miss); however, to simplify and explain the different terminology, a millirem is a measurement of the dose of radiation, while a becquerel is the measurement of the amount (measured at rate of decay per second) in a given material/mass.


Many foods are naturally radioactive, bananas particularly so, due to high potassium levels and, therefore, the radioactive potassium-40 they contain. The equivalent dose for 365 bananas (one per day for a year) is 3.6 millirems. As a piece of trivia, the radioactivity from a truckload of bananas is capable of causing a false alarm when passing through a Radiation Portal Monitor used to detect possible smuggling of nuclear material at U.S. ports.


Anyway, to put things into context, on average our annual radiation exposure from all natural (e.g. cosmic radiation) and man made sources (e.g. pollutants, medical procedures) can be anywhere between, on average, 400-  600 milliRem. This said, the radiation dose for increased cancer risk for 1 in 1000 is stated to be at 1,250 milliRem, while the earliest onset of radiation sickness in a person would require approximately 75,000 milliRem of radiation.


Most radioactive substances enter our bodies as part of food, water or air. Our bodies use the radioactive as well as the nonradioactive forms of vital elements such as iodine and sodium. Radioactivity can be found in all foods and even in our drinking water. In a few areas of the United States, for instance, the naturally occurring radioactivity in the drinking water can result in a dose of more than 1,000 millirem in one year.


Coming back to claims of radioactive fertilizers – potassium in fertilizers, whether in organic or inorganic form, is a source of radionuclides. There are three potassium isotopes: K39, a stable isotope, is the most abundant, at 93.26 % of the total; K41 is next in abundance at 6.73 % and is also a stable isotope. The isotope in question is the radioactive isotope, K40. It is present in all potassium at a very low concentration, 0.0118 %. The higher the level of potassium in the fertilizer, the higher the concentration of potassium-40.  Slightly elevated levels of rubidium-87, a pure beta emitter, have also been reported in potassium fertilizers – rubidium and potassium have similar chemistries.


The most problematic source of radioactivity in fertilizers is phosphate rock, mainly due to Radium-226 (226Ra). Radium-226 breaks down into two long lived ‘daughter’ elements — lead-210 and polonium-210. Phosphate rock contains radionuclides in concentrations that are 10 to 100 times the radionuclide concentration found in most other natural material, although the average uranium (U) content in phosphate rock is low at 50-200 parts per million (ppm) or 0.005-0.020 percent. For comparison, some Canadian commercial uranium rich ores contain up to 15 percent or 150,000 ppm of U.


The problem is that phosphate rock is used as a source of P in producing inorganic phosphorous fertilizers. However, phosphate rock is also commonly used by organic growers as a source of P in organic agriculture. An example would be the use of mined natural rock phosphate which contains phosphorous in the natural mineral form of Flouropatite [ Ca5(PO4)F ]. Flouropatite is a widely used source of phosphate in organic agriculture. In fact, the use of phosphate rock is seen as a best practice source for P and other macro and micro elements by many organic growers. For instance, as the Australian Government Rural Industries and Research Corporation states in ‘Fertility Management in Broad-Acre Organic Cropping’:


 “Rock phosphate is perhaps the only practical fertiliser that farmers may employ for sustaining soil phosphorus in broad-acre, rain-fed organic agricultural systems, given that superphosphate use is disallowed.”  (Evans. J. 2010)


On the other hand, phosphate rock is used to produce many conventional inorganic phosphate fertilizers, basically by acid extraction solublising the phosphate ion (PO43-) with sulphuric or phosphoric acid.


This is where things get somewhat interesting. The fact is that agrichemical phosphate fertilizers derived from phosphate rock theoretically (very likely) produce far less radioactivity in soils than their organic equivalents (e.g. Flouropatite) when used at volumes to achieve the same levels of available P (ppm) per hectare. This is because treated inorganic phosphate fertilizer has higher % P content than untreated organic phosphate rock. For instance, while the P levels vary in different phosphate rock samples research compiled by the International Atomic Energy Agency (2002) showed variables ranging from 15–17% (Russia, Chile) to 35–36% (Senegal,Togo), with an average of 27% P205. Comparatively, inorganic phosphate fertilizers typically contain between 40 – 50% P205, with more pure products at around 60% P205 or, generally speaking, about twice the P205 as their organic equivalents. Compound this with the fact that organic rock phosphates take a long time to break down into plant available inorganic phosphorous (as a result of soil/microbial interaction); therefore, far higher levels of organic phosphates are needed to achieve the same outcomes. For instance, when compared with phosphorus supplied as agrichemical superphosphate, 10 times as much phosphorus as organic rock phosphate may be needed to produce the same yields at low levels of application and 100 times at higher levels of application.


Another significant factor that comes into play is that a percentage of the radioactive materials are leached from the phosphate rock during the processing of agrichemical P fertilizers and a purified form of phosphate, with a high degree of the radioactive contaminants removed, is produced. The amount that is removed will depend on original concentration of radioactive material and the treatment process. However, when phosphate rock is treated during manufacture of fertilizers a by-product of the process, which is discarded/stock piled, phosphogypsum, ends up containing around 60 times the background levels in soil for radium-226. Additionally, research has shown that the activity concentrations of 232Th and 226Ra were reduced during the processing of phosphate rock into phosphate fertilizers to 1/8th (12.5%) and 1/4th (25%) of their activity concentrations in rock phosphate. (Sahu. S. K et al, 2014)


While, data on comparative analysis of radium-226 contribution by inorganic and organic phosphate fertilizers to soils is scant, to say the least, research by Jibiri et al (2010) compared the radioactivity in fertilizers using phosphate rock as the raw material and untreated phosphate rock samples and found that concentrations of radium-226, thorium-232 and potassium-40 in the untreated phosphate rock samples were “10 orders of magnitude higher”.


Additionally, a research paper prepared by Florida State University for the Florida Institute of Phosphate Research (1988) provides some insightful information about polonium-210 levels in phosphate rocks and its environmental fate. Firstly, the research showed that significant portion (up to 60%) of the radioactivity within weathered phosphate rocks is located within the finest sized material. Notably, the phosphate rock used in organic agriculture is finely ground – as a rule the smaller/finer the particle size the more readily P becomes available in soils. Secondly the research concluded that radium-226 appears to be leached more readily from phosphate rock samples by, among other things, double-deionized water and humic acids. Notably water and humic acids are highly regarded by organic growers and plants. Thirdly, they discovered that after the host matrix (material) is weathered and leached by groundwater, uranium and radium-226 can be readily solubilized, transported, and deposited quite far away from the host material matrix. Radium-226 does not occupy regular lattice positions within uranium-bearing minerals. Therefore, it enters groundwater (e.g. rivers) more readily. Lastly, they tested water wells that were in proximity to phosphate rock deposits and discovered polonium-210 values greater than EPA limits in every well they tested.


In most of our samples, the concentrations of 210P0 commonly range from <0.1 to 10’s pCi L-1, activities of 100’s pCi L-1 are found in a few cases and more than 2,000 pCi L-1l was found in one unfiltered sample.”  (Burnett. W. C et al 1988)


With regards to the far higher radioactivity values of organic rock phosphate fertilizers, when compared to their agrichemical equivalents, and the fact that to achieve the same P levels in soils, at even moderate levels, requires 10 times more phosphate rock, this gives us a value of about (conservatively) 50 times the radiation from sources such as polonium -210 in organic farm soils. With this in mind, David Malmo-Levine, in his lambasting of “Radioactive Tobacco”, promotes organically grown tobacco as a safer alternative to inorganically grown tobacco with:




“Tobacco smokers can also use this information to avoid radioactive brands of tobacco. American Spirit is one of a few companies that offers an organic line of cigarettes, and organic cigars are also available from a few companies. You can also grow your own tobacco, which is surprisingly easy and fun.”


[End Quote]


Let’s just hope that American Spirit tobacco isn’t grown using organic rock phosphate fertilizers David, because if it is, based on your own logic, you’ve just promoted radioactive death to thousands of smokers.  How about this – smoking organic or inorganically grown tobacco will very likely damage your health (best case scenario) or kill you (worst-case scenario), radioactive or not. I.e. it seems to me that promoting any form of tobacco company, while paying out on tobacco companies, sends a very mixed and highly confused message indeed (cough, cough, hack, hack!). Moving on…


Basically, however, the most problematic radioactive fertilizer, phosphate rock fertilizer, whether organic or inorganic, equates to about the same thing (i.e. ‘radioactive fertilizers’), albeit that organic (untreated) phosphate rock fertilizers potentially/theoretically produce far higher radioactive values in soils and solution than their agrichemical counterparts.


So what happens when we remove phosphate rock from the fertilizer equation? Do we then have non-radioactive fertilizers? Well, not quite – albeit somewhat better, which, given the science, would be expected.


Research in Saudi Arabia compared a total of 30 samples: 20 phosphatic fertilizers and 10 organic fertilizers (cow, sheep and chicken) collected from markets and farms. The activities of 226Ra, 232Th and 40K in natural fertilizers (cow, sheep and chicken) were lower than the activities in inorganic fertilizers. The data was compared to available reported data from other countries in literature. The radium-226 in inorganic fertilizer ranges from 100.37 to 161.43 Bq kg−1 and in organic fertilizer ranges from 34.07 to 102.19 Bq kg−1, which in both cases are lower than the safety limit of 370 Bq kg−1. (El-Taher. A. 2012)


In other research, uranium (U) concentrations were analyzed in a set of inorganic fertilizers with and without phosphorous (P) and compared to U concentrations in various organic fertilizers (non phosphate rock manures). Mean concentrations between 6 and 149 mg/kg U were found in P containing inorganic fertilizers, while mean concentrations in inorganic fertilizers without P were below 1.3 mg/kg. Mean U concentrations in farmyard manures did not exceed 2.6 mg/kg. As a consequence, an average P dressing of 22 kg/ha P would charge the soil with up to 17-61 g/ha U when added as an inorganic fertilizer but less than 10 g/ha when applied as farmyard manure or slurry. (Kratz. S and Schnug. E. 2006)


Comparison of Radioactivity in Organic and Inorganic Fertilizer Products


The radioactive fertilizer debate amongst the indoor growing community largely stems from a single study conducted by Dr Paul Hornby and David Malmo-Levine. This study was then disseminated and circulated widely with, among other claims:


“A recent study shows that many commonly used fertilizers are high in radioactive elements. The study was performed by Dr Paul Hornby, who holds a master’s degree in biochemistry and a PhD in human pathology from the University of British Columbia.


There are different ways of measuring radioactivity. The chart below shows the “counts per minute” (CPM) of radiation detected in each sample. The average for the organic fertilizers was 140, while the chemical fertilizers had an average radiation count of 675, an almost five-fold increase.


The lowest radiation was found in the organic blood meal fertilizers, which emitted only background radiation, the normal low radiation found in most objects. On the other end of the spectrum was the 5-20-20 berry food, with a radiation level about 24 times higher than background.


Numerous studies published in the New England Journal of Medicine and other health, science and radiation journals have indicated that it is the radioactive elements in tobacco which lead to lung cancer (CC#35, Radioactive tobacco). Tobacco is typically fed with high-phosphate, chemical fertilizers, including heavy foliar spraying. All of these factors would produce a high-level of radioactive elements in the tobacco leaf.


Although further research is needed, this study does point the way to some simple harm-reduction techniques for growers. Many growers believe that using organic fertilizers produces a tastier, higher-quality product. This study indicates that they could also be producing a less harmful product than that produced with many chemical fertilizers.”


And so on….


Just quickly, to expand on the numerous studies that have indicated it is the radioactive elements in tobacco which lead to lung cancer – this relates to the radioactive element poloniom-210 which some studies have shown could possibly be contributing to, along with the other 70 or so known carcinogens in tobacco, all of which are capable of causing cancer on their own, playing some role in causing cancer among smokers (albeit, the research could not assess the actual risk).


So, let’s analyse the data.


See following results:


Organic Fertilizers


Fertilizer Type……………………………………..Radioactivity score

Evergro Specialty Fertilizer……………………..90
Blood Meal 12-0-0

Green Valley…………………………………………….96
Blood Meal Fertilizer

RainGrow Organic Fertilizer…………………….102

SeaSpray Organic Fertilizer……………………..125

Green Valley Blood and Bone……………………..154
Meal Fertilizer

RainGrow Organic Fertilizer……………………..160

Homestead 100% Organic…………………………..174
Bone Meal

DML Bird Guano………………………………………..178
NPK unknown

Inorganic Fertilizers
Fertilizer Type……………………………………..Radioactivity score
Miracid Soil Acidifier……………………………..248
Plant Food

Shultz All Purpose Plant Food…………………..258

Miracle-Gro For Roses……………………………..285

Green Valley…………………………………………….326
Rhododendron and Azalea Food


Shultz African Violet Plus……………………………..393

General Hydroponics……………………………………….400
Flora Grow

Miracle-Gro Water Soluble…………………………….409
Plant Food

Greenleaf Evergreen………………………………………..437
Tree and Hedge Feeder

Stern’s Miracle-Gro……………………………………….538
For Tomatoes

Plant Food Engrais

Greenleaf Shur Gro…………………………………………….672
Soluble Plant Food

Greenleaf Shur Gro…………………………………………….693
Soluble Plant Food

Orchid Plant Food

Shultz Tomato Plus…………………………………………….874

Evergro Fruit Tree…………………………………………….1037
and Berry Food

Time Release Fertilizer

Green Valley Berry Food…………………………………….2384


Interpreting the Data


There are different ways of measuring radioactivity. These results show the “counts per minute” (CPM) measured with a Geiger counter of radiation detected in each sample. The average for the organic fertilizers was 140, while the “chemical” fertilizers had an average radiation count of 721, a claimed to be five-fold increase by some. This figure is, however, wrong.


Firstly, it is important to note that these tests don’t provide any insight into the type of isotopes being measured and the source of the isotopes. I.e. Geiger counters can detect radioactivity but they cannot tell you which isotope is responsible for it. So, for instance, you’ll note that the organic fertilizers are either extremely low in potassium or possess no potassium at all, while the “chemical” fertilizers typically possess very high levels of potassium. I.e. when combining the total K in the 7 organic fertilizers with known NPK values there is a total of 3.5% v/v K. This equates to 0.5% v/v K average across 7 products. However, when combining the total K found in the 17 “chemical” fertilizers there is 254 % potassium (K = v/v or w/v in the case of one liquid product). This equates to 14.94% on average across 17 products or 29.88 times the K in the “chemical” fertilizers when compared to the organic samples (factoring in fertilizer sample number differences).


This becomes extremely important in interpreting the data. For instance, when measuring the CPM of potassium salt (food grade) at close distance with a Geiger counter, one-teaspoon worth is likely to register around 80-100 CPM.


Therefore, a good deal of the additional CPM registered from the “chemical” fertilizers would be potassium-40 (attributable to the beta and gamma radiation from potassium-40) at levels that wouldn’t pose any risk to people whatsoever. As Dr Cal Herrmann (PhD), head chemist at General Hydroponics, pointed out when discussing the study:


“His table shows values of radioactivity for various fertilizers, which seems to be listed in the same order as the potassium content. The organic fertilizers containing little or no potassium list very low in radiation, and the chemical fertilizers containing naturally radioactive potassium give more of the potassium electron-radiation.”


What he, perhaps, also should have mentioned, given the General Hydroponics Flora Grow reference at 400 CPM, is that much of this reading is likely related to water. I.e. hydrogen (H), which has three naturally occurring isotopes, one of which (tritium) is radioactive, and water has the chemical symbol of H2O. I.e. a water molecule has two hydrogen atoms covalently bonded to a single oxygen atom.


Yet, another factor that is very noticeable (but seems to have been completely overlooked by many) is that the NPK values of the “chemical” fertilizers, in general, are far higher than the NPK values of the organic products. For instance, when evaluating the NPK averages in the organic fertilizers, of the seven products with known NPK values, excluding the unknown NPK DML Bird Guano a total combined average of 11.85 NPK presents, versus 17 “chemical” fertilizers with an average of 46.41 NPK or 3.916 times more NPK than the organic fertilizers.


Given that the research was related to testing the radioactivity of “fertilizers” (i.e. elements such as N, P, and K) this was a significant oversight on the part of the researchers. I.e. it is important to note that when measuring CPM radioactivity of fertilizers, in general, the more the element in question the higher the CPM reading potentially will be. Further, various fertilizers would be expected to emit far higher CPM values of radiation than others. For instance, an N fertilizer with no P and K would emit vastly lower (likely nil above background radiation dependent on type of N) levels of radiation than a fertilizer containing P and K (due to the presence K-40 and rubidium-87 in K and P related isotopes in P). Therefore to compare a 12-0-0 organic fertilizer to a 5-20-20 inorganic fertilizer (40 times the P and K) and state that it emitted 24 times higher than background radiation tells us nothing other than 40 times more radioactive material yielded 24 times the radiation which when applying the authors logic tells us that the “chemical” fertilizer must then be about half as radioactive as the organic fertilizer (of course I’m joking just to demonstrate how numbers, when presented in a certain way, can be deceptive). Just as a quick example, taking a couple of random samples:


RainGrow Organic Fertilizer……………………..160




Greenleaf Shur Gro…………………………………………….672
Soluble Plant Food


Okay, so let’s delete the N from the equation. While we can’t be certain there is nil radiation attributable to the N in both samples either way it would be very low. Besides this, P and K are the elements in question. Additionally, with 20 N in the “chemical” sample and 4 N in the organic sample the results will go in favour of the organic sample if N were a source of radiation. Firstly, while the authors of the study seem to be saying that background radiation was 90 CPM this seems highly unlikely given normal background radiation is stated at between 25-75 CPM. So, let’s be generous and say 75 CPM at the top end of the range. So, 672 (“chemical fertilizer CPM) – 75 (background CPM) = 597 and 160 (organic fertilizer CPM) – 75 = 85.


Then, 597 (CPM chemical sample less background) divided by 85 (CPM organic sample less background) = 7.96 times the radiation from “chemical’ sample. However, we have 10 times more P and 6.666 times more K and yet a radiation reading of only 7.96 times more the value. What this really tells us is that when comparing these two samples (variables factored in) the “chemical” sample is emitting lower radiation than the organic sample. The point being, the research methodology is highly flawed and the findings would fail to pass any scientific peer review muster. I.e. in order to conduct an experiment of this nature and give its findings any credibility, at the very least, we would need to have samples of equal numbers (e.g. 10 organic and 10 “chemical) with equal NPK ratios to compare against each other. Further, this would only tell us what fertilizers emitted what radiation and certainly couldn’t be presented with alarmist information about cancer causing radiation (i.e. polonium-210) without measuring for polonium-210 (the claimed to be deadly isotope in question).


Therefore, while it is extremely difficult to extrapolate accurate data where so many variables are concerned (a point the researchers seem to have missed completely) in order to establish the true difference in radioactivity values between the organic and “chemical” fertilizers the NPK variables would need to be factored in and what we would be left with would be anywhere between a 1.2 – 1.5 and not a 5 fold increase in radioactivity as has been stated. Again though, we actually have no idea of what isotopes we are dealing with, at what CPM.


For instance, I’ve likely been overly generous to the organic fertilizers in not fully accounting for the nitrogen in the inorganic (“chemical”) versus organic fertilizer samples. I.e. soil fertilizers (most of which the inorganic fertilizer samples are) typically use urea, either in full or part,  as the source of nitrogen. Urea (CO(NH2)2) has two NH₂ groups joined by a carbonyl (C=O) functional group.  Basically, for the purposes of this discussion, the urea molecule has four hydrogen atoms and one atom of carbon, all of which emit radioactivity. And all of which have nothing to do with polonium-210.


In short, while this study has been presented as evidence that “chemical” fertilizers contain higher degrees of harmful radioactive isotopes (cancer causing radioactivity no less) the study fails to demonstrate this because not a single one of these isotopes was actually demonstratively shown to be present. That’s not that they aren’t present – they very likely are, at extremely low levels in some samples (both organic and “chemical”?). However, it’s as if the authors are desperately trying to sharpen what can only be described scientifically as a very blunt axe; which is hardly surprising, given that one of the lead researchers, David Malmo-Levine, was nearly a year before the release of this study spreading extremely dubious information about radioactive chemical phosphate fertilizers causing “probably 90% of cancer in smokers.”


This claim, by the way, was somewhat of a distortion of something Jack Herer said in the Emperor Wears No Clothes (page 110) where Herer claims: “Former Surgeon General C. Everett Koop said on national television that radioactivity contained in tobacco leaves is probably responsible for most tobacco-related cancer.”


Jack Herer cites this event as having occurred in 1990 (as does David Malmo-Levine), which is most unusual given Surgeon General C. Everett Koop resigned as Surgeon General on October 1 1989.  Not to be too hard on Jack Herer because, let’s face it, the man is a legend to some, having written a seminal text for generations of stoners, but directly following this he makes another statement that looks extremely questionable. I.e. he then adds: “ No radioactivity exists in cannabis tars.”  This, simply, is not scientifically supported, given that other plants such as potatoes, coffee beans, apples, pears and grapes are all shown to absorb levels of Polonium-210, which is then ingested by humans (most of which – 68-82% – is then eliminated from the body in stool). (Keslev. D, 1973 and others)


Given this, cannabis, as with any other plant, would uptake polonium-210 if present in soils or solution and, much like tobacco, absorb it from other environmental sources (i.e. water and air) meaning that cannabis smokers, as with tobacco smokers, are exposed to levels of polonium-210 that would be found in the smoke stream. Clearly, more research is needed. The point really being that these claims have been mimicked/repeated by many (including Malmo-Levine) and they both appear more than questionable.


Anyway, putting aside what appears to be two highly questionable claims in a single paragraph of a book that some take as gospel, the structure of a study such as this should be hypothesis, test, conclusion and not conclusion, test, and then distort and aggrandize data/conclusion (no matter how flawed) with, at best, scientifically questionable, at worst, spurious and, arguably, defamatory claims.


What is perhaps even more concerning is that so many have taken what is patently flawed information (at best, agrichemical hating hippy dribble) and spewed it across websites as factual information…


To be fair to the authors of the study (Dr Paul Hornby and David Malmo-Levine) they do raise some important points. Firstly, phosphorous rock fertilizers (whether organic or inorganic) may be potentially problematic in soils and hydroponic solutions and because of this their use could be minimized or avoided completely through the incorporation of lower radioactivity value non phosphate rock fertilizers in “chemical” hydroponic nutrient formulations. Secondly, the most important point raised in the study is that this is an area which warrants more research. I.e. do hydroponic nutrients with equivalent NPK values to organic fertilizers possess below, equal or higher radioactivity values? What sorts of isotopes are we talking about, at what levels? And given plant uptake potential, do these isotopes pose any potential health risk to consumers at these given levels?


NPK Total Values of Organic Fertilizers (7 known – one unknown excluded)

N = 39.5

P= 40

K = 3.5

Total NPK = 83


NPK Total Values of Inorganic Fertilizers (17 fertilizers)


N = 243

P = 292

K = 254

Total NPK = 789