The toxicological risk of pesticides used in ‘conventional’ crops and those authorized in organic farming is compared for the first time.
The valuable analysis is gathered in the study by Austrian researchers from Friends of Earth (FOE) and the University of Natural Resources and Life Sciences (BOKU) in Vienna. (1)
Pesticides, organic and conventional compared
The researchers compared the toxicity to humans and the aquatic environment of all pesticides authorized in Europe by hazard and risk classifications given in the authorization process according to the international GHS(Global Harmonized System of Classification and Labelling of Chemicals) classification system.
The molecules examined were selected from 450 included in the European Union’s pesticide database. The comparison concerns
- 256 agrotoxics authorized in conventional agriculture, (2)
- 134 pesticides allowed in organic farming. (3)
The (expected) result of the comparison and the limitations
The comparison shows-as expected-that pesticides allowed in conventional (and integrated farming) are much more dangerous than those used in organic. More than half of those substances threaten humans, who are exposed through diet, work and environmental pollution, especially in areas adjacent to crops. And attentive to life in the aquatic environment, so also to human life also through fish consumption.
Before presenting the comparative analysis conducted by the Austrian researchers, a few clarifications are useful:
- The study considers only active substances. The inclusion of co-formulants and the cocktail effect would most likely have a much worse outcome, for pesticides in use in conventional agriculture,
- In organic farming, crop defense by pesticides is a last resort. It affects an average of 5-10% of organic soils. Indeed, the prerogative of this system is to prevent pest attacks and other threats to plants through crop rotation, biodiversity protection and soil health,
- the impact on the environment reported by GHS hazard classes is limited to effects on the aquatic environment, thus toxicity to fish, crustaceans, daphnia (small crustaceans also called water fleas) and algae, as well as degradation and bioaccumulation of substances. It does not, however, address harmful effects on pollinators (including through ‘drift effect‘), birds, earthworms and groundwater.
The nature of pesticides
A first and telling difference between the pesticides allowed in the two agricultural methods lies in the nature of the substances:
- 87.9 percent of the molecules allowed in conventional agriculture (225) are derived from petroleum,
- 100 percent of pesticides allowed in organic are natural substances or substances of natural origin (as required by EU reg. 848/2018), which degrade rapidly. Fifty-six percent are microorganisms, such as bacteria, viruses and fungi.
Super concentrated molecules
The nature and origin of pesticides is not an idle question. It determines, among other things, the mode of action and ‘range’ of the molecules.
Synthetic agrotoxics are now being designed to express increasingly higher lethal ranges and the use of smaller quantities.
The toxicity of herbicides sprayed in Austria to ‘collateral victims’ such as bees, earthworms and birds, for example, increased by more than 400 percent, while their use in terms of agricultural area decreased by 24 percent, the study authors report.
In contrast, substances approved in organic have a soft action and therefore require the use of larger amounts of product, one to three orders of magnitude in comparison with agrotoxics.
The HRI 1 factor, BigChem‘s gimmick.
This quantitative difference is understandable given the different toxicity of the substances. And it makes it improper to assess the risk related to pesticides for conventional and those for organic simply by adding up the amount used.
However, the very arithmetic sum is uncritically adopted with the indicator (HRI 1, Harmonized Risk Indicator 1) used within the European Farm to Fork strategy to monitor expected pesticide reduction targets for 2030. A crass concept that gives the chemical industry a hobbyhorse to accuse organic of spreading too many pesticides.
The adoption of the HRI 1 indicator actually generates a misinterpretation of reality, benefiting the chemical giants. And it is also stigmatized by the European Court of Auditors, as the Austrian environmental organization Global 2000 explains well. (4)
Modes of action compared
Another significant difference between the two categories of pesticides allowed in organic and conventional lies in the mode of action of the substances.
Almost all synthetic pesticides used in conventional agriculture work by inhibition of insect biochemical processes. In contrast, among the substances allowed in organic, this mode characterizes only three insecticides. (5)
In the organic method, in fact, permitted substances act by driving away pests or enhancing plant defenses. Therefore, it is very rare to observe the development of resistance to the substances, which is common among pesticides used in conventional.
Think of vinegar or soap, which act in a physicochemical way, damaging the cell membrane of parasites. To sodium bicarbonate and slaked lime, which alter the ph and dry out the target organism. To vegetable oils that make a physical barrier or garlic that drives pests away with its odor.
Blacklisted agrotoxics
It is not surprising to find that blacklisted pesticides, that is, candidates for substitution because they are very dangerous to humans or the environment, are
- 18.7 percent (48 substances) of those authorized for conventional agriculture, compared with a meager 2.3 percent (6 molecules) of low-risk substances,
- 3.7 percent (5 copper compounds) of pesticides approved for organic, where in contrast the share of low-risk substances is 22.4 percent.
Dietary and non-food exposure limits
EFSA limits for dietary and non-food exposure to pesticides are another significant issue. It concerns 93% of the molecules in use in conventional. In contrast, 93.3 percent of pesticides approved for organic are free of precautionary health protection claims.
The more stringent exposure levels set by EFSA for molecules authorized in conventional are also two orders of magnitude lower than for substances used in organic. In practice,
- in bio, the insecticides spinosad, pyrethrins and azadirachtin, and the fungicide thymol have exposure limits between 0.1 and 0.01 mg/kg body weight,
- in the conventional, 5 synthetic herbicides and two insecticides are subject to much more alarming exposure limits, between 0.001 and 0.0001 mg/kg pc.
Indications of danger
Indications of danger to human health and the environment are also very numerous in pesticides authorized for conventional agriculture (54.7 percent) and rare (3 percent) in those in use in organic, as shown in the summary table we have compiled based on the data that emerged in the Austrian study. (6)
Toxicity to the aquatic environment
Aquatic toxicity (both acute and chronic) concerns only two pesticides authorized in organic, namely the insecticides pyrethrins and spinosad.
Among pesticides used in conventional agriculture, however, severe acute toxicity to the aquatic environment characterizes 39.8 percent of the substances (102 pesticides) and chronic toxicity nearly half of the molecules in use: 49.6 percent, or 127 agrotoxics.
Conclusions
Without chasing venomous shortcuts, the organic method continues to investigate how to reduce the use of pesticides through research on agroecological cultivation and improving plants so that they are more robust and resistant to fungi.
The synthetic chemical agrotoxics used in conventional (and integrated) agriculture, however, are clearly more dangerous and poison two-thirds of the planet. The only way forward-despite BigChem ‘s lobbying-is to pursue the goal of liberating land by converting to organic. As long as the common interest is really to protect human health and the environment as well as food safety.
Marta Strinati
On the cover, graphic elaboration on Fig 2 of the study in note (1).
Notes
(1) Burtscher-Schaden, H.; Durstberger, T.; Zaller, J.G. Toxicological Comparison of Pesticide Active Substances Approved for Conventional vs. Organic Agriculture in Europe. Toxics 2022, 10, 753. https://doi.org/10.3390/toxics10120753
(2) The list does not include the 10 pesticides authorized for post-harvest spreading on conventional agricultural products are (1-methylcyclopropene, 1,4- dimethylnaphthalene, 2-phenylphenol, aluminium sulphate, benzoic acid, carvone, phos- phane, pyrimiphos-methyl, sodium silver thiosulphate, and sulfuryl fluoride).
(3) The list of organic pesticides examined is exclusive of the 47 substances used in traps (pheromones and other semiochemicals, as well as the three insecticides diammonium phosphate DAP, deltamethrin, and lambda-cyhalothrin), the two used in storage gas (CO2 and ethylene), and two other substances authorized only for postharvest treatment (clove oil and mint oil).
(4) HRI 1: a risk indicator to promote toxic pesticides? Global 2000. February 2022 https://www.organicseurope.bio/content/uploads/2022/06/GLOBAL2000_HRI-1_final_28022022.pdf?dd
(5) The three pesticide substances authorized in bio that disrupt insect biochemical processes are two plant secondary compounds (azadirachtin and pyrethrins) and the bacterial agent spinosad. The first substance inhibits hormonal molting of insect larvae, the other two inhibit nerve impulse transmission.
(6) The 4 substances allowed in organic farming that carry hazard statements are the two insecticides spinosad derived from actinobacterium Saccharopolyspora and pyrethrin derived from the plant species Chrysanthemum cinerariifolium, as well as the fungicidal compounds hydrogen peroxide and sulfur.
Pyrethrins are harmful if ingested or inhaled and harmful in contact with the skin. In addition, pyrethrins and spinosad should be labeled as very toxic to aquatic organisms, with long-lasting effects. Elemental sulfur causes skin irritation, while hydrogen peroxide causes severe skin burns and serious eye injury), and is also harmful if ingested or inhaled.
Professional journalist since January 1995, he has worked for newspapers (Il Messaggero, Paese Sera, La Stampa) and periodicals (NumeroUno, Il Salvagente). She is the author of journalistic surveys on food, she has published the book "Reading labels to know what we eat".
