Agrochemicals

Growing demand for higher crop yields resulted in agriculture intensification. While agricultural land area has grown since 1950 by 11 %, the production has risen by 145 %1 – mainly thanks to pesticides and new fertilizers. They allow our population not to starve, however it has been a lot said about their negative impact to the environment.2

Pesticide consumption

in million tonnes

Fig. 1: According to FAO3 the global consumption of pesticides rose in 1990–2010. This increase is mainly due to intensification in Asia and S. America. Europe and N. America (not shown) have not increased (nor decrease) their consumption of pesticides since 1990. FAO estimates the global pesticides consumption was 4,1 million tons in 2018. Out of it, 1,8 million tons were used in China.

There are three main adverse effects of agrochemicals

Environment Pollution

Human Health Impairment

Lovered Fitness of the Crop Itself

Environment

Agrochemicals enter the natural environment through 4 main routes:

1

Spray Drift

Loss during application

2

Evaporation

Loss into the atmosphere

3

Runoff

Flushing of the agrochemicals with rain

4

Leaching

Mobility through soil into ground water

Soil

According to EC report 65-75 % of agricultural soil suffer with at least one of these problems leading to soil degradation:

A

Loss of Organic Carbon

B

Nutrient Abundance

C

Erosion

D

Compaction

E

Salinization

F

Chemical Pollution

G

Desertification

H

Loss of Biodiversity4

Pesticides can be quickly transported into water bodies, but they can also persists in soils for years depending on the precipitation.5 Pesticides overuse negatively impacts soil microbiome – loss of bacteria and fungi leads to fast degradation of soil. Low organic carbon corresponds with poor water retention and impaired chemicals degradation. Fertilizers overuse is the cause of high nitrogen levels in soil and surrounding water bodies, where eutrophication is an issue.4

Water

Eutrophication of streams and lakes is the main adverse effect of fertilizers runoff. Water bloom damages the balance of water ecosystem and causes loss of biodiversity.6 Chemicals entering ground water can contaminate drinking water.2

Air

2–50 % sprayed agrochemicals drift into the atmosphere just during the application.2, 7 Many volatile compounds evaporate into the air even after application. These chemicals are transmitted by the atmosphere over long distances. 62 % of all soil in Europe (not only agricultural) contain high levels of nitrogen due to transport through the air.4, 8

Biodiversity

Intensive agriculture contributes to both biodiversity loss9 as much as decrease of total number of beneficial organisms. 80% reduction of total insect biomass in 27 years has been reported.10, 11 The economic value of pollinators is estimated being 165 billion USD every year.9 Not only that we don’t pay them salary, but pesticides make life much harder for these workers.12, 13 Herbicides decrease biodiversity of plants. The loss of biodiversity is also caused by fertilizers-driven eutrophication.9, 14 It is crucial to realize that the healthy ecosystem performs many services – rich biodiversity brings benefits for agriculture, fishery and forestry.

Health Risk

It is estimated that 200-300 thousand people die of pesticides exposure every year. However, complete global data is missing. Pesticides very often interfere with human nervous system15, 16 and cause inflammation.2 The most endangered are the workers – especially in developing countries, where education and personal protection equipment are insufficient.1, 2, 17, 18 Moreover, everyone is exposed to residues of agrochemicals in food, drinking water, and air.2, 19

Health problems of farmers

Fig. 2: Health issues after occupational exposure to pesticides (data collected in 2016-2018).20

Adverse effects on crop yields

Phytotoxicity

All agrochemicals are to some extent toxic also to the crops they should protect. If the plant is under stress (high temperatures, drought, etc.), it is more sensitive also to pesticide burn. This problem is relevant especially in areas with low education and information accessibility about the pesticides, where these chemicals are often misused18.

Resistance

Resistance in this case indicates reduced effectiveness of pesticides after repeated application. Pesticides select the population of pests – only the strongest ones survive the treatment. If these strong individuals reproduce, the next generation more probably survives application of the same pesticides. Lower effect of pesticides forces farmers to increase doses of chemicals, which can harm natural predators and further decrease pest management opportunities.

Soil microbiome and biodiversity

Both growth and function of fungi and bacteria are impaired when pesticides overused. Low activity of soil microorganisms negatively affects growth and stress resistance of crops2, 21 and must be compensated by higher dose of inorganic fertilizers.

How can PHAs fight with chemical pollution in agriculture? Find out more about controlled-release systems

References

1 Pretty, J. and Z. P. Bharucha. Integrated Pest Management for Sustainable Intensification of Agriculture in Asia and Africa. Insects. 2015, 6(1). doi: 10.3390/insects6010152.

2 Dhananjayan, V., S. Jayakumar and B. Ravichandran. Conventional Methods of Pesticide Application in Agricultural Field and Fate of the Pesticides in the Environment and Human Health. In: R. K. R, Thomas, S., Volova, T. and K, J. Controlled Release of Pesticides for Sustainable Agriculture. Cham: Springer International Publishing, 2020: 1-39. 978-3-030-23396-9.

3 FAO, 2020. FAOSTAT, Pesticides Use. [cit. 15.1., 2021.] Dostupné z: http://www.fao.org/faostat/en/?#data/RP.

4 Commission), D.-G. f. R. a. I. E., C. Veerman, T. Pinto Correia, et al., 2020. Caring for Soil is Caring for Life. https://op.europa.eu/en/publication-detail/-/publication/4ebd2586-fc85-11ea-b44f-01aa75ed71a1

5 Vryzas, Z. Pesticide fate in soil-sediment-water environment in relation to contamination preventing actions. Current Opinion in Environmental Science & Health. 2018, 4: 5-9. doi: https://doi.org/10.1016/j.coesh.2018.03.001.

6 Lürling, M. and M. Mucci. Mitigating eutrophication nuisance: in-lake measures are becoming inevitable in eutrophic waters in the Netherlands. Hydrobiologia. 2020. doi: 10.1007/s10750-020-04297-9.

7 Zhao, X., H. Cui, Y. Wang, et al. Development Strategies and Prospects of Nano-based Smart Pesticide Formulation. Journal of Agricultural and Food Chemistry. 2018, 66(26): 6504-6512. doi: 10.1021/acs.jafc.7b02004.

8 Koolen, C. D. and G. Rothenberg. Air Pollution in Europe. ChemSusChem. 2019, 12(1): 164-172. doi: https://doi.org/10.1002/cssc.201802292.

9 Dudley, N. and S. Alexander. Agriculture and biodiversity: a review. Biodiversity. 2017, 18(2-3): 45-49. doi: 10.1080/14888386.2017.1351892.

10 Crall, J. D., C. M. Switzer, R. L. Oppenheimer, et al. Neonicotinoid exposure disrupts bumblebee nest behavior, social networks, and thermoregulation. Science. 2018, 362(6415): 683. doi: 10.1126/science.aat1598.

11 Hallmann, C. A., M. Sorg, E. Jongejans, et al. More than 75 percent decline over 27 years in total flying insect biomass in protected areas. PloS one. 2017, 12(10): e0185809-e0185809. doi: 10.1371/journal.pone.0185809.

12 Beketov, M. A., B. J. Kefford, R. B. Schäfer and M. Liess. Pesticides reduce regional biodiversity of stream invertebrates. Proceedings of the National Academy of Sciences of the United States of America. 2013, 110(27): 11039-11043. doi: 10.1073/pnas.1305618110.

13 Ewald, J. A., C. J. Wheatley, N. J. Aebischer, et al. Influences of extreme weather, climate and pesticide use on invertebrates in cereal fields over 42 years. Glob Chang Biol. 2015, 21(11): 3931-50. doi: 10.1111/gcb.13026.

14 Glibert, P. M. Eutrophication, harmful algae and biodiversity — Challenging paradigms in a world of complex nutrient changes. Marine Pollution Bulletin. 2017, 124(2): 591-606. doi: https://doi.org/10.1016/j.marpolbul.2017.04.027.

15 Richardson, J. R., V. Fitsanakis, R. H. S. Westerink and A. G. Kanthasamy. Neurotoxicity of pesticides. Acta neuropathologica. 2019, 138(3): 343-362. doi: 10.1007/s00401-019-02033-9.

16 Aloizou, A. M., V. Siokas, C. Vogiatzi, et al. Pesticides, cognitive functions and dementia: A review. Toxicol Lett. 2020, 326: 31-51. doi: 10.1016/j.toxlet.2020.03.005.

17 van den Berg, H., B. Gu, B. Grenier, et al. Pesticide lifecycle management in agriculture and public health: Where are the gaps? Science of The Total Environment. 2020, 742: 140598. doi: https://doi.org/10.1016/j.scitotenv.2020.140598.

18 Bhandari, G. An Overview of Agrochemicals and Their Effects on Environment in Nepal. Applied Ecology and Environmental Sciences. 2014, 2: 66-73. doi: 10.12691/aees-2-2-5.

19 Gillezeau, C., M. van Gerwen, R. M. Shaffer, et al. The evidence of human exposure to glyphosate: a review. Environ Health. 2019, 18(1): 2. doi: 10.1186/s12940-018-0435-5.

20 Dhananjayan, V. and B. Ravichandran. Occupational health risk of farmers exposed to pesticides in agricultural activities. Current Opinion in Environmental Science & Health. 2018, 4: 31-37. doi: https://doi.org/10.1016/j.coesh.2018.07.005.

21 Meena, R. S., S. Kumar, R. Datta, et al. Impact of agrochemicals on soil microbiota and management: A review. Land. 2020, 9(2): 34. doi