The use of chemical pesticides: the game between benefits and harm, after reading "Silent Spring"!

Author: Yuan Shankui, Pesticide Inspection Institute, Ministry of Agriculture and Rural Affairs.
Chemical pesticides are like a "baby with congenital defects from birth".
As a kind of biologically active chemical substances that humans actively invest in the ecological environment, they will inevitably affect the ecology.
The environment or human and animal health cause more or less negative impacts
.
In 1962, Rachel Carson published the book "Silent Spring", which for the first time in the world took chemical pesticides and environmental protection as themes.
He is not only a literary work, but also a book that has undergone extensive investigation and research.
The masterpiece of popular science, which was completed later, has aroused global awareness and attention to the environmental pollution of pesticide use
.
Today, when "ecological protection" and "green development" have become the theme of the times, I will study this book again.
The views on the safe use and development of pesticides are not outdated, and it is worth thinking about and learning from
.
The book has been published for nearly 60 years.
Pesticides are still being used all over the world, and the sad scenes described in the book have not appeared.
This fully proves a natural law "Intensive agricultural planting is inseparable from the use of pesticides.
The use of pesticides is The game between benefits and harm” also shows that mankind has won the battle to seek benefits and avoid harms of pesticides
.
We cannot blindly "demonize" the harmful effects of pesticides, but should scientifically look at the benefits of pesticide use to mankind, as well as the progress and changes in the continuous development of the safety of pesticides, and maximize our strengths and avoid weaknesses
.
01 Scientific understanding of the advantages and disadvantages of pesticides Pesticides are widely used in the prevention and control of crop pests all over the world, ensuring the improvement of yield and quality, and playing a huge role in meeting the global food demand
.
However, pesticides are often regarded as the "culprit" of food safety and environmental pollution and have been pushed to the "top of the storm" time and time again, lacking scientific, objective and fair evaluation and treatment
.
Knutson and others described the American society without pesticides, "agricultural production will decrease, food prices will rise, competitiveness in the global market will decrease, and agricultural exports will decline, leading to a large number of unemployment.
"
.
1.
1 The harm of pesticides Pesticides are toxic substances released into the environment to eliminate harmful organisms (such as plant diseases, pests, weeds, and rodents).
They can be applied to the environment by spraying, soil treatment, seed treatment, etc.
, of which only a small part Really used (reaching the target), the rest may pollute the farmland and cause harm to beneficial insects, soil microorganisms, etc.
, and then may enter surface water bodies, volatilize into the atmosphere, or act on non-target organisms through ingestion, etc.
, to kill Beneficial organisms such as bees, natural enemies, insects, and frogs can also accumulate among organisms at different levels of the food chain, causing long-term chronic toxicity
.
In addition, pesticides entering drinking water or food can also harm human health and cause a variety of cancers and diseases, especially children, whose immune system, nervous system and detoxification mechanism are not yet fully developed and will suffer greater damage
.
According to literature reports, paraquat can cause damage to human lung, liver and kidney tissues; ethylene thiourea (ETU), a metabolite of dithiocarbamates, can induce thyroid cancer and regulate thyroid hormones; organochlorine pesticides such as DDT ( DDT, also known as bis-p-chlorophenyl trichloroethane) is related to cancer, asthma, diabetes, and childhood growth disorders, as well as endocrine disrupting effects
.
1.
2 The benefits of pesticides The purpose of using pesticides for humans is the benefits they bring to humans, otherwise they will not be used at the expense of the environment and health
.
Pesticides are the most important plant protection technology.
Without these technologies, food production will decline, many fruits and vegetables will be in short supply, and prices will rise; they can be used to control termites, cockroaches, ants, rats and other pests.
People create a good living environment; it can be used to protect public environments such as gardens, parks, sports grounds, lakes and ponds; it can be used to control vector insects and the spread of diseases, such as malaria; it can be used to control plant pathogens or Non-pathogenic microorganisms reduce the pollution of microbial toxins, such as the highly carcinogenic aflatoxin, which is far more harmful than the pesticide itself
.
Therefore, pesticides are tools for humans to fight against nature and bring many benefits to humans.

.
Advertisement 02 Pesticides are evolving along with the times.
Pesticides are constantly evolving with the advancement of science and technology, but they are not a recent "invention.
" As early as 2500 BC, the Sumarians began to use sulfur to control pests and mites.
In 1200 BC, China used mercury and arsenic compounds to control body lice.
Pyrethrum chrysanthemum extract was used as an insecticide for more than 2,000 years.
Salt or sea water was used to control weeds
.
Inorganic substances, such as sodium chlorate and sulfuric acid, or organic chemicals obtained from natural sources, were widely used for pest control before the 1940s
.
The development of pesticides can be roughly divided into five stages: (1) 1000 years ago, the early stage; (2) 1000-1850, using plant, animal and mineral sources; (3) 1850-1940, using inorganic substances and industrial By-products; (4) From 1940 to 1970, use organic synthetic compounds represented by DDT; (5) From 1970 to present, use organic synthetic low-risk compounds
.
Among them, the pesticides before 1940 are also called "first-generation pesticides".
The typical feature is the use of natural-derived compounds such as plants and minerals as pesticides.
Most of them are highly toxic, low in control efficiency, easy to accumulate in the soil, and used for a long time.
There have been resistance problems, and most of them have been eliminated.
The pesticides developed during the period from 1940 to 1970 are called "second-generation pesticides", mainly because the advent of DDT opened the history of chemical synthesis of pesticides.
, Organophosphorus, carbamate pesticides, etc.
The typical features are good control effect, high toxicity to mammals and beneficial organisms, and some species have a long retention period in the environment; in order to overcome the problem of "second generation" high toxicity, After 1970, juvenile hormones, ecdysone, insect pheromone, chitin synthesis inhibitors and other pesticides with low direct toxicity to humans and animals have been developed.
Most of the varieties are environmentally friendly (some varieties are more toxic to environmentally beneficial organisms) ), sometimes referred to as "third-generation pesticides" or even "fourth-generation pesticides"
.
Objectively speaking, these pesticides cannot completely replace the "second-generation pesticides" due to factors such as effect, cost, and residual period.
What has truly become the mainstream of the current pesticides is the high-efficiency, high-selectivity, low-residue, and low-risk "modern chemical synthesis".
Pesticides, such as pyrethroids, neonicotines, bisamides and other insecticides, triazoles, methoxyacrylates, succinate dehydrogenase inhibitors (SDHI) and other fungicides, sulfonylureas, Herbicides such as hydroxyphenylpyruvate dioxidase (HPPD)
.
Therefore, pesticides have been developing in the direction of low toxicity and high efficiency.
"Modern pesticides" are no longer the era of "organochlorine pesticides" with long residues and high bioaccumulation in the 1950s
.
03 Pesticide ecological environment safety management In the 1940s, especially during World War II, due to the need to increase food production and find potential chemical weapons, chemically synthesized pesticides such as DDT, aldrin, dieldrin, endrin Chemicals, 2,4-D, and parathion are used in large quantities, and their application in agriculture is also considered to be beneficial.
At the beginning, there was no concern that these chemicals would have an impact on the environment and human health
.
In 1962, the book "Silent Spring" attracted widespread attention to the safety of pesticides.
Due to the emergence of pest resistance in the 1970s, a large amount of evidence of the negative effects of pesticides was accumulated, and the use of DDT was finally banned in the United States in 1972
.
At the same time, it also prompted the United States to establish the United States Environmental Protection Agency (US EPA) in 1970, which was managed by a dedicated department for the production and use of pesticides.
At that time, it was the world's first government agency specializing in pesticide management, with the main purpose of enhancing the safety of pesticides.
In the 1980s, a technical system for pesticide environmental risk assessment was established, providing a reference for pesticide management in other countries
.
With the approval of the State Council in 1978, China restored the original pesticide inspection institute of the Ministry of Agriculture and Forestry and established a special pesticide management agency
.
After the formal promulgation of the "Regulations on Pesticide Registration" and the implementation of the pesticide registration system in 1982, although the environmental safety of pesticides attracted attention in the early stage, due to the limitations of technical capabilities, talent team and hardware conditions at that time, the focus of pesticide registration was mainly on quality and Effect
.
Compared with developed countries such as Europe and the United States, my country's pesticide environmental safety management is at least 30 years behind, and its development process can be roughly divided into three stages (Table 1)
.
At present, China's pesticide environmental safety management has achieved overtaking on a curve.
From the early subjective judgment based on acute toxicity data, it has entered the stage of scientific quantitative risk management, and has received widespread attention in the world
.
Table 1 China's Pesticide Environmental Safety Management Development Stage 04 Reducing the Harmful Use of Chemical Pesticides Pesticides are an inevitable product of science, technology and social development.
They are extremely important means of agricultural production and are directly related to the development of the national economy, people’s health, and agricultural production safety.
Social stability
.
But as long as we use pesticides in production, it is difficult to avoid their harm.
The most effective way is to minimize the scope and level of their harm
.
"Silent Spring" brings us a lot of enlightenment for our work.
Humans can take many measures to reduce the use of pesticides and reduce the harm of pesticides
.
4.
1 Elimination of high-toxic and high-risk pesticide varieties "Silent Spring" describes the harm to wildlife, fish, birds and livestock caused by the large-scale use of DDT, aldrin, dieldrin and other long-residue and high-risk pesticides in the United States
.
DDT is currently banned in at least 86 countries in the world.
In 1983, the State Council issued a document to stop the production of 666 and DDT pesticides.
In 1992, the former Ministry of Chemical Industry issued a document to stop the use of these pesticides in agriculture, and in 2002 the former Ministry of Agriculture Announcement No.
199 The pesticides are listed in the domestic banned pesticides
.
So far, China has banned and restricted 66 types of pesticides used on crops such as fruit and vegetable tea (approximately 8.
7% of the total pesticide varieties), especially fipronil, carbofuran, flubendiamide, etc.
, which are beneficial to the environment.
The use of more biologically toxic species is restricted, so that the phenomenon like "silent spring" has only appeared in a small area or within a short period of time in our country.
Fish and birds have begun to increase in farmland, and biodiversity is gradually increasing.
Resume
.
4.
2 Strengthen the management of pesticide use to reduce the risk of harm The harm to the environment of pesticides is mostly caused by unreasonable use
.
The scenes from the 1950s to 1960s in the United States described in "Silent Spring", it is not difficult to see that a large number of planes spraying pesticides is an important reason for the impact on non-target organisms.
The problem of pesticide drift is relatively large in China.
At present, this kind of manned aircraft is still used in forestry and agricultural reclamation areas, especially some pesticides used in forestry are highly toxic to bees or birds, such as imidacloprid, abamectin, emamectin benzyl UAV flying defense is experiencing explosive growth, with the annual pesticide application area reaching hundreds of millions of mu
.
The environmental pollution caused by pesticides should arouse great attention
.
Choosing safe and environmentally friendly formulations is also a means to reduce the risk of pesticide use.
In 2019, nano-pesticides became the top ten emerging technologies in the chemical field recognized by IUPAC.
However, the environmental safety of nano-pesticides is also a trade-off in terms of increasing risks and reducing dosage.
Worthy of attention
.
In addition, in actual production, the phenomenon of over-range and over-dose use is also common.
If the abuse of pesticides is not controlled, our scientific evaluation data and materials will become a pile of waste paper
.
4.
3 Strengthening technical guidance and training on the safe use of pesticides Carson does not advocate the absolute ban on the use of chemical pesticides, but firmly opposes letting people who have no knowledge of the toxicity of pesticides use it, and the labels of pesticides are related to toxicity, use and safety precautions, etc.
The font size of the relevant content is very small, coupled with the habit of pesticide users who pay less attention to labels, and the problem of rural aging, which affects the guiding significance and role of pesticide labels in the actual medication process
.
It is necessary to reduce the unreasonable use of pesticides by strengthening training on safe drug use, developing specialized unified prevention and control, and improving the quality of pesticide operators
.
4.
4 Speeding up the use of biological pesticides instead of chemical pesticides.
At that time, Carson summarized the use of radiation technology to sterilize pests, sound wave control, use natural source pesticides, use bacteria to control insects, use insects to control insects and other methods to reduce and replace the use of chemical pesticides.
But after more than 60 years of development, it now seems that these technologies are advancing slowly
.
Investigating the reasons, the driving force of economic interests and the technical bottleneck difficult to break through the biological pesticides are the main reasons.
Government intervention and support are necessary to reverse the disadvantages of biological control methods.
In the future, the development of products, the opening of green channels for registration, and the use of Support in subsidies, tax relief, etc.

.
05 Existing problems and prospects 5.
1 Existing problems Carson consulted a large number of documents, conducted a large number of investigations and studies, and conducted in-depth exchanges with well-known experts from many countries, and pointed out the loopholes or merits in pesticide environmental safety management.
In-depth consideration
.
In light of China's actual conditions, there are still some problems in pesticide safety management that are worthy of our consideration and efforts to solve
.
5.
1.
1 The problem of pesticide compound pollution.
Carson pointed out that our safety evaluation test is to allow our experimental animals to be exposed to a certain pesticide to observe the toxic effects, but in real life, we cannot know that we are at different times.
, How many kinds of pesticides have been exposed to on different occasions, whether it is human and animal health or environmental health, the issue of the "cocktail effect" of pesticides has always been a difficult problem to solve
.
Fortunately, the pesticides we are currently approved for registration will no longer have the strong bioaccumulation like DDT, and we are also establishing and paying attention to environmental risk assessment procedures and methods for pesticide mixtures
.
In addition, there are countless compounds in nature.
Whether pesticides will react with other compounds in nature to produce more toxic compounds, it is difficult to get an accurate answer.
The best way is to avoid and reduce the use of pesticides.
Exposure and contact
.
5.
1.
2 Risk assessment on the perception of pesticide toxicity is the most effective tool for us to predict or evaluate the risk of pesticides under the existing cognition and technical system
.
It allows us to have a uniform standard, which is convenient for us to select pesticide varieties with relatively good activity and relatively low safety risk under the same conditions
.
But objectively, we cannot guarantee that the pesticides with lower risks assessed are necessarily safe, because the accuracy of the assessment cannot be separated from the data on biological effects.
Although we have established relatively complete ecotoxicological test methods, Most of them are macroscopic and acute toxic effects, while microscopic and chronic toxic effects are limited
.
But we must also believe that with the development of molecular biology, metabolomics and other technologies, our awareness of the toxicity of pesticides will continue to increase.

.
5.
1.
3 How to solve the problem of "old accounts" Before China implements strict pesticide environmental risk assessment and safety management measures, some pesticides and use methods that have an impact on the ecological environment have been approved.
In the case of meeting the needs of agricultural production, these Pharmaceuticals and methods of use need to be gradually replaced and cancelled to reduce the impact of pesticide use on the ecological environment to a greater extent
.
5.
2 Prospects There are 739 kinds of common agricultural pests, 775 kinds of diseases, 109 kinds of weeds, and 42 kinds of rodents in China.
Therefore, agricultural production is inseparable from pesticides
.
The introduction of Spodoptera frugiperda from abroad in 2019 and the invasion of Yunnan by the yellow spine locust in 2020 are all through chemical pesticides to effectively control the pests
.
Mankind must continue to develop and produce efficient, safe and environmentally friendly pesticides to meet the growing population's demand for food, but the harm of pesticides to the ecological environment is constantly gaining in-depth understanding and broad consensus
.
The newly revised "Regulations on Pesticide Management" in 2017 raised the threshold of pesticide registration safety management, highlighted the concept of green development, and is leading the development of China's pesticide industry structure in a high-quality direction
.
The direction of pesticide creation and research and development has always been: (1) Pursue high efficiency to achieve the lowest usage; (2) Easy to degrade and reduce residues in the environment; (3) High selectivity to reduce damage to non-targets
.
In the early days, the dosage of pesticides, for example, in the 1930s to 1950s, the dosage of pesticides was 1-10 kg/hm2, while the dosage of many new compounds is now 10 g/hm2 or lower.
Pesticides have made significant progress in the pursuit of high efficiency.

.
In addition, due to the increasing cost of chemical pesticide R&D and the decreasing probability of screening effective compounds, pesticide R&D is moving in the direction of biological pesticides, genetically modified pest-resistant technology, disease-resistant breeding, RNAi technology, and non-biological technology.
, Some multinational companies and large domestic enterprises have begun to join the biopesticide research and development team, and green prevention and control technologies will play a larger and broader role in integrated agricultural pest control (IPM) measures
.