What impact of pesticides on health?

France is the fourth largest user of agricultural pesticides in the world and the largest European user. Pesticide sales there reach around 80,000 tonnes a year. More than 300 active substances, contained in more than 3000 commercial preparations, are used in the French agricultural sector. More than 100 active substances, grouped together in more than 500 commercial preparations, are "authorized in the amateur garden .

While pesticides have enabled great progress in controlling the production of food resources and in improving public health, we have noticed since the 1950s that these substances have deleterious effects on the environment and human health. The controversies are lively in scientific and political circles because the links of cause and effect are difficult to establish. Pesticides are, however, suspected of playing a role in the increase in the cases of certain diseases such as cancers, neurological diseases (Alzheimer's disease, Parkinson's disease, etc.), endocrine diseases or even of participating strongly in the reduction of fertility observed over the past 60 years.

The population is in close and daily contact with a multitude of harmful molecules. Food is the main source of exposure to pesticides. Contaminants can also be present in the atmosphere, the professional environment, or in the indoor air of our homes, which concentrates a veritable cocktail of toxic substances.

To protect your health and preserve biodiversity, you should avoid using synthetic pesticides as much as possible and above all protect the most vulnerable populations, such as pregnant women and children. Avoiding spraying insecticide on your houseplants, mulching your flowerbeds to limit weeds, washing fruits and vegetables carefully before eating them are all simple actions that can limit your exposure to phytosanitary products at home or while gardening.

What is a pesticide?

Pesticides are toxic substances used to eliminate organisms considered harmful to agricultural production or public health. There are a multitude of different active substances.

Composed of the Latin words “pestis” which means “scourge” and “caedere” which means “to kill”, the term “pesticide” passed into everyday language in France in the 1950s, a date from which the use of these substances has doubled every decade. The almost systematic use of pesticides in the agricultural sector as in daily life, makes their residues omnipresent in the environment.

A multitude of different molecules

Pesticides are most often obtained by chemical synthesis, but can also have, more rarely, a biological source such as bacteria, for example.

The pesticide product consists of:

• one or more active substances, toxic molecules that act on the harmful element,
• an adjuvant, a chemical substance intended to reinforce the action of the active substances or to facilitate the use of the final product such as solvents, preservatives,
• as well as impurities accidentally integrated during manufacturing.

In France, more than 300 active substances, contained in more than 3000 commercial preparations, are used in the agricultural sector. 80% of pesticides used in agriculture are for cereal crops, corn, rapeseed and vines. More than 100 active substances, grouped together in more than 500 commercial preparations, are "authorized in the amateur garden for individuals.

Pesticides belong to more than 150 chemical families, the main ones being:

• organochlorines, which are very persistent in the environment,
• organophosphates, which are very toxic but have the ability to break down quickly,
• pyrethroids
• and phytosanitary products which are the most used in France.

Various uses

Thanks to their toxic properties, pesticides are used to prevent, control or eliminate organisms considered harmful to agricultural production or to public health such as certain animals, fungi, insects or even plants:

• herbicides kill weeds,
• insecticides kill insects,
• fungicides kill fungi,
• rodenticides are used against rodents,
• molluscicides against snails and slugs,
• acaricides against mites,
• nematicides against worms,
• etc.

Pesticides are also used to control plant growth, improve the storage and transport of agricultural productions.

Pesticides fall under four different regulations:

• plant protection products or plant protection products for farmers, amateur gardeners and maintenance staff of green spaces, urban roads or railways,
• biocidal products used for example by professionals in the wood treatment industry, by public health professionals. and in home use,
• parasiticides for human use to treat scabies or eliminate lice for example,
• antiparasitics for veterinary use.

What are the effects of pesticides on health?

Although the effects of pesticides on health are the subject of intense controversy, they are nevertheless suspected of playing a major role in the appearance of certain cancers, in the increase in certain neurological or endocrine diseases or even of participating strongly in the decline in fertility observed in recent years.

The active substance contained in the pesticide, which targets one or more organisms considered harmful, can also be toxic for living organisms that it does not target.

Controversial health effects

While acute pesticide poisonings are easily identifiable and gain consensus, the health effects following chronic exposure to low doses are the subject of controversy today. These effects are difficult to establish due to several factors:

• due to their very large number and the multiplicity of modes of exposure (inhalation, ingestion, dermal exposure, etc.), it is very difficult to study the effects of each of the active substances over the long term,
• the active substances contained in a product can interact with each other, causing other health effects. Interactions can also take place with adjuvants which may have their own toxicity or increase the effect of the active substance, or with impurities accidentally integrated during the manufacture of the pesticide,
• the population is also in constant contact with a multitude of pesticide residues via food, air... However, this "cocktail effect" has not been studied very much at the moment,
• diseases suspected of being induced by chronic exposure to pesticides, such as cancers, are multifactorial diseases. It is therefore almost impossible to establish an indisputable causal link. Cancers in the agricultural environment can, for example, be caused by greater exposure to the sun, proximity to livestock viruses, etc.

Acute poisoning

Acute poisonings are mainly listed in the professional environment, for example when a farmer is accidentally exposed to fumes from his pesticide tank. The symptoms depend on the product to which people have been exposed but most often are found headaches, burns of the respiratory tract and skin, digestive disorders.

Cancers

The impact of the use of pesticides on the increase in cancer cases has been particularly highlighted with the use of chlordecone in the West Indies during the 70s to 90s. The use of these pesticides has indeed greatly increased cases of prostate cancer.

While some studies show slightly lower cancer mortality among farmers compared to the rest of the population, it appears that certain specific locations are over-represented in this same class of population. For example:

• hematologic cancers,
• hormone-dependent cancers such as prostate, ovarian or breast cancers,
• brain tumours,
• skin cancers,
• lung cancer,
• non-Hodgkin's lymphoma (NHL),
• and soft tissue sarcomas, very rare cancers in the adult population.

An increase in cases of leukemia and brain tumors is suspected in children whose parents use pesticides at home during pregnancy and early childhood. In addition, it seems that the occupational exposure of parents increases the risk of developing cancer for children.

Respiratory conditions

Farmers have a higher risk of developing respiratory conditions such as asthma, compared to the rest of the population.

Endocrine disruption

Pesticides are strongly suspected of causing dysfunction in the hormonal system. For example, the herbicide Round Up, the most sold in the world, is strongly suspected of being an endocrine disruptor and of causing, after exposure of one of the two parents, the doubling of late spontaneous abortions.

Neurological conditions

Pesticides are believed to cause an increase in:

• Parkinsonian syndromes in farmers and people living near plots where pesticides have been applied,
• cases of Alzheimer’s disease,
• disturbances in attention or mood with increased irritability, anxiety and increased incidence of depression,
• a reduction in cognitive abilities as shown by the Phytoner study published in 2012
• Pesticides are also implicated in the rise of Attention Deficit Hyperactivity Disorder (ADHD) in children.

Periconceptional problems

Pesticides are very strongly suspected of playing a major role in the decline in fertility observed in recent years as well as in the increase in in-utero malformations. Scientists find:

• lower sperm count and sperm quality in men,
• a significant increase in cases of infertility in women,
• an increase in low birth weight infants,
• an increase in cases of in-utero genital malformations such as:
• cryptorchidism which is the absence of descent of the testicles in the bursae,
• hypospadias which consists of a bad position of the urinary meatus,
• cases of micropenis,
• but also abnormalities of brain development involving neuropsychological and neurocognitive disorders.

Here again, the population most affected is that of farmers.

Mortality

Finally, exposure to pesticides is correlated with higher mortality 15 years later.

How to protect yourself from pesticides?

The use of synthetic pesticides should be avoided as much as possible and above all the most vulnerable populations such as pregnant women and children should be protected.

Protecting yourself from pesticides at home

Avoid the use of pesticides indoors when you can.

• for example, chemical anti-lice treatments should be avoided. Dangerous for humans, they lead to resistance of the parasites to the insecticide. It is necessary to favor products without insecticides composed of vegetable oil which asphyxiates the lice, in addition to a combing carried out using a comb whose teeth are not separated by more than 0.3 mm. This treatment will be repeated as many times as necessary and completed by careful washing of clothes and linens in contact with the head,
• Avoid gradual release insecticides that are placed next to the bed to repel mosquitoes for example. Prefer essential oils or the installation of mosquito nets,
• do not spray synthetic pesticides on houseplants and favor natural treatments.

Protect yourself from pesticides in food

• eat organic if you can. Otherwise, peel the fruits or vegetables that lend themselves to it and wash the others carefully,
• do not offer water with a nitrate concentration between 50 and 100 mg/l to pregnant women and infants. Do not consume or use for food water with a nitrate concentration equal to or> 100 mg/l,
• respect the water restrictions decided by the authorities in the event of significant pollution. The recommendations are then disseminated to the population by posting in town halls. If the restriction lasts a long time, the town hall may have to provide the inhabitants with drinking water.

You have the possibility of knowing the levels of pollutants present in the water of your municipality by consulting the results of the sanitary control of the quality of drinking water, municipality by municipality, on the website of the Ministry of Social Affairs and Health.