All things considered, there exist no scientific way to make a herbicide risk-free. They are deadly chemicals possessing toxic active ingredients that can impact life forms and the environment by deteriorating health and quality respectively. Countless studies have linked its exposure to various human health issues like cancers, birth defects, neurodegenerative diseases, reproductive issues and hormonal dysfunctions. The indiscriminate use of herbicides can also cause environmental degeneration, contamination of resources and trans-generational implications. Sometimes, it is worrisome that the fallacy that herbicides are safe medicines exists. Not only are herbicides dangerous to plants, but they are also hazardous to animal health, including humans. Many herbicides are considered HHPs or Highly Hazardous pesticides due to their potential to induce detrimental effects to animals and the environment.

“Highly Hazardous Pesticides mean pesticides that are acknowledged to present particularly high levels of acute or chronic hazards to health or environment according to internationally accepted classification systems such as WHO or Global Harmonized System (GHS) or their listing in relevant binding international agreements or conventions. In addition, pesticides that appear to cause severe or irreversible harm to health or the environment under conditions of use in a country may be considered to be and treated as highly hazardous”.

(FAO and WHO in 2013)

How do herbicides enter our body?

People working with herbicides, especially farmers are routinely exposed to the risks posed by these chemicals. In many cases, people choose to ignore PPE (Personal Protective Equipment) because of unpleasant, hot, humid and wet conditions. This can put them in danger as active ingredients in the formulations can enter our bodies and disrupt our health. Not only the ones who are applying them, but the bystanders and residents nearby are also at risk of herbicide exposure.   Routes of exposure can be oral (through ingestion of herbicide-contaminated food or water), inhalation (through breathing contaminated air), dermal (through the skin) and ocular (affecting the eyes). The majority of occupational exposure to herbicides occurs through the dermal and inhalation routes.

Oral exposure: Oral exposure occurs when we consume food with herbicide residues. The ways in which one can be subjected to oral exposure to herbicides are pointed out below.

  • Consumption of food without proper hygiene after herbicide application.
  • Storing herbicide containers in the kitchen or near consumables can lead to exposure of food to herbicides which in turn will enter our body through ingestion.
  • Improper cleaning of crops harvested from herbicide-applied fields that still have herbicide residues can lead to oral exposure and sometimes herbicide poisoning.
  • It can also occur accidentally when a person tries to clear the blocked nozzles of containers.
  • Storing food and water in used herbicide containers can pose severe risks.

Inhalation Exposure: Inhalation exposure occurs when a farmer is exposed to herbicide-contaminated air. This can happen when a farmer uses herbicides containing volatile components and doesn’t use appropriate respirators as instructed on herbicide labels. Spraying equipment can produce inhalable aerosols which can easily enter our respiratory system via inhalation. Inhalation exposure can occur in the following ways.

  • Keeping herbicide containers inside the house can contaminate the air. Especially high-volatile herbicides.
  • Indoor application of herbicides can lead to fogging.
  • Entering into herbicide-treated fields without personal protection.
  • Smelling herbicides and related equipment for checking their quality and hygiene respectively.
  • Bystanders and residents can also be exposed to herbicides via drift.

Dermal Exposure: Dermal exposure occurs when we don’t use gloves at all stages of herbicide use, from preparation for its disposal. Using cotton cloths on farms while applying can lead to the wetting of these clothes by herbicide droplets, contaminating our skin. So, in order to avoid the herbicide spilling into our skin, the entire body should be protected with waterproof and chemical-resistant PPE. The extend of penetrance of a herbicide to a person’s skin varies according to different herbicides.

How herbicides affect our bodies?

Herbicides at high doses of kill you swiftly, and at low doses kill you slowly.

Herbicides possess variable toxicity and are capable of inducing several severe acute and chronic health issues in humans and other animals. Their potent toxic nature can produce the following effects.

Acute Health Issues

The outcome of the extensive and routine use of herbicides in agricultural systems and common setups has been tragic. In India, more than 200 people died following Poisoning by an herbicide named Paraquat in the state, Odisha. Until now, several herbicides have deteriorated the health and claimed the lives of many innocent people across the world. Acute herbicide poisoning and exposure, accidental, malicious and homicidal, has already become a global public health challenge. Major share of these herbicides belongs to HHPs or Highly hazardous pesticides according to PAN (Pesticide Action Network) International list. It is based on internationally accepted classification systems such as WHO or Global Harmonized System and their listing in relevant binding international agreements or conventions. Farmers and farm workers, when disproportionately exposed to herbicides during application are reported to develop fatal diseases and debilitating symptoms. In severe cases of exposure, even death may happen. The major symptoms associated with acute herbicide exposure/poisoning are mentioned below. If you experience any of the symptoms above followed by herbicide, immediately seek professional help.

Chronic Health Issues

The major long-term health issues that can develop in a person when exposed to herbicides frequently are briefed below.

Herbicide and cancer:  Herbicides have been identified to show carcinogenic effects in humans and animals. Among them, farmers are the most vulnerable group to get affected by carcinogenic herbicides due to occupational exposure. Long term occupational exposure to these increases the risk of cancer, including breast and prostate glands among farmers and workers. Some herbicides are grouped as ‘probable carcinogens’ by IARC (The International Agency for Research on Cancer), as they are known to cause several cases of cancer all over the globe.

Herbicides and endocrine system; Some pesticides are capable of disrupting the physiological processes in our body. Some of them can disrupt the function of endocrine glands and can cause hormonal imbalances in humans. They are called endocrine disruptors (ED). They either disrupt the synthesis of hormones by inducing direct toxicity on an endocrine organ or by mimicking the hormones to bind with cognate receptors of the hormone. These herbicides, when they enter our body, can ultimately lead to developmental defects and disrupt reproductive functions in humans which can, in turn, lead to sterility, cancer in the reproductive organs, lowered sperm counts etc.

Herbicides and reproductive system; There are herbicides which have been reported to cause reproductive disorders in humans and are considered human reproductive toxicants by EU or Japan GHS. They are known to cause alterations in gametogenesis, stillbirths and birth defects. They are also able to cause DNA damage, foetal damage, follicular atresia and lesions reproductive organs of mammals.

Herbicides and nervous system; Herbicides are highly capable of causing neurotoxic effects (poisonous to the nervous system) in humans. If not handled carefully, we will be exposed to them and can induce adverse effects in our peripheral and central nervous systems leading to several neurodevelopmental conditions like Parkinson’s disease, Alzheimer’s disease, dementia etc.

Herbicides and immune system;  Herbicides can be a threat to our immune system. They can cause abnormal proliferation of B and T lymphocytes. Lack of immunity can make us highly vulnerable to different kinds of infections and diseases.

Who are affected the most?

Farmers, farm workers and applicators are more susceptible to herbicide exposure. They are the primary sitting targets of herbicide toxicity under deplorable condition of chemical handling. i.e. without PPE (Personal Protective Equipment) during storing, mixing, loading, spraying, disposing and washing pesticide containers or pesticide-soaked clothes. Bystanders and residents who live near agriculture farms also suffer the impacts of herbicide drift. They can indirectly be affected by the herbicides through residues in contaminated air, water as a result of herbicide-drift (movement of herbicides from a site of application).

Women, especially farm workers are more susceptible to exposure. Women comparatively have a high proportion of fat and hormonally sensitive tissues and can produce high chances of bioaccumulation, endocrine disruption and reproductive-linked cancers, especially breast cancers. Pregnant women are high at risk because herbicides may have transplacental (ability to pass through the placenta) and teratogenic (ability to cause malformations in embryo) effects and sometimes can be deadly to both pregnant women and fetus.

Children too are prone to herbicide-related issues they consume more air, water and food per unit of body weight. Hence, they are at risk of developing health problems in herbicide-contaminated environment. Especially, children living with nearby farmlands. Other than this, children can be exposed to herbicides applied in schools, parks and roadsides. Playing with used herbicide containers, keeping used containers at home and ingestion of herbicide-contaminated food and water can also increase the exposure risk.

Want to know about the health effects caused by herbicides being used in India.