Overview of Glyphosate Toxicity and its Commercial Formulations

What Is Glyphosate?

Glyphosate is an organophosphorus compound used as a herbicide in many countries because it can block the action of plant enzymes and is used to treat weeds and many broad-leaf types of grass that can damage crops. This compound is used by farmers for weed control in agricultural fields, including many genetically modified crops also, and the chemical is absorbed by roots or foliage.

Glyphosate is mainly used during the pre-harvest season to prevent weed growth. Therefore, it produces systemic effects as it cannot be easily washed away from food. In addition, the chemical is also used for domestic purposes like gardening, and at public places, thus producing effects on human health through constant exposure.

What Are the Uses of Glyphosate?

Glyphosate is the major ingredient in commonly used herbicides worldwide named Roundup, Pondmaster, and Rodeo for weed control.

It is mainly used for:

• Vegetables and fruit crops for controlling weed growth.

• Aquatic plants, plantations, greenhouse, and home lawns.

• Many glyphosate-resistant crops (canola, soybean, corn) are also treated.

What Are the Symptoms Produced by Glyphosate Toxicity?

The symptoms of glyphosate toxicity are:

• Headache.

• Dizziness.

• Diarrohea.

• Hypotension.

• Kidney failure.

• Anxiety.

• Weakness.

• Low heart rate.

• Difficulty in breathing.

• Nausea.

• Vomiting.

What Are the Health Effects of Glyphosate Toxicity?

Glyphosate effects are considered similar in animals and humans.

These include:

• Hepatic Effects- An increase in serum markers, liver weight, and hepatocellular necrosis was observed in an animal model.

• Ocular Effects- Glyphosate exposure produces irritation and pain in the eyes with abnormalities in the eye lens.

• Gastrointestinal Effects- Glyphosate ingestion can cause vomiting, nausea, sore throat, damage to the mucosa of the esophagus and abdomen, and abdominal pain. Also, some alterations occur in the salivary glands due to glyphosate exposure.

• Body Weight Effects- Oral glyphosate exposure can decrease body weight due to prolonged chronic exposure.

• Developmental Effects- Glyphosate is usually not associated with any developmental defects but increased or decreased body weight can be caused due to its exposure. In some cases, delayed puberty can occur in males, and many organ system diseases can be seen in both males and females. It can also lead to a decrease in sperm production and fetal skeletal abnormalities.

• Renal Effects- Glyphosate exposure can decrease the urine's pH (potential of hydrogen), increase urine gravity, and also causes hypertrophy of proximal renal tubules.

• Cancer Effects- Glyphosphate exposure can also be associated with lymphohematopoietic cancer, multiple myeloma, or non-Hodgkin’s lymphoma. Exposure to glyphosate chemicals during pregnancy can cause a high risk of cancer in developing fetuses and children.

How Does Glyphosate Affect the Environment?

• Effects on Biodiversity- Glyphosate can cause damage to wildlife biodiversity, mainly near the production site and during product testing on a large scale in wild farmlands. The significant decline in wildlife and biodiversity is often due to glyphosate herbicides and other broad-spectrum insecticides, that are used to kill weed growth.

• Aquatic Toxicity- Glyphosate and its metabolites are highly soluble in water and thus can cause damage to the aquatic environment. It is used to prevent weed growth in aquatic sources and therefore is known to produce more toxic effects on aquatic organisms than in mammals. The phosphate can also be beneficial for some aquatic species like phytoplanktons, while it can be harmful to others as it can cause an increase in algae, affecting aquatic health.

• Terrestrial Toxicity- Glyphosate affects the terrestrial ecosystem, like plants, animals, and birds. It can be found in animal urine, showing increased liver toxicity and muscle cell toxicity symptoms. Accidental ingestion of glyphosate can produce vomiting, diarrhea, weakness, prostration, and hypersalivation in animals.

What Are the Commercial Formulations of Glyphosate?

The commercial formulations of glyphosate mainly contain salts, such as:

• Potassium salts.

• Sodium salts.

• Acids.

• Monoammonium salts.

• Diammonium salts.

• Isoproplyamine salt.

• Trimethylsulfonium salt.

• Trimesium salt.

Glyphosate can be used alone or with herbicides to control weed growth. These glyphosate products are usually formulated as salts, and the major variation between different glyphosate products is the type of salt used in the formulation. Also, the additives or surfactants used in the glyphosate product are another major difference.

The glyphosate chemical is a weak acid with a negative charge, and the salt is formed by adding glyphosate acid to the base with a positive charge. When this product is used on plants, the herbicidal activities are only produced by the glyphosate acid in the plant tissue by binding with the plant enzyme.

Different glyphosate salts can produce different effects because they have different acid-to-salt ratios and molecular weights. The glyphosate salts are absorbed and translocated differently at the target site for weed growth control.

Other components, such as surfactants, adjuvants, and carrier solvents, are also included in glyphosate formulations. These ingredients promote glyphosate products' safety, handling, and solubility and help in the spreading, emulsification, absorption, and penetration of herbicide sprays in plants.

What Is the Risk of Exposure to Glyphosate?

• Glyphosate exposure from home lawns and gardens through breathing or touching can irritate the eyes, nose, throat, and skin. It can also cause corneal injury in the eyes, increased mouth burns, saliva production, diarrhea, nausea, and vomiting. This can be prevented by washing the hands thoroughly after using the product and discarding the clothes worn while handling glyphosate.

• Since glyphosate chemicals are sprayed on crops and fruit orchards, therefore, exposure through food also occurs. In addition, many genetically modified and non-genetically modified crops are treated with glyphosate for early harvesting. Thus, glyphosate enters the food chain, causes exposure, and produces health risks.

How Is Glyphosate Toxicity Managed or Treated?

Glyphosate exposure is not much harmful, but high dose toxicity can produce severe symptoms which can be managed as follows:

• Oxygen support to treat breathing difficulty.

• Intravenous fluids are given.

• Medication is provided to treat the symptoms and effects of poison from glyphosate.

• Urine and blood tests are done.

• Chest X-rays and ECG (electrocardiogram) are also done for proper diagnosis.

Conclusion:

Glyphosate is a widely used herbicide to protect plants from unwanted grasses and weed growth. The herbicide protects the plant during the growth phase up to the fruit ripening period by killing the weed growth. Glyphosate is available in different formulations in the market for different purposes, depending on the salt ingredient they contain. These herbicides of glyphosate formulation are also associated with human health risks that may be caused due to exposure. Glyphosate can be used in domestic and public gardens and vegetation fields to protect plants by controlling weed growth.