Roundup (herbicide)

Composition

Glyphosate-based formulations may contain a number of adjuvants, the identities of which may be proprietary. Surfactants are used in herbicide formulations as wetting agents, to maximize coverage and aid penetration of the herbicide(s) through plant leaves. As agricultural spray adjuvants, surfactants may be pre-mixed into commercial formulations or they may be purchased separately and mixed on-site.

Polyethoxylated tallow amine (POEA) is a surfactant used in the original Roundup formulation and was commonly used in 2015. Different versions of Roundup have included different percentages of POEA. A 1997 US government report said that Roundup is 15% POEA while Roundup Pro is 14.5%. Since POEA is more toxic to fish and amphibians than glyphosate alone, POEA is not allowed in aquatic formulations.

Non-glyphosate formulations of Roundup are typically used for lawns that glyphosate would otherwise kill. Both type of products being sold under the Roundup brand name can be a source of confusion for consumers. Active ingredients for non-glyphosate formulations of Roundup can include MCPA, quinclorac, dicamba, and sulfentrazone, penoxsulam, and 2,4-D

Acute toxicity

The lethal dose of different glyphosate-based formulations varies, especially with respect to the surfactants used. Formulations intended for terrestrial use that include the surfactant POEA can be more toxic than other formulations for aquatic species. Due to the variety in available formulations, including five different glyphosate salts and different combinations of inert ingredients, it is difficult to determine how much surfactants contribute to the overall toxicity of each formulation. Independent scientific reviews and regulatory agencies have repeatedly concluded that glyphosate-based herbicides do not lead to a significant risk for human or environmental health when the product label is properly followed.

Human

The acute oral toxicity for mammals is low, The surfactants in glyphosate formulations can increase the relative acute toxicity of the formulation. Surfactants generally do not, however, cause synergistic effects (as opposed to additive effects) that increase the acute toxicity of glyphosate within a formulation. It is unclear whether the surfactant POEA increases or reduces the overall toxicity of glyphosate-based formulations. Deliberate ingestion of Roundup ranging from 85 to 200 ml (of 41% solution) has resulted in death within hours of ingestion, although it has also been ingested in quantities as large as 500 ml with only mild or moderate symptoms. Consumption of over 85 ml of concentrated product is likely to cause serious symptoms in adults, including burns due to corrosive effects as well as kidney and liver damage. More severe cases lead to "respiratory distress, impaired consciousness, pulmonary edema, infiltration on chest X-ray, shock, arrhythmias, kidney failure requiring haemodialysis, metabolic acidosis, and hyperkalaemia" and death is often preceded by bradycardia and ventricular arrhythmias.

Skin exposure can cause irritation, and photocontact dermatitis has been occasionally reported. Severe skin burns are very rare. In a 2017 risk assessment, the European Chemicals Agency (ECHA) wrote: "There is very limited information on skin irritation in humans. Where skin irritation has been reported, it is unclear whether it is related to glyphosate or co-formulants in glyphosate-containing herbicide formulations." The ECHA concluded that available human data was insufficient to support classification for skin corrosion or irritation.

Inhalation is a minor route of exposure, but spray mist may cause oral or nasal discomfort, an unpleasant taste in the mouth, or tingling and irritation in the throat. Eye exposure may lead to mild conjunctivitis. Superficial corneal injury is possible if irrigation is delayed or inadequate.

Aquatic

Glyphosate formulations with POEA, such as Roundup, are not approved for aquatic use due to aquatic organism toxicity. Due to the presence of POEA, glyphosate formulations only allowed for terrestrial use are more toxic for amphibians and fish than glyphosate alone. Terrestrial glyphosate formulations that include the surfactants POEA and MON 0818 (75% POEA) may have negative impacts on various aquatic organisms like protozoa, mussels, crustaceans, frogs and fish.

Studies in a variety of amphibians have shown the toxicity of products containing POEA to amphibian larvae. These effects include interference with gill morphology and mortality from either the loss of osmotic stability or asphyxiation. At sub-lethal concentrations, exposure to POEA or glyphosate/POEA formulations have been associated with delayed development, accelerated development, reduced size at metamorphosis, developmental malformations of the tail, mouth, eye and head, histological indications of intersex and symptoms of oxidative stress. Glyphosate-based formulations can cause oxidative stress in bullfrog tadpoles. The use of glyphosate-based pesticides are not considered the major cause of amphibian decline, the bulk of which occurred prior to widespread use of glyphosate or in pristine tropical areas with minimal glyphosate exposure.

A 2000 review of the toxicological data on Roundup concluded that "for terrestrial uses of Roundup minimal acute and chronic risk was predicted for potentially exposed nontarget organisms". It also concluded that there were some risks to aquatic organisms exposed to Roundup in shallow water.

Bees

Roundup Ready‐To‐Use, Roundup No Glyphosate, and Roundup ProActive have all been found to cause significant mortality in bumblebees when sprayed directly on them. It has been hypothesized that this is due to surfactants in the formulations blocking the tracheal system of the bees.

Carcinogenicity

There is limited evidence that human cancer risk might increase as a result of occupational exposure to large amounts of glyphosate, such as agricultural work, but no good evidence of such a risk from home use, such as in domestic gardening. The consensus among national pesticide regulatory agencies and scientific organizations is that labeled uses of glyphosate have demonstrated no evidence of human carcinogenicity.{{cite journal

One international scientific organization, the International Agency for Research on Cancer (IARC), classified glyphosate in Group 2A, "probably carcinogenic to humans" in 2015.

Legal

In the ten months following Bayer's June 2018 acquisition of Monsanto, its stock lost 46% of its value because of investor apprehension concerning the 11,200 lawsuits filed against its subsidiary. As of 2023, around 165,000 claims have been made against Bayer, mostly alleging that Roundup had caused cancer. Bayer has settled tens of thousands of those claims and has agreed to pay billions in damages, but, as of 2023, more than 50,000 similar claims were still pending. In December 2023, Bayer won a case against a claim that Roundup had caused a man's cancer. In a statement they said the outcome was "consistent with the evidence in this case that Roundup does not cause cancer and is not responsible for the plaintiff's illness". At that time, Bayer had previously won 10 of 15 such cases.

Most cases claiming injury from Roundup are based on a failure-to-warn theory of liability, meaning Monsanto is liable for a plaintiff's injury because it failed to warn the plaintiff that Roundup can cause cancer. The United States Court of Appeals for the Ninth Circuit in 2021, and the United States Court of Appeals for the Eleventh Circuit in early 2024, held that such state-law failure to warn claims were not preempted by the Federal Insecticide, Fungicide, and Rodenticide Act ("FIFRA"). In August 2024, however, the United States Court of Appeals for the Third Circuit held that FIFRA does preempt state-law failure to warn claims involving Roundup, expressly recognizing that its holding conflicts with that of the Ninth and Eleventh Circuits. This conflict among the Third, Ninth, and Eleventh Circuit creates a heightened potential that the United States Supreme Court will review the Third Circuit's decision so that the Supreme Court can resolve the conflict among the Courts of Appeals.

Cancer cases

As of October 30, 2019, there were more than 42,000 plaintiffs who said that glyphosate herbicides caused their cancer.{{cite news

On August 10, 2018, Dewayne Johnson, who has non-Hodgkin's lymphoma, was awarded $289 million in damages (later cut to $78 million on appeal{{cite news |access-date=July 29, 2019}} then reduced to $21 million after another appeal{{cite news |access-date=March 3, 2021 |publisher=San Francisco Chronicle

In January 2019, Costco decided to stop carrying Roundup or other glyphosate-based herbicides. The decision was reportedly influenced in part by the public court cases.{{Cite web

In March 2019, a man was awarded $80 million (later cut to $26 million on appeal) in a lawsuit claiming Roundup was a substantial factor in his cancer.{{cite news | title = Jury Awards $80 Million In Damages In Roundup Weed Killer Cancer Trial |first=Richard |last=Gonzales |date=March 29, 2019 |publisher=NPR

On May 13, 2019, a jury in California ordered Bayer to pay a couple $2 billion in damages (later cut to $87 million on appeal{{cite news |access-date=July 27, 2019}}) after finding that the company had failed to adequately inform consumers of the possible carcinogenicity of Roundup.{{Cite news |access-date=December 1, 2021 |website=Westlaw Today |agency=Reuters Legal |date=September 18, 2020}}

In June 2020, Bayer agreed to settle more than a hundred thousand Roundup lawsuits, agreeing to pay $8.8 to $9.6 billion to settle those claims, and $1.5 billion for any future claims. The settlement does not include three cases that have already gone to jury trials and are being appealed. However the settlement was not allowed to cover future cases.

In the 2020s, facing billions of dollars in more claims, Bayer lobbied the U.S. Congress and state legislatures to change legal standards for pesticide labeling in an attempt to reduce its liability. , the US EPA planned to reevaluate regulations in 2026.

In May 2025, Bayer announced that it was making another push to settle the pending lawsuits and that it would consider a Chapter 11 bankruptcy for its Monsanto division if the settlement plan was not successful. The company engaged law firms Latham & Watkins and AlixPartners to review its options.

False advertising

In 1996, Monsanto was accused of false and misleading advertising of glyphosate products, prompting a lawsuit by the New York State attorney general. Monsanto had made claims that its spray-on glyphosate based herbicides, including Roundup, were safer than table salt and "practically non-toxic" to mammals, birds, and fish, "environmentally friendly", and "biodegradable".{{cite news |title=Monsanto Agrees to Modify Roundup Ads in New York State

Environmental and consumer rights campaigners brought a case in France in 2001 accusing Monsanto of presenting Roundup as "biodegradable" and claiming that it "left the soil clean" after use; glyphosate, Roundup's main ingredient, was classed by the European Union as "dangerous for the environment" and "toxic for aquatic organisms". In January 2007, Monsanto was convicted of false advertising and fined 15,000 euros. The result was confirmed in 2009.

On 27 March 2020 Bayer settled claims in a proposed class action alleging that it falsely advertised that the active ingredient in Roundup Weed & Grass Killer only affects plants with a $39.5 million deal that included changing the labels on its products.

In June 2023, Bayer reached a $6.9 million settlement agreement with the New York attorney general, settling false advertising allegations concerning the safety of Roundup.

Ban in France

In January 2019, Roundup Pro 360 was banned in France following a Lyon court ruling that regulator ANSES had not given due weight to safety concerns when they approved the product in March 2017. The ban went into effect immediately. The court's decision cited research by the IARC, based in Lyon.{{cite news

Use with genetically modified crops

Main article: Roundup Ready

Monsanto first developed Roundup in the 1970s. End-users initially used it in a similar way to paraquat and diquat – as a non-selective herbicide. Application of glyphosate-based herbicides to row crops resulted in problems with crop damage and kept them from being widely used for this purpose. In the United States, use of Roundup experienced rapid growth following the commercial introduction of a glyphosate-resistant soybean in 1996. "Roundup Ready" became Monsanto's trademark for its patented line of crop seeds that are resistant to Roundup. Between 1990 and 1996 sales of Roundup increased around 20% per year. the product was used in over 160 countries. | access-date = 2018-08-13 | archive-url = https://web.archive.org/web/20180813111122/https://news.nationalgeographic.com/2015/04/150422-glyphosate-roundup-herbicide-weeds/ | archive-date = 2018-08-13 | url-status = dead Roundup is used most heavily on corn, soy, and cotton crops that have been genetically modified to withstand the chemical, but glyphosate treated approximately 5 million acres in California for crops like almond, peach, cantaloupe, onion, cherry, sweet corn, and citrus, | archive-url = https://web.archive.org/web/20180813111122/https://news.nationalgeographic.com/2015/04/150422-glyphosate-roundup-herbicide-weeds/ | archive-date = 2018-08-13 | url-status = dead | access-date = 13 July 2020 although the product is only applied directly to certain varieties of sweet corn.

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