Roundup is a safe herbicide with low toxicity
Roundup poses major health hazards
Roundup is marketed as a “safe” herbicide, based on outdated and largely unpublished studies by manufacturers.6 But independent toxicological and epidemiological studies confirm that Roundup and glyphosate pose serious health hazards, as detailed below.
4.1.2. People who eat Roundup Ready crops may be eating toxic residues
The effects on animals and humans of eating increased amounts of glyphosate herbicide residues on such crops have not been properly investigated. On the contrary, regulators have ignored risks and changed safety rules to allow higher levels of glyphosate residues into the food and feed chain.
For example, after the 1996 commercialisation of GM RR soy, EU regulators raised the allowed maximum residue limit (MRL) for glyphosate in imported soy 200-fold, from 0.1 mg/kg to 20 mg/kg.7 The UK government claimed that the move was necessary to accommodate the new farm practice of using glyphosate as a desiccant to “burn down” crops before harvest, making grains or beans easier to gather.8 But it also conveniently coincided with the introduction of RR soy.
Indeed, a 1994 report of the Joint FAO/WHO Meetings on Pesticide Residues (JMPR) indirectly admitted that GM soy was a factor in the need for the higher limit. This JMPR meeting appears to have been the source of the recommendation for the new higher residue limit. In its report, the JMPR recommended the higher limit of 20 mg/kg for soybeans. The JMPR said the change was needed because of a combination of two factors: glyphosate’s use as a desiccant before harvest; and to accommodate “sequential application of glyphosate in the crop”9 – a practice that is only possible with GM RR soy, as it would kill non-GM soy.
In a 1999 press interview, Malcolm Kane, the then recently-retired head of food safety at UK supermarket chain Sainsbury’s, confirmed that the European regulators raised the residue limit to “satisfy the GM companies” and smooth the path for GM soy to enter the food and feed market. Kane added, “One does not need to be an activist or overtly anti-GM to point out that herbicide-resistant crops come at the price of containing significant chemical residues of the active chemical in the commercial weedkiller.”8
This high residue limit is potentially unsafe, based on data from independent studies that EU regulators ignored in setting their claimed safe daily dose.10,11,12 Glyphosate, AMPA, and especially the commercial formulation Roundup have been found to be toxic, in some cases at extremely low levels.13,14,15 Roundup damages and kills human cells at levels below those used in agriculture16 and at residual levels to be expected in food and feed derived from Roundup-treated crops.13 Roundup is a potent endocrine disruptor (disturbs hormone function) at concentrations up to 800 times lower than the highest permitted levels in food and feed.17 So people who eat food products from GM RR crops are eating amounts of these substances that may have toxic effects.
4.1.3. Studies show toxic effects of glyphosate and Roundup
Independent studies on human cells and experimental animals have shown that glyphosate and Roundup have serious toxic effects, in many cases at low levels that could be found in the environment or as residues in food or feed.13,14,15 The added ingredients (adjuvants) in Roundup are themselves toxic and increase the toxicity of glyphosate by enabling it to penetrate human and animal cells more easily.13,18,19 Findings include:
- Glyphosate and Roundup caused malformations in frog and chicken embryos.3
- Roundup caused skeletal malformations in rat foetuses.20
- Industry’s own studies conducted for regulatory purposes as long ago as the 1980s show that glyphosate caused birth defects in rats and rabbits. These effects were seen not only at high, maternally toxic doses, but also at lower doses. Interestingly, these effects were discounted by regulators, who approved glyphosate for use in food production.10
- Roundup caused liver and kidney toxicity in fish at sublethal doses. Effects in the liver included haemorrhage and necrosis (death of cells and living tissue).21
- Roundup caused total cell death in human cells within 24 hours at concentrations far below those used in agriculture and corresponding to levels of residues found in food and feed.13
- Roundup caused death of human cells and programmed cell death at a concentration of 50 parts per million, far below agricultural dilutions.16
- Roundup was a potent endocrine disruptor at levels up to 800 times lower than residue levels allowed in food and feed. It was toxic to human cells and caused DNA damage at doses far below those used in agriculture.17
- Glyphosate was toxic to human placental cells and is an endocrine disruptor in concentrations lower than those found with agricultural use. Roundup adjuvants amplified glyphosate’s toxicity by enabling it to penetrate cells more easily and to bioaccumulate in cells.15
- Glyphosate and Roundup damaged human embryonic and placental cells at concentrations below those used in agriculture, suggesting that they may interfere with human reproduction and embryonic development.14
- Glyphosate’s main metabolite (environmental breakdown product), AMPA, altered cell cycle checkpoints by interfering with the cells’ DNA repair machinery.22,23,19,24 The failure of cell cycle checkpoints is known to lead to genomic instability and cancer in humans
- Glyphosate and AMPA irreversibly damaged DNA, suggesting that they may increase the risk of cancer.25,26
- Glyphosate promoted cancer in the skin of mice.27
- Roundup caused cell and DNA damage to epithelial cells derived from the inside of the mouth and throat, and glyphosate alone caused DNA damage, raising concerns over the safety of inhaling the herbicide, one of the most common ways in which people are exposed. Importantly, both glyphosate and Roundup caused DNA damage at concentrations below those required to induce cell damage, suggesting that the DNA damage was caused directly by glyphosate and Roundup instead of being an indirect result of cell toxicity.28
4.1.4. Epidemiological studies on Roundup show links with serious health problems
Epidemiological studies show a link between Roundup/glyphosate exposure and serious health problems, including:
- DNA damage27
- Premature births and miscarriages28,29
- Birth defects including neural tube defects and anencephaly (absence of a large part of the brain and skull)32,33
- Multiple myeloma, a type of cancer34
- Non-Hodgkin’s lymphoma, a type of cancer35,36,37
- Disruption of neurobehavioral development in children of pesticide applicators – in particular, attention-deficit disorder (ADD) and attention-deficit hyperactivity disorder (ADHD).38
Epidemiological studies cannot prove a cause-and-effect relationship between exposure to a suspect substance and a health effect. However, in the case of glyphosate/Roundup, toxicological studies carried out under controlled laboratory conditions confirm the causal relationship to health problems (see 4.1.3).
4.1.5. People are widely exposed to glyphosate
Glyphosate-based herbicides are widely used outside of the farm environment – for example, by municipal authorities to control weeds on roadsides and in parks and school grounds, as well as by home gardeners. So even when farm use is excluded, people’s exposure to glyphosate is significant. In agricultural areas where GM glyphosate-resistant crops are grown, exposure is likely to increase exponentially.
Study findings on human exposures and body burdens include:
- Glyphosate was detected in between 60 and 100% of air and rain samples taken in the American Midwest during the crop growing season.39 Roundup Ready GM crops are widely planted in this region.
- Glyphosate and its main breakdown product, AMPA, were frequently detected in streams in the American Midwest during the growing season.40
- Glyphosate and its main breakdown product AMPA were washed out of the root zone of clay soils in concentrations that exceeded the acceptable quantities for drinking water (0.1 µg/l), with maximum values of over 5 µg/l.41
- Glyphosate was found circulating in the blood of non-pregnant women, albeit at low levels.42
- Urinary body burdens of glyphosate in farm and non-farm families in Iowa were over 900 parts per billion (0.9 mg per kg of body weight) in 75% of farmers, 67% of wives, and 81% of farmers’ children. Urinary burdens in non-farm children were slightly higher than those in farm children. The authors suggested that this was because of the widespread use of glyphosate in non-farm areas, such as in people’s gardens.43
The placental barrier in mammals is often claimed to protect the unborn foetus from glyphosate exposures. But this claim was shown to be false by a research study modeling human exposures, in which 15% of administered glyphosate crossed the human placental barrier and entered the foetal compartment.44
4.1.6. People are not protected by the current regulations on glyphosate
An analysis of glyphosate’s current approval in the EU and in the US suggests that the “acceptable daily intake” (ADI) level, the level of exposure that is deemed safe for humans over a long period of time, is inaccurate and potentially dangerously high.10
Regulators calculate the ADI on the basis of industry studies submitted to the regulators in support of the chemical’s approval. The figure used to set the ADI is the highest dose at which no adverse effect is found (the No Observed Adverse Effect Level or NOAEL), which is also lower than the lowest dose that has a toxic effect (the Lowest Observed Adverse Effect Level or LOAEL). The ADI is derived by dividing this figure by 100, to allow a safety margin.
The current ADI for glyphosate is 0.3 mg per kg of body weight per day (written as 0.3 mg/kg bw/d).
But this ADI has been shown to be inaccurate by two independent studies on Roundup using an animal (rat) and exposure route (oral feeding) approved by EU and international regulators. The studies found that:
- Roundup was a potent endocrine disruptor and caused disturbances in the reproductive development of rats when the exposure was performed during the puberty period. Adverse effects, including delayed puberty and reduced testosterone production, were found at all dose levels, including the LOAEL of 5 mg/kg bw/d.11
- Glyphosate herbicide caused damage to rats’ liver cells that the researchers said was probably “irreversible” at a dose of just 4.87 mg/kg bw/d.12
These studies did not find a safe or “no effect” level (NOAEL). Even the lowest dose tested produced a toxic effect and no further experiments were done with lower doses to establish the NOAEL. A reasonable estimate of the NOAEL might be 2.5 mg/kg of body weight (though this estimate should, of course, be tested). Then, applying the 100-fold safety factor, the ADI should be 0.025 mg/kg bw/d – 12 times lower than the one currently in force.
Even if only the industry studies are considered, the current ADI should still be lower. An objective analysis of these studies results in a more objectively accurate ADI of 0.1 mg/kg bw/d, one-third of the current ADI.10
4.1.7. Arguments that Roundup replaces more toxic herbicides are false
GM proponents often argue that Roundup has replaced more toxic herbicides and that GM RR crops therefore reduce the toxic burden on humans and the environment. But this is false. GM RR crops have not only increased the use of glyphosate herbicides but have also increased the use of other, potentially even more toxic herbicides, due to the spread of glyphosate-resistant weeds (see Section 5). And as we have seen, the presumed safety of Roundup owes more to clever marketing than to objective scientific findings.