>>So how toxic is glyphosate exactly? To examine toxicity, one must look at the LD50 value given to the chemical in question. LD50 is a standard measure of acute toxicity for chemicals, expressed in the amount of chemical (milligrams) per body weight (kg) that it took to kill fifty percent of a population of test animals. Because LD50 is a standard measure, it is used to compare toxicities of compounds; the lower the number, the more toxic it is. Glyphosate has a LD50 of 5600 mg/kg based on oral ingestions in rats, according to EPA assessments (PDF), placing it in Toxicity Category III. The EPA ranks chemicals in four categories, I being the most toxic and IV being the least. The EPA has also found that glyphosate does not cause cancer. To compare, caffeine has a much lower LD50 of 192 mg/kg based on oral ingestions in rats. Caffeine is over ten times more toxic than glyphosate. Is this cause for concern? Should we stop drinking coffee? No, the main reason being that a typical dosage of caffeine is not high enough to cause toxicity. Let’s look at the numbers. With LD50 of 192 mg/kg, it would take 12192 mg of caffeine to kill an average 140 lb human being. A typical 8 oz cup of coffee only contains 95 mg of caffeine, much lower than the dose required for acute toxicity. The same reasoning applies to glyphosate. Following the same calculations, it would take 12.5 oz of glyphosate to kill an average 140 lb human being. That means drinking about three gallons of Roundup Original. But what about long-term exposures to glyphosate? Given its widespread use, there is a good chance that we are eating some residues in our food. The EPA considered this too by setting maximum safe levels of residues called tolerances. The USDA tests crops each year to make sure that herbicide residues do not exceed tolerance levels. If any crops contain residue amounts higher than tolerance levels, the USDA reports the information to the FDA, who has the regulatory power to recall foods, levy fines and take other actions to prevent the foods from reaching consumers. The EPA also made sure that the tolerances were conservative: EPA conducted a dietary risk assessment for glyphosate based on a worst-case risk scenario, that is, assuming that 100 percent of all possible commodities/acreage were treated, and assuming that tolerance-level residues remained in/on all treated commodities. The Agency concluded that the chronic dietary risk posed by glyphosate food uses is minimal. A reference dose (RfD), or estimate of daily exposure that would not cause adverse effects throughout a lifetime, of 2 mg/kg/day has been proposed for glyphosate, based on the developmental toxicity studies described above. Which means that a 140 lb human being can be exposed to as much as 127 mg of glyphosate per day for a lifetime without adverse effects, according to EPA standards. To put this in perspective, the daily upper limit for vitamin D supplements is 4000 IU per day, or 0.1 mg. The EPA’s efforts to ensure that glyphosate is used at safe levels did not put the matter to rest. In an attempt to get out their message that glyphosate is dangerous, anti-GMO activist scientists have turned to pay-for-play journals to publish work that would never be accepted in mainstream science journals, like the two studies by Samsel, Seneff and Séralini. However, uncritical media coverage of these type of studies has lent credibility to them and the anti-GMO activist groups.
Posted on: Tue, 14 Oct 2014 04:31:21 +0000
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