24 April, 2011
Glyphosate, known by its International Union of Pure and Applied Chemistry (IUPAC) name phosphonomethylamino or acetic acid, is manufactured for use as a herbicide. Depending on specific purpose, it may be used as such, or as an ammonium salt, isopropylamine salt, or potassium salt.
It is most well-known as the main active ingredient in the chemical company’s Monsanto's "Roundup." But since the Monsanto patent has expired, it is also used in similar formulations by a number of manufacturers. It works as a plant hormone inhibitor, by interfering with this metabolic process in plants, it kills the plants.
In handling glyphosate, it is essential to have an up-to-date Material Safety Data Sheet (MSDS), which can be obtained from a company that manufactures products with it in it. It is also essential to minimise exposure through engineering controls, isolation, effective ventilation, and where worker exposure is unavoidable, personal protective equipment.
There are two stories on glyphosate, one by its original manufacturer, Monsanto, and unfortunately accepted by most regulatory agencies worldwide, the other by opponents of glyphosate use, who claim much information about it has been suppressed.
As Monsanto tells it, glyphosate is generally considered to be one of the safest herbicides. There is a fairly well-established potential for temporary skin and eye irritation, and gastrointestinal irritation if ingested. These can even be severe if the chemical is encountered in its pure form and not promptly washed off the skin. A survey of recent MSDSs reveals that it is officially considered practically non-toxic, and, in several animal studies, has produced no officially recognized evidence of carcinogenicity, mutagenicity, or teratogenicity.
However, MSDSs are often less than complete. There are some rather alarming suggestions of a link between glyphosate exposure and non-Hodgkin's lymphoma (NHL) by some researchers. Monsanto's claim that there is no severe adverse effect has been traced back to Swedish researcher Hans-Olov Adami, who in turn has been linked to a consulting group called Exponent.
Exponent has ties to Monsanto and other chemical companies and is known for its rebuttals of concerns about chemicals in the environment. Findings about glyphosate that contradict Monsanto have rarely been given much attention.
There are suggestions that it may be an endocrine disruptor or a genotoxin. For example, Gilles-Eric Séralini, a French biochemist, has claimed that his studies of the effects of glyphosate on human embryonic cells, fetal cells, and placental cells; and that glyphosate is likely an endocrine disruptor in humans. This effect was shown for “Roundup” formulations, rather than pure glyphosate. Indeed, one of the issues with any chemical testing is how it will affect humans or the environment in the complex mixture of chemicals encountered in the real world, as compared with its study in isolation in a laboratory.
The statistical significance of the association between glyphosate and NHL is low. Monsanto's defenders have suggested that errors in the assessment of exposure levels, or chance, are the likely explanations for the association between glyphosate exposure and NHL. As for Séralini's observations, it is unclear whether the effects Séralini observed were due to the glyphosate, or the surfactants (detergents) that are always part of a pesticide formulation.
Regardless, from a pure occupational health point of view, the best way to handle any chemical is with caution. Minimise the opportunities for worker exposure with the best possible engineering designs that isolate the chemical from human contact. Install effective drainage and ventilation systems to safely remove any chemical that escapes from the closed system. Finally, since despite these precautions some chance of exposure may remain, appropriate personal protective equipment must be provided and maintained.
The safest level of exposure is always no exposure.