Glyphosate / published under the joint sponsorship of the United Nations Environment Programme, the International Labour Organisation, and the World Health Organization

Evaluates the risks to human health and the environment posed by glyphosate, a post-emergent, systemic, and non-selective herbicide used, primarily against deep-rooted perennial species, in agriculture and forestry, and for weed-killing in water systems, parks, road verges, and gardens. Roundup is the major formulation of glyphosate. Because of its agricultural uses, concern centres on the possible presence of residues in crops and animal tissues destined for human consumption. Concerning possible presence of residues in crops and edible animal tissues, the report cites evidence that such residues are negligible. The report further concludes that the low toxicity, low volatility, and low body absorption of glyphosate make its application by backpack sprayer safe when workers wear full protective clothing. A review of studies in laboratory animals and in vitro test systems supports the conclusion that glyphosate has very low toxicity when administered by the oral and dermal routes, does not induce sensitization, and shows no mutagenic, carcinogenic, or teratogenic activity. While the formulation Roundup is acutely toxic to humans when ingested intentionally or accidentally, dermal absorption is low, and no adverse effects are expected in properly protected workers. Studies of adverse effects on other organisms in the laboratory and field demonstrate low toxicity for bees, earthworms, and birds. The risk to most aquatic organisms was judged to be small or negligible. While marked changes in populations of birds and small mammals have been documented following glyphosate application, these changes are attributed to alterations in habitat, vegetation cover, and food supply resulting from the herbiide s intended effects

Amitrole / published under the joint sponsorship of the United Nations Environment Programme, the International Labour Organisation, and the World Health Organization

Evaluates the risks to human health and the environment posed by exposure to amitrole, a herbicide with a very wide spectrum of activity against annual and perennial broad leaf and grass type weeds. Amitrole, which appears to act by inhibiting the formation of chlorophyll, is widely used around orchard trees, on fallow land prior to sowing, along roadsides and railway lines, and for weed control in ponds. The herbicide is not approved for direct application to food crops. A review of studies on the environmental fate of amitrole concludes that the compound is relatively rapidly degraded in the environment, with no evidence of either bioaccumulation or entry into the food chain. Exposure of the general public is expected to be minimal. Studies in both humans and animals show that amitrole is rapidly absorbed and rapidly excreted in urine in an unchanged form. The most extensive section evaluates the large number of experimental studies that have demonstrated toxic effects on the thyroid. These findings support the conclusion that amitrole is goitrogenic, causing thyroid hypertrophy and hyperplasia, depletion of colloid, and increased vascularity. Experiments indicate that these changes precede the development of thyroid neoplasia; the precise mechanism triggering the change from hyperplasia to neoplasia remains to be elucidated. Although studies of occupationally-exposed workers are largely reassuring, the book recommends annual monitoring of thyroid function in workers regularly handling amitrole at either the formulation or application stage. The book further concludes that amitrole poses no significant threat to the environment, that levels in food and drinking-water should be extremely low, and that the herbicide poses no threat to the health of workers or the general population when manufactured and used as recommended

Propachlor

Evaluates the risks to human health and the environment posed by propachlor, a re-emergence and early post-emergence herbicide in use since 1965. Derived from acetanilide, propachlor is used in agriculture to control annual grasses and some broad-leaved weeds in several crops, including corn, sorghum, pumpkins, flax and flowers. A section devoted to the environmental behaviour of propachlor cites rapid degradation by microorganisms in soil and water, and concludes that this chemical does not bioconcentrate or biomagnify. Studies of metabolic fate in different mammalian species point to rapid elimination of propachlor and its metabolites. The remaining sections evaluate findings from toxicological investigations in experimental animals and, for humans, the limited data available from cases of contact and allergic dermatitis reported in farmers and production workers exposed to propachlor. For experimental animals, the liver and kidneys are identified as the target organs. For human exposures, the report found no evidence of symptoms or diseases reported for either occupationally exposed workers or the general population, with the exception of scattered reports of dermatitis in workers. On the basis of these evaluations, the report concludes that, under conditions of normal use, exposure of the general population is unlikely. For occupationally exposed workers, the report recommends the use of adequate safety and hygienic precautions to protect the skin, eyes, and respiratory tract. Though propachlor is judged to pose a low hazard to birds, earthworms, and honey-bees, evidence indicates high toxicity to some aquatic organisms, supporting the conclusion that direct contamination of water courses should be avoided