Glyphosate and AMPA residues in oversprayed and buffered streams were monitored following application of ROUNDUP (2.0 kg/ha) to 45 ha of a coastal British Columbia watershed. Maximum glyphosate residues (stream water, 162 ju.g/L; sediments, 6.80 ;ug/g dry mass; suspended sediments, <0.03 /ug/L) were observed in two intentionally oversprayed tributaries, dissipating to <1 Mg/L within 96 h postapplication. Buffered streams were characterized by very low glyphosate residue levels (2.4-3.2 /ug/L in stream water). Results of the off-target deposit assessment indicated <0.1% of applied glyphosate at 8 m from the spray boundary. Increases in residue levels were observed in relation to the first storm event postapplication. Ratios of maximum stream water concentrations of glyphosate observed in buffered and oversprayed tributaries relative to literature toxicity values indicated a substantial margin of safety under either operational or worst case scenarios. Glyphosate [jV-(phosphonomethyl)gIycine], marketedunder the trade names ROUNDUP or VISION (Monsanto Corp., St. Louis, MO), has been registered for use in site preparation and conifer release programs in Canada since 1984 (Malik and Vanden Born, 1986). The behavior of glyphosate in aquatic systems has been investigated in the United States and elsewhere (Comes et

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Fusobacterium nucleatum is a ubiquitous member of the human oral flora and is associated with the development of periodontitis and a variety of other types of polymicrobial infections of the mucosa. In the oral cavity, this species is one of the few that is prevalent in both healthy and diseased subgingival plaque. Using microarray analysis, we examined the transcriptional response of F. nucleatum subspecies nucleatum to whole blood in order to identify some of the genetic responses that might occur during the transition from health to disease. From these studies, we identified a sialic acid catabolism operon that was induced by the presence of blood. We subsequently confirmed that this operon was inducible by the presence of synthetic sialic acid, but we found no evidence suggesting sialic acid was used as a major carbon source. However, this organism was found to possess a de novo synthesized surface sialylation ability that is widely conserved among the various F. nucleatum subspecies as well as in F. periodonticum. We provide evidence that fusobacterial sialylation does occur in the oral cavity irrespective of health status. Interestingly, only a minority of fusobacterial cells exhibit surface sialylation within dental plaque, whereas most cells are uniformly sialylated when grown in pure culture. The implications of these results are discussed.

A B S T R A C TOff-target deposit has been quantified from various silvicultural glyphosate application methods and an estimate made of the buffer-zone widths required around water to protect jish and their invertebrate food species fiom possible toxicological effects. To overcome the difjiculty of estimating different buffer widths to meet the various use conditions encountered, a realistic worst-case scenario was chosen for small-drop dr$ and data were collected accordingly.Three glyphosate application methods were tested, employing a helicopter equipped with a 'Microfoil' boom, a 'Thru Valve Boom' and 08-46 hydraulic nozzles respectively. Airborne glyphosate and off-target glyphosate deposits on ground sheets and foliar surfaces were measured at downwind distances between 50 and 200 m fiom multiple overlaid crosswind swaths. Over this distance airborne glyphosate decreased by factors of 3-130, ground deposits by factors of 4-2200, and foliar deposits by factors of 5-100. I n general, airborne glyphosate and off-target deposit was highest fiom the 08-46 application, and lowest from the 'Microfoil' boom application. Using these measurements, mathematical equations were formulated to predict glyphosate deposits on water surfaces downwind of multiple swath applications, and calculations made for 100-ha applications. Large-drop drijit was also calculated using a ballistic model. A n estimate was then made of buffer widths required around water bodies to prevent toxicological effects from small-and large-drop drift, using reported glyphosate toxicities to salmon, rainbow trout and various aquatic invertebrates. A buffer width of 25 m around water bodies limits mortality in populations of salmon, rainbow trout and aquatic invertebrates to less than 10 % for the application methods employing the 'Microfoil' and 'Thru Valve' Boom. For the third application method a 30-m buffer width is suggested.183 Pestic. Sci. 0031-613X/90/$03.60 0 1990 SCI. Printed in Great Britain

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