Inhibitor Report for: Bensulide

The TurfPQ model was used to simulate the runoff of 15 pesticides commonly applied to creeping bentgrass (Agrostis stolonifera L.) fairways and greens on golf courses in the northeastern USA. Simulations produced 100-yr daily records of water runoff, pesticide runoff, and pesticide concentration in runoff for three locations: Boston, MA, Philadelphia, PA, and Rochester, NY. Results were summarized as annual and monthly means and annual maximum daily loads (AMDLs) corresponding to 10- and 20-yr return periods. Mean annual pesticide runoff loads did not exceed 3% of annual applications for any pesticide or site, and most losses were substantially less than 1% of application. However, annual or monthly mean concentrations of chlorothalonil, iprodione, and PCNB in fairway runoff often exceeded concentrations that result in 50% mortality of the affected species (LC50) for aquatic organisms. Concentrations of azoxystrobin, bensulide, cyfluthrin, and trichlorfon in extreme (1 in 10 yr or 1 in 20 yr) events often approached or exceeded LC50 levels. Concentrations of halofenozide, mancozeb, MCPP, oxadiazon, propiconazole, thiophanate-methyl, triadimefon, and trinexapac-ethyl were well below LC50 levels, and turf runoff of these chemicals does not appear to be hazardous to aquatic life in surface waters.

Six Beagle dogs were orally intubated with mixtures of a urea-based fertilizer, 2,4-D, mecoprop (MCPP), dicamba, and either bensulide or chlorpyrifos. The mixtures were formulated as they are used in liquid application to lawns. The dogs were given volumes of 10 ml/kg of body weight, delivering the following quantities of each ingredient: urea--623 mg/kg, inorganic phosphorus (P2O5)--24 mg/kg, potassium (K2O)--66 mg/kg, 2,4-D--6.5 mg/kg, MCPP--3.26 mg/kg, dicamba--0.55 mg/kg, and either bensulide--60.93 mg/kg or chlorpyrifos--6.77 mg/kg. The dogs were given 3 consecutive daily doses of the mixture containing bensulide (round 1) or the mixture containing chlorpyrifos (round 2). The dogs did not exhibit any clinical signs of illness associated with the treatments. Effects on hematologic values or routine clinical chemical analyses did not occur with the round 2 mixture. Serum lactic dehydrogenase activity decreased by approximately 50% after a single dose of the round 1 mixture was given. Plasma cholinesterase decreased to approximately 50% of control values following either the round 1 or the round 2 mixture; this decrease was not accompanied by cholinergic signs of intoxication.

Ten organophosphate (OP) pesticides: phorate, disulfoton, terbufos, methidathion, bensulide, chlorethoxyfos, phosmet, methyl parathion, phostebupirim, and temephos were evaluated for their potential to undergo oxidation to their respective oxons and/or other oxidation analogues in laboratory water. Samples were collected at time intervals up to 72h of chlorination and analyzed by both gas chromatography-mass selective detection (GC-MSD) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results show that methidathion and methyl parathion were stable in unchlorinated water, while all other OP pesticides were not stable over the 72h exposure period. In chlorinated water, phorate and disulfoton formed stable sulfone oxons. Temephos formed stable dioxon sulfoxide and dioxon sulfone. Methidathion, bensulide, chlorethyoxyfos, methyl parathion, and phostebupirim formed stable oxons over the 72h exposure period. Terbufos, phorate, disulfoton and temephos oxon sulfoxides; temephos sulfoxide; and phosmet oxon were initially formed but were not detected after 24h. The data illustrate that organothiophosphate pesticides may form oxons and/or other oxidation analogues during chlorination in water treatment plants, which are persistent for at least 72h.

The TurfPQ model was used to simulate the runoff of 15 pesticides commonly applied to creeping bentgrass (Agrostis stolonifera L.) fairways and greens on golf courses in the northeastern USA. Simulations produced 100-yr daily records of water runoff, pesticide runoff, and pesticide concentration in runoff for three locations: Boston, MA, Philadelphia, PA, and Rochester, NY. Results were summarized as annual and monthly means and annual maximum daily loads (AMDLs) corresponding to 10- and 20-yr return periods. Mean annual pesticide runoff loads did not exceed 3% of annual applications for any pesticide or site, and most losses were substantially less than 1% of application. However, annual or monthly mean concentrations of chlorothalonil, iprodione, and PCNB in fairway runoff often exceeded concentrations that result in 50% mortality of the affected species (LC50) for aquatic organisms. Concentrations of azoxystrobin, bensulide, cyfluthrin, and trichlorfon in extreme (1 in 10 yr or 1 in 20 yr) events often approached or exceeded LC50 levels. Concentrations of halofenozide, mancozeb, MCPP, oxadiazon, propiconazole, thiophanate-methyl, triadimefon, and trinexapac-ethyl were well below LC50 levels, and turf runoff of these chemicals does not appear to be hazardous to aquatic life in surface waters.

Six Beagle dogs were orally intubated with mixtures of a urea-based fertilizer, 2,4-D, mecoprop (MCPP), dicamba, and either bensulide or chlorpyrifos. The mixtures were formulated as they are used in liquid application to lawns. The dogs were given volumes of 10 ml/kg of body weight, delivering the following quantities of each ingredient: urea--623 mg/kg, inorganic phosphorus (P2O5)--24 mg/kg, potassium (K2O)--66 mg/kg, 2,4-D--6.5 mg/kg, MCPP--3.26 mg/kg, dicamba--0.55 mg/kg, and either bensulide--60.93 mg/kg or chlorpyrifos--6.77 mg/kg. The dogs were given 3 consecutive daily doses of the mixture containing bensulide (round 1) or the mixture containing chlorpyrifos (round 2). The dogs did not exhibit any clinical signs of illness associated with the treatments. Effects on hematologic values or routine clinical chemical analyses did not occur with the round 2 mixture. Serum lactic dehydrogenase activity decreased by approximately 50% after a single dose of the round 1 mixture was given. Plasma cholinesterase decreased to approximately 50% of control values following either the round 1 or the round 2 mixture; this decrease was not accompanied by cholinergic signs of intoxication.

We studied the activity of 14 compounds, all of which have been shown to interfere in plant cell division, in two animal tumor cell cultures, EL-4 and L1210. Four compounds [propham, chlorpropham, bensulide S-(O,O-diisopropylphosphorodithioate) ester of N-(2-mercaptoethyl)benzenesulfonamide), and siduron] had a 50% inhibitory dose less than 10(-4) M; six [2,3,5-triiodobenzoic acid, (2,4-dichlorophenoxy)acetic acid, bromacil, (2,4,5-trichlorophenoxy)acetic acid, naptalam, and (4-chloro-2-methylphenoxy)acetic acid] had a 50% inhibitory dose between 10(-4) and 10(-3) M, and the remaining four 2,3:4,6-di-O-isopropylidene-2-keto-L-gulonate, eptam, maleic hydrazide, and 4-(methylsulfonyl)-2,6-dinitro-N,N,-dipropylaniline] had a 50% inhibitory dose at higher than 10(-3) M. There was a significant correlation between the effect on the two cell lines as well as between the inhibition of cell proliferation and that of thymidine and leucine uptake. More detailed study of cell proliferation and leucine and thymidine uptake for bensulide and 2,3,5-triiodobenzoic acid revealed a dose-response pattern of inhibition starting shortly after exposure of the cells to the compounds. These results indicate that some inhibitors of plant cell division are capable of inhibiting the proliferation of animal tumor cells.

A scan of the acute toxicities of eighteen common herbicides to one-year-old channel catfish (Ictalurus punctatus) was conducted. Herbicides causing less than 10% mortality in 48 hr at 10 ppm were: alanap, chloramben, 2,4-D acid, 2,4-D dimethyl amine salt, dalapon, diuron, DSMA, EPTC, fluometuron, metribuzin, monuron, MSMA, nitralin and 2,4,5,-T. The 96-hr LC50 values in pp6 for four nerbicides found toxic were: propanil, 3796; trifluralin, 417; bensulide, 379; and DNBP 118. The toxicity of Dyanap, a mixture of DNBP and alanap, was lower than that of DNBP; there was no apparent synergism between DNBP and alanap in the mixture.