Aromatic Amines An Assessment of the Biological and Environmental Effects (1981) / Chapter Skim
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Trifluralin and Oryzalin
Trifluralin and Oryzalin
Pages 228-273
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From page 228... ...
It has a much lower vapor pressure (less than 10 7 mm Hg at 30°C) than trifluralin, but is slightly more soluble in water (2.5 ppm at 25°C)
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S International Trade Commission listed the Sodyeco Division of Martin Mar ietta Corporation, Sodyeco, N.C., as a producer of oryzalin in 1977 and 1978.
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Oryzalin has been suspected of causing heart-related birth defects among children fathered by workers involved in its manufacture and of causing skin rashes in workers. However, EPA investigations did not disclose any adverse effects, and no regulatory action is planned (Chemical Marketing Reporter, 1980~.
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09 Total 100 0 .45 Stanford Research institute, 1979 231
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Although no data are available on trifluralin plant discharges, small quantities are known to be discharged into the Wabash River as waste from the manufacturing processes. m e treatment procedure involves activated sludge, followed by settling, and then filtration through activated carbon (Specie and Hamelink, 19791.
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At this rate of loss, trifluralin does not tend to accumulate in soils receiving repeated applications. Although the rate of volatilization of trifluralin depends to a great extent on the method of its application, such dissipation provides a signif icant potential exposure route for persons living downwind of treated f ields .
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and vapor losses during spraying to be at 3.58. Exposure of persons living downwind of sprayed fields is somewhat reduced because trifluralin is subject to fairly rapid photochemical decomposition.
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. In treated root crops, such as onions and garlic, trifluralin residues are found only in the outer shell, which is usually discarded before consumption.
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to determine trifluralin residues in soils requires a 4-hour Soxhlet extraction of the oven-dried sample with benzene-isopropyl alcohol (1:2~. The extract is evaporated just to dryness, dissolved in hexane, cleaned on a Florisil column and subsequently analyzed 236
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The procedure permits simultaneous GC assays of trifluralin and diphenamid, without cleanup, by employing a Couison electrolytic conductivity detector. Paraquat is determined calorimetrically.
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The procedure was used to confirm trifluralin residues in extracts of potato spiked at levels of 0.5 to 1.0 ppm. Woodrow et al.
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file MID procedure W8S ma id to have a shorter analysis time and to be lest susceptible to contamination than were EC-GC assays.
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other techniques for determining trace quantities of organic compounds in biologic materials. Residues of the compound were separated from rat tissue and excrete by sequential high-pressure gel permeation and reverse-phase liquid chromatography.
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Review Division, Office of Pesticide Programs (OPP) , and is reported in ~Trifluralin (Treflan} Position Document.
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~: lo E~ o 0 0 E~ v a: P4 a lo P
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Neg! Anderson et al., 1972 Insect Drosophila melanogaster Negt,C Murnik, 1918 Chromosomal Mutations Insect Drosonbila ~nelanogaster pofib,c Murnik, 1978 Other studies Exposed Hu~nans posd Yoder et al., 1973 Neurospora Po~ Gr if f iths, 1979 Sordar ia Bond and McMillan, 1979 Mouse bone marrow Pos Nehez et al., 1979 Part IT: unspecified Trifluralin Gene Mutations Bacterial Salmonella typhimurium!
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c Product sample used contained 177 ppm NDPA. d Chromatid lesions in lymphocytes of workers exposed to herbic ides.
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Trifluralin produced negative results in this study. Simmon _ al.
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In each of these assays, the investigators treated bacterial cultures with a single saturated paper disc containing a 0.02 ml solution of a standard sample made up at a concentration of 1 me trifluralin per milliliter of dimethylsulfoxide. Irifluralin showed negative results for mutagenicity in this study.
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groups. No positive controls were reported, and the formulated trifluralin tested contained approximately 177 ppm NDPA.
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The authors concluded that this preparation induced chromosomal aberrations in bone marrow at total doses of as little as one-third the LD50. Plant Studies.
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Furthermore, Jackson and Stetler did not establish a dose-response relationship, included no positive control in the study, and provided no information on the amount of NDPA that contaminated the study material. Nonetheless, this study does indicate that trifluralin interferes with the formation and function of plant cell microtubules, and the substance, may therefore, disrupt the mitotic spindle, thereby inducing numerical chromosomal aberrations.
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Sentein (1977) reported that trifluralin inhibited mitosis by interfering with the spindle apparatus in two urodele salamanders, Triturus helveticus and Pleurodeles waltl.
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. However, the study does confirm, in an animal test system, the potential antimitotic action of trifluralin previously found in plant cytolog ic studies.
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NDPA Mutacenicitv Data The principal contaminant of technical trifluralin preparations is NDPA, which is a demonstrated oncogen in rodents (Mbntesano and Bartsch, 1976~. NDPA has been studied in In vitro mutagenicity assays with bacteria and yeasts, as well as in mammalian cell culture, coupled with appropriate mammalian metabolic activation 253
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From page 254... ...
When the cofactors for the microsomal mixed-function oxidase were omitted, the mutagenic effect was absent. Positive results for gene mutation as well as for chromosomal aberrations were also obtained in Chinese hamster lung cell cultures treated with 20 mmol NDPA and a rat liver enzyme preparation (Kuroki et al., 1977; Matsuoka et al., 19797.
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Mutagenic Risk Assessment Neither technical nor formulated trifluralin (containing NDPA at levels of up to 177 ppm) has shown any mutagenic activity in the studies cited here.
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From page 256... ...
On the other hand, HDPA by itself has been shown to be mutagenic in several in vitro microbial test systems by causing base-pair substitution and primary DNA damage (Chaisson and Burkhalter, 19781. NDPA concentrations in the trifluralin preparations tested may have been too low to produce gene mutations or direct DNA interaction, especially in the presence of trifluralin {Chaisson and Burkhalter, 1978~.
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From page 257... ...
did not significantly increase the number of mutations in the offspring of treated males {Propping et al., 19721. DMN also produced negative results when male mice were administered DEN at 8 or 9 mg/kg body weight by the same route (Epstein et al., 1972~.
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Only one of three dominant lethal studies with these chemicals in mice suggests a positive effect, and that study reported a very weak positive finding with DMN. However, DEN produced negative results in a specific locus test with mice.
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Because r isks of adverse ef fects are intimately related to exposure and because the expected exposure of humans to NDPA is low, it is also expected that any risk from point mutagenic effects would be minimal. To obtain a better evaluation of point mutagenic risks, other tests should be conducted on NDPA, including studies assessing it'; ability to reach the mammalian gonad in a metabolically active form.
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in Drosophila showed nondisjunction. Replication of these tests with tech n ical tr if rural in having no detectable NDPA produced negative results.
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From page 261... ...
and variations in skeletal development in mice (Beck, 1977 ~ are not evidence of mitotic spindle effects and do not support the theory of a mutagenic effect of trifluralin in mammalian systems. Evaluation of hematologic values from chronic toxicity studies also did not elicit any such evidence (Mauer, 1978~.
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NDPA may induce mutagenic effects, but the expected low exposures to this chemical suggest that the degree of hazard, even if NDPA are a germinal mutagen, are low.
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Schnell Publishing Company, New York. Chemical Marketing Reporter.
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Stanford Research Institute International, Menlo Park, Calif.
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1977. Trifluralin volatilization losses from a soybean field.
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1976. Gas chromatographic separation of herbicides of major interest in Canada, with electrolytic conductivity detection in the nitrogen and chlorine modes.
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1974. A aulti-residue extraction procedure for the gas chromatographic deteraination of the herbicides dichlobenil, dinitramine, triallate and trifluralin in ~oila.
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1977. Postnatal detection of prenatal exposure to herbicides in mice, using normally occurring var.
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Office of Pesticide Programs, Special Pesticide Review Division, Washington, D.C., August 29, 1979. Epste in , S .
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Toxicology Branch, Office of Pesiticide Programs, Enviornmental Protection Agency, Washington, D.C.
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1979. The mutagenic effect of trifluralin~containing herbic ide on mouse bone marrow In viva.
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1972. Comparative investigations on the chemical induction of point mutations and dominant lethal mutations in mice.
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Prepared by Stanford Research Institute, Menlo Park , Calif ., for the Environmental Protection Agency, Health Effects Research Laboratory, Research Triangle Park, N.C. Report No.
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