George W. Ware

Nitrate and Nitrite

Nitrate and nitrite have a variety of commercial uses. The major use of nitrate is in inorganic fertilizers. It is also used in the manufacture of explosives, in glassmaking, and as a heat-transfer fluid and a heat-storage medium for solar heating applications. Both nitrate and nitrite are used in curing meats. The properties of potassium nitrate and nitrite, two commonly used compounds, are shown in Table 1 (USEPA 1985). Potassium nitrate is also known as saltpeter (Windholz 1976).

Interaction of pesticides with aquatic microorganisms and plankton

The interactions of pesticides 1 and soil microorganisms are heavily documented from the agricultural view. Many of the same soil particles, microorganisms, and pesticides are found in freshwater and estuarine ecosystems, and similar relationships may exist. It is the purpose of this paper, then, to review the interactions of pesticides and aquatic microorganisms, those microscopic plants and animals found in freshwater, estuarine, and marine environments.

Effects of pesticides on nontarget organisms

Pesticide effects on nontarget organisms have been a source of worldwide contention and concern for more than a decade and are the basis for most legislation aimed at controlling or prohibiting the use of specific pesticides. For example, the present list of pesticides to undergo Rebuttal Presumption Against Registration (RPAR) numbers 45. All of these are being reviewed because of their effects on nontarget organisms, most with reference to man. Only 13 were triggered by criteria relating to reduction in nontargets and endangered species (birds and feral mammals) while the rest hinged on laboratory animal effects listed as oncogenicity, fetotoxicity, mutagenicity, teratogenicity, and reproductive effects. Thus, most pesticides undergoing RPAR have untoward effects on laboratory animals that are translated as potential effects on man, the ultimate nontarget.

Establishment of reentry intervals for organophosphate-treated cotton fields based on human data: I. Ethyl-and methyl parathion

In each of two studies, two human volunteers entered methyl- or methyl-ethyl parathion-treated cotton fields for 30-minute periods at 0, 12, 24, 48, and 72 hours after treatment; foliage residues, and skin, clothing, inhalation, and biomedical data were obtained. The hands are probably the greatest source of absorbed pesticide chemical while the respiratory system is an insignificant source. Trousers collect the largest amounts of residue but the residue on them does not necessarily undergo absorption by the skin. There is not any evidence of plasma- or red-cell cholinesterase depression or a detectable amount ofpara-nitrophenol, following one-day, single, 30-min exposure. It is estimated that an individual can absorb up to 6.0 milligrams of parathion from cotton 24 hours after treatment with parathion and up to 3.0 milligrams 48 hours after such treatment, during an actual 5-hour work day field exposure. Skin-, and clothing contamination data are inadequate bases for evaluating hazard of possible parathion poisoning. Far more useful are measurements of serum parathion, serum-, and cell cholinesterase activities, and urinary excretion ofpara-nitrophenol in exposed individuals.

EEC Water Quality Objectives for Chemicals Dangerous to Aquatic Environments (List 1)

Council directive 76/464/EEC of the European Communities (EEC 1976a) is concerned with pollution by certain dangerous substances being discharged into the aquatic environment from point sources, either direct or indirect, e.g., via sewage works. Originally, it did not intend to deal with diffuse sources of pollution, such as contamination of surface waters arising from run-off agricultural land, rain, dry deposition, etc. However, such sources may be taken into account as background information, and they may also be included by member states when using the quality objectives approach.

Methyl Ethyl Ketone

Methyl ethyl ketone is also known as 2-butanone, butan-2-one, ethyl methyl ketone, and MEK. It is used as a solvent in processes involving gums, resins, cellulose acetate, and cellulose nitrate. It is also used extensively in the synthetic rubber industry; in production of paraffin wax and high-grade lubricating oil; and in household products such as surface-coating compounds (lacquer and varnishes), paint remover, and glues. Its structure and properties are in Table 1.

Effects of DDT on reproduction in higher animals

DDT, though used almost exclusively as an insecticide, is toxic in varying degrees to practically all animal life at some dosage and has even been accused of inhibiting photosynthesis in lower plants. Occasionally its toxicity in the environment has been observed in the form of reproductive failure, direct and indirect, and almost exclusively in birds and fish.

Establishment of reentry intervals for organophosphate-treated cotton fields based on human data: III. 12 To 72 hours post-treatment exposure to monocrotophos, ethyl- and methyl parathion.

Five human volunteers entered methyl parathion, ethyl parathion, or monocrotophos treated cotton fields for five-hr exposure periods when the residues of the respective pesticides had aged 12 hr, 24 and 48 hr, and 48 and 72 hr. Foliage residues of methyl parathion disappeared fastest, those of monocrotophos slowest. Personal exposure to pesticide was evaluated from contamination of skin, clothing, and ambient air, while actual absorption of chemical was assessed from pesticide concentration in blood, urinary metabolite excretion, and effects on blood cholinesterase activities. There was good correspondence between magnitudes of foliar residue, estimates of personal contamination, and measures of chemical absorption. Field exposures caused no symptoms or clinical signs of organophosphate poisoning and depressed averaged blood cholinesterase activities by no more than 14% of pre-exposure levels.

ortho-, meta-, and para-Dichlorobenzene

Ortho-, meta-, and para-dichlorobenzene (1,2-dichlorobenzene, 1,3-dichloro-benzene, 1,4-dichlorobenzene, respectively) are also called o-DCB, m-DCB, and p-DCB. Historically, p-DCB is also known as PDB. The first is used as a solvent, chemical intermediate, and deodorizer; the second has no documented use; and the third is used as a deodorizer and insecticide. For the structures and properties of ortho-, meta-, and para-dichlorobenzene, see Tables 1, 2, and 3, respectively.

Dislodgable leaf residues of insecticides on cotton

In a previous study (Ware et al. 1972) we attempted to show the relative degradation rates of selected organophosphate insecticides on cotton. However, the dislodgable nature of these residues was not taken into consideration, since they were expressed on a ppm basis after being extracted from macerated plant material. It was the purpose of this study to determine the dislodgable or easily removed surface residues of seven commonly used insecticides on cotton over a 4-day period following application. Such information is essential in establishing safe reentry times for personnel working in treated fields.