Effects of a mixture of vegetable and essential oils and fatty acid potassium salts on Tetranychus urticae and Phytoseiulus persimilis.

Laboratory trials were carried out to evaluate the toxicity and the influence of a commercial mixture of vegetal, essential oils, and potassium salts of fatty acids (Acaridoil 13SL) on the population growth rate (r(i)--instantaneous rate of increase) of two mite species, the phytophagous Tetranychus urticae Koch and the predator Phytoseiulus persimilis Athias-Henriot. A residue of 1.3 mg/cm(2) of pesticide solution was harmless for Ph. persimilis eggs, while a moderate mortality of eggs and of larvae from treated eggs of T. urticae, was observed (53.8%). The pesticide also caused a delay in the postembryonic development of the tetranychid. Moreover, 83.4% mortality was reported for treated females tetranychids and only 24.0% for Ph. persimilis females. The pesticide influenced negatively the population growth of T. urticae which showed a very low rate of increase (r(i)=0.07), compared to that obtained in the control (r(i)=0.68). The pesticide did not affect negatively the reproductive potential of Ph. persimilis (r(i)=0.54 and r(i)=0.57 for test and control, respectively). These results suggest a considerable acaricidal activity of potassium salts of fatty acids and caraway oil on T. urticae and a good selectivity on Ph. persimilis.

Differential response of Tilapia guineensis fingerlings to inorganic fertilizer under various salinity regimes.

The influence of salinity on the response of the estuarine teleost, Tilapia guineensis fingerlings to acute toxic effects of inorganic nitrogen-phosphorus-potassium (NPK) (15: 15: 15) fertilizer was investigated using semi-static bioassay. The toxicity of NPK fertilizer was found to increase significantly with increase in the salinity level from 0.05 %. to 32.4 %o. The 96 hr LC50 value at salinity of 32.4 %o was 0.11 mg/l and was found to be significantly (p < 0.05) higher than the toxicity values at any other salinity level of media evaluated. The implication of the findings is that pollution control standards and/or safe limits for brackish water ecosystem should consider variations in salinity regimes for greater relevance and reliability.

A subacute inhalation exposure evaluation of a scrubbing solution used in petroleum refineries.

The potential for subacute toxicity and neurotoxicity of a potassium carbonate-based scrubbing solution used in petroleum refineries was evaluated in Sprague-Dawley Crl:CD BR rats. Exposures were to aerosols of a "used" scrubbing solution by wholebody inhalation, 6 h/d, for 21 consecutive days at target concentrations of 0 (filtered air-control), 0.1, 0.2, or 0.4 mg/L (30 animals/sex/group). A functional observation battery (FOB) and locomotor activities tests were conducted and monitored. No apparent adverse effects were noted at any exposure level as determined by clinical observations, food consumption, hematology, serum chemistry, ophthalmologic observations, and gross pathology. Statistically significant increases in lung weights were noted at all treatment levels but returned to control values upon cessation of exposure except for the 0.4 mg/L female group. There were no significant changes in other organ weights. Histopathologic findings were restricted to the respiratory tract and characterized by minimal to moderate epithelial hyperplasia, epithelial necrosis, and cytoplasmic vacuolation at levels I and II of the nasal cavities. Lung bronchiolization and alveolar macrophage infiltration were also observed. The respiratory-tract findings were considered a local response to the high alkalinity of the test material as substantiated by the return to normal upon cessation of exposure. Exposure to scrubbing solution had no adverse effect on FOB endpoints and locomotor activity evaluations, brain weight and size, and neuropathologic examinations. In conclusion, inhalation exposure to a used scrubbing solution aerosol for 21 d did not result in any persistent systemic toxicity or neurotoxicity in either male or female rats.

Developmental toxicity evaluation of a scrubbing solution used in petroleum refineries.

The developmental toxicity potential of a scrubbing solution used extensively in petroleum refineries to remove CO2 from hydrogen gas streams was evaluated via inhalation. Pregnant female CD (Sprague-Dawley) rats were exposed to aerosols of a "used" scrubbing solution at 0.05, 0.1, 0.2, or 0.3 mg/l for 6 h/d on d 6-19 of pregnancy. Control animals were exposed to filtered air under the same exposure conditions. Dams were sacrificed on d 20 of pregnancy and a laparohysterectomy was performed. The mass median aerodynamic diameter of the aerosol revealed that all particles ranged from 1.6 to 2.8 microm, with geometric standard deviations between 2.0 and 2.3 microm. The overall pregnancy rate was high (>95%) and equivalent across all groups. All pregnant dams had live litters, and 22-24 litters were examined in each group. Treatment-related clinical signs consisted of rales, observed at all exposure levels, and gasping noted only at the 0.3 mg/l exposure level. The occurrence of rales was presumably a localized effect on the respiratory tract and likely due to the irritating properties of the scrubbing solution. Maternal toxicity was exhibited in the 0.3 mg/l group, including reduced body weight, weight gain, and food consumption and one possible treatment-related death on gestation d 17. At scheduled necropsy, there were no treatment-related gross pathological observations and no statistically significant reproductive and developmental effects. The incidences of fetuses with skeletal variations involving the sternum were clustered in two litters at the highest exposure level with atypically low term fetal body weights. Under the conditions of this investigation, potassium carbonate scrubbing solution is not a selective developmental toxicant.

The use of a scanning proton microprobe to observe anti-HIV drugs within cells.

A series of inorganic polyanions (viz. heteropolytungstates) has been shown to have antiviral activity but there was no evidence to indicate that the drugs reached their site of antiviral (HIV) activity intact. We have shown that with a scanning proton microprobe it is possible to analyse the metal content of individual cells (PBLs) treated with such a polyoxometalate drug and to determine the atomic ratio of the metals within the cell. This was found to be near that in the drug. The distribution of the metals (tungsten and cobalt) within the cell was measured and it was shown that both metals were located in the same region within the cell. These findings would suggest that the drug had entered the cells intact.

L-ascorbic acid amplification of bladder carcinogenesis promotion by K2CO3.

The dose dependence of K2CO3 promotion of two-stage urinary bladder carcinogenesis and the amplifying effects of additional L-ascorbic acid (AsA) administration were investigated. Male F344 rats were given 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine in their drinking water for 4 weeks and then fed basal diet containing K2CO3 at levels of 0, 1, 1.5, 2.2, and 3% with or without 5% AsA or 3% NaHCO3 supplementation from weeks 5 to 8 (4 weeks) and weeks 12 to 20 (9 weeks). During weeks 9 to 11 (3 weeks), the rats were fed 3% uracil in their diet. For controls, rats without N-butyl-N-(4-hydroxybutyl)nitrosamine treatment were given either 3% K2CO3, 5% AsA, or both plus the uracil treatment. The total observation period was 20 weeks. K2CO3 dose dependently increased the numbers of the putative preneoplastic lesion, papillary or nodular hyperplasia, and papillomas in rats initiated with N-butyl-N-(4-hydroxybutyl)nitrosamine. AsA (5%), while itself exerting no promoting effect, amplified the enhancing influence of K2CO3 on the induction of papillary or nodular hyperplasia and papillomas. The dose-dependent elevation of urinary pH and K+ concentration was associated with K2CO3 treatment with or without AsA. Thus, increased urinary pH and K+ concentration appear to play important roles in K2CO3 promotion, and AsA amplifies this promotion.

[Toxicologic characteristics and hygienic standardization of the levels of sodium hydrocarbonate and potassium carbonate in the air of the work area]. / Toksikologicheskaia kharakteristika i gigienicheskoe normirovanie soderzhaniia gidrokarbonata natriia i karbonata kaliia v vozdukhe rabochei zony.

Toxicity and hazards of sodium hydrocarbonate (SH) and potassium carbonate (PC) were experimentally assessed. Both substances caused impairments of electrolytic equilibrium, protein metabolism, changes of functional and biochemical indicators of the cardiovascular system, etc. LD50 of SH for white rats constituted 9940 +/- 350 mg/kg, for mice 3360 +/- 210 mg/kg and of PC 2980 +/- 142 and 2570 +/- 142 mg/kg, respectively. The authors failed to define mean lethal concentrations of both substances. The following threshold values Limac were established at 74 mg/m3 for SH and at 54 mg/m3 for PC. Limch was respectively 14.9 and 4.7 mg/m3. MAC for SH was established at 5 mg/m3 and for PC at 2 mg/m3.

K+-induced motility and depolarization of cochlear hair cells. Direct evidence for a new pathophysiological mechanism in Ménière's disease.

In addition to an endolymphatic hydrops in various models of Ménière's disease, ruptures of the membranes lining the endolymphatic spaces or massive changes in their biochemical permeability are believed to allow large amounts of potassium-rich endolymph to deluge the normally low [K+] perilymphatic fluid. Our clinic has shown that exposure of the lateral and basal membrane parts of living isolated outer hair cells to increasing concentrations of potassium ions resulted in a sustained reversible cellular depolarization. Furthermore, potassium intoxication was accompanied by a strictly longitudinal contraction of the hair cells present. This was followed by hair cell relaxation in the presence of artificial perilymph. These findings suggest a supplementary hypothesis for the clinical manifestations of Ménière's disease: the reversible hair cell depolarization can explain the sudden tinnitus and parts of the hearing loss incurred as well as presumably the vertigo experienced; the reversible longitudinal hair cell contraction induces an abnormal change of cochlear micromechanics, resulting in concomitant attacks of deafness and also possibly contributing to the tinnitus perceived.

Significance of L-ascorbic acid and urinary electrolytes in promotion of rat bladder carcinogenesis.

The present studies report on the significance of L-ascorbic acid (AA) and urinary electrolytes for promotion of rat urinary bladder carcinogenesis. Male F344 rats were given an oral administration of 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) as an initiator for 4 weeks, and were then subjected to treatment with dietary supplements of test chemicals for 32 weeks. Administration of 5% sodium L-ascorbate (SA), the sodium ion form of AA significantly promoted urinary bladder carcinogenesis, whereas administration of 5% AA did not. The urine of rats given SA but not AA was characterized by an apparent elevation of pH, an increase of sodium ion concentration, and increases in the urinary content of total AA and its metabolite, dehydroascorbic acid. Administration of 3% NaHCO3, which induced elevation of pH and increase of sodium ion concentration in the urine, promoted BBN bladder carcinogenesis. When rats were given 5% AA plus 3% NaHCO3, AA enhanced the promoting activity of NaHCO3. Lowering of pH by 1% NH4Cl clearly reduced the promoting activity of 5% SA when these two compounds were given concurrently. Treatment with 5% AA plus 3% K2CO3 promoted BBN bladder carcinogenesis in rats, whereas addition of 5% CaCO3 or 5% MgCO3 to AA did not. These results strongly indicate the important role of urinary sodium or potassium ion concentration and pH in modulating urinary bladder carcinogenesis by AA.