摘要:

Methyl parathion is a widely used agricultural insecticide, and the recent unlicensed use of this compound in homes has led to the evacuation of approximately 1100 persons in Mississippi. Although the primary concern in such cases of acute exposure is neurotoxicity, a few organophosphorus compounds apparently have immunotoxic effects at dosages that do not produce neurotoxic symptoms. The purpose of the present study was to determine if this is the case for methyl parathion. Female B6C3F1 mice were exposed to methyl parathion by gavage, daily for 7, 14, 21, or 28 d (at 6 mg/kg/ d). Exposure for 14-28 d produced significant, dose-responsive inhibition of acetylcholinesterase (the target molecule for methyl parathion-induced neurotoxicity) in brain or plasma, indicating that the compound was active. The following immunological parameters were evaluated: white blood cell counts and differentials, spleen and thymus weight and cellularity, splenic natural killer cell activity, nitrite production by peritoneal macrophages following activation in vitro, antibody response to sheep erythrocytes in vitro and in vivo, the cytotoxic T lymphocyte response to allogeneic tumor cells, and resistance to Streptococcus agalactiae and B16F10 melanoma cells. Methyl parathion at 1 or 3 mg/ kg/d significantly increased splenic natural killer cell activity. Nitrite production by macrophages was increased in mice treated with 1, 3, or 6 mg/ kg/d. The antibody response to sheep erythrocytes in vitro was significantly suppressed, but the humoral response to sheep erythrocytes in vivo was not affected. The cytotoxic Tlymphocyte response to allogeneic tumor cells was not significantly affected. Host resistance was not significantly decreased. Although it remains possible that immunological parameters not tested here may be affected by methyl parathion, the present results do not suggest substantial immunotoxic potential for this compound.

ISSN:1528-7394    

DOI:10.1080/009841098158999

出版商:Informa UK Ltd    

年代:1998

数据来源: Taylor

摘要:

Many pesticides are used in the agricultural environment, and some may have the potential to disrupt reproductive or endocrine function. Ewes, in separate groups of 6, received orally into their rumen either empty gelatin capsules or capsules containing chlorpyrifos (12.5 mg/ kg), trifluralin (17.5 mg/ kg), lindane (2.5 mg/ kg), or pentachlorophenol (2 mg/kg) 2 times per week for 43 d. Dimethoate (0.2 mg/kg), carbofuran (0.30 mg/kg), 2,4-dichlorophenoxyacetic acid (10 mg/kg), or triallate (5 mg/kg) was given 3 times per week. After 36 d of treatment, blood samples were taken every 12 min for 6 h for hormone analysis. Ewes were euthanized at the end of the study for necropsy and histopathology. No overt signs of toxicity were seen, and body weight was not affected by treatment. Carbofuran caused a significant increase in serum concentrations of thyroxine compared to control ewes, but all other pesticides, except trifluralin, resulted in a marked decrease in thyroxine concentrations. Serum concentrations of cortisol were significantly increased by trifluralin and chlorpyrifos. Concentrations of insulin in serum were markedly increased in ewes given dimethoate, lindane, trifluralin, triallate, and pentachlorophenol, and concentrations of estradiol were also significantly increased in ewes given lindane and trifluralin. Mean serum concentrations of LH were markedly decreased by trifluralin, and basal LH concentrations were significantly decreased by lindane, dimethoate, and trifluralin but increased by triallate. Both pentachlorophenol and triallate caused a significant increase in severity of oviductal intraepithelial cysts in ewes. Data suggest that several currently used pesticides could influence serum concentrations of reproductive and metabolic hormones, particularly thyroxine, the major secretory product of the thyroid and a principal regulator of metabolism.

ISSN:1528-7394    

DOI:10.1080/009841098159006

出版商:Informa UK Ltd    

年代:1998

数据来源: Taylor

摘要:

It has been reported that nickel (Ni) crosses the human placenta and produces teratogenesis and embryotoxicity. In the present study, the effects of nickel on human term placentas were investigated. In time-course experiments, placental tissue was incubated for 3, 6, 12, or 24 h with 2.5 m M Ni. The viability as determined by glucose consumption rate did not show any significant change from 3 to 12 h, whereas the permeability, lipid peroxidation, and Ni concentration were significantly increased compared to the control. In concentration-response studies, placental explants were incubated with 0.5, 1.0, 2.5, or 5 m M Ni for 12 h. The viability did not change significantly, except for 5 m M Ni, but the permeability and lipid peroxidation increased markedly in a concentration-dependent manner. Treatment with ascorbic acid or Zn decreased placental lipid peroxidation and permeability induced by Ni, but had no effect on lowering the Ni tissue content. Data show that Ni is toxic as evidenced by lipid peroxidative damage to placental membrane, and this metabolic change may be responsible for decreased placental viability, altered permeability, and potential subsequent embryotoxicity.

ISSN:1528-7394    

DOI:10.1080/009841098159015

出版商:Informa UK Ltd    

年代:1998

数据来源: Taylor

摘要:

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.

ISSN:1528-7394    

DOI:10.1080/009841098159024

出版商:Informa UK Ltd    

年代:1998

数据来源: Taylor

摘要:

Electromagnetic-related alteration of cellular functions is well documented for extremely low-frequency low-energy pulsing electromagnetic fields (ELF-EMF). In this study we examined the in vitro effects of static magnetic fields (SMF) on the cellular immune parameters of the C57Bl/ 6 murine macrophages, spleen lymphocytes, and thymic cells. The cells were exposed in vitro for 24 h at 37 C, 5% CO2, to 250-1500 G SMF. Exposure to the SMF resulted in the decreased phagocytic uptake of fluorescent latex microspheres, which was accompanied by an increased intracellular Ca2+ level in macrophages. Exposure to SMF decreased mitogenic responses in lymphocytes, as determined by incorporation of \[3H]thymidine into the cells. This was associated with the increased Ca2+ influx in concanavalin A-stimulated lymphocytes. Furthermore, exposure to SMF produced markedly increased apoptosis of thymic cells, as determined by flow cytometry. Overall, in vitro exposure of immunocompetent cells to 250-1500 G SMF altered several functional parameters of C57Bl/6 murine macrophages, thymocytes, and spleen lymphocytes.

ISSN:1528-7394    

DOI:10.1080/009841098159033

出版商:Informa UK Ltd    

年代:1998

数据来源: Taylor