Erythrocyte count

Hematological Effects. No information was found regarding hematological effects in humans following exposure to methyl parathion. Repeated oral exposure to methyl parathion resulted in decreased mean corpuseular volume in one study and decreased hematocrit and erythrocyte count in another study in rats. Chronic ingestion of methyl parathion induced reduction of mean hemoglobin, hematocrit, and erythrocyte eounts in rats. 

ATSDR has derived a chronic-duration oral MRL of. 0003 mg/kg/day for methyl parathion based on a NOAEL of 0.025 mg/kg/day for reduced hematocrit and erythrocyte counts in rats (Suba 1984). 

EPA has derived an RfD of. 00025 mg/kg/day, based on a NOAEL of 0.025 for reduced hematocrit, erythrocyte counts, and hemoglobin (cholinesterase inhibition was also listed as a critical effect but the reason for this was not explained). This NOAEL appears to be from the same study as for the ATSDR chronic-duration oral MRL, although the study is referenced differently (IRIS 2001). 

Effects noted in study and corresponding concentrations No adverse effects were observed in the low-dose male and female rats. Mean hemoglobin, hematocrit, and erythrocyte counts were significantly reduced in the high-dose females at 6-24 months of treatment mean hematocrit and erythrocyte counts were significantly reduced in the mid- and high-dose males at 24 months of treatment. 

Concentration and end point used for MRL derivation 0.025 mg/kg/day decreased mean hematocrit and erythrocyte counts... 

Other additional studies or pertinent information that lend support to this MRL An intermediate-duration gavage study in rats found decreased hematocrit and erythrocyte counts relative to before-treatment values (Galal et al. 1977), but this study had some limitations, including lack of a control group and disparities between text and tables. Another intermediate duration gavage study in male rats demonstrated dose-related significant decreases in mean corpuscular volume (Undeger et al. 2000). An effect on the erythrocyte is plausible because erythrocyte cholinesterase has a function in the control of erythrocyte permeability (Wills 1972). 

Erythrocyte count (blood) See under red blood cell count Erythrocyte sedimentation rate (ESR) Westergren ... 

In a study by Kensler et al. (1946), three monkeys were exposed by inhalation to arsine at a concentration of 0.45 mg/L (450 mg/m3 or 140 ppm) for 15 min. Although one monkey died in 24 h, one remaining monkey survived without treatment another was treated with 2,3-dimercaptopropyl ethyl ether. The surviving monkey that was not treated could "scarcely raise himself from the floor of his cage from the 2nd to the 7th days." The erythrocyte count of this monkey decreased to 65% of pre-treatment level in 24 h, and by d 3 1 decreased to approximately 20% prior to recovery. The monkey treated with... 

While hemoglobin adduct formation does not imply altered or abnormal hemoglobin function, adduct formation may be a suitable biomarker of human exposure to 3,3 -dichlorobenzidine (see Section 2.7). Hematological variables (erythrocyte count, hemoglobin concentration, hematocrit, and leucocyte count) were found to be normal in dogs exposed to 10.4 mg/kg/day 3,3 -dichlorobenzidine for 7 years (Stula et al. 1978). 

Decreases in hemoglobin concentration and increases in erythrocyte, white blood cell, and polymorphonuclear leukocyte concentrations were noted in mice after acute dermal exposure to kerosene. A decrease in the splenic relative weight, which was not accompanied by histopathological changes, was also noted (Upreti et al. 1989). Oral exposure to JP-5 increased hematocrit levels, decreased white blood cell counts, and increased erythrocyte counts in rats (Parker et al. 1981). However, inhalation of diesel fuel aerosol induced decreases in the mean red blood cell count in rats and had no effect on white blood cells (Dalbey et al. 1987). 

Body weight and food/water consumption Hematology (haematocrit, hemoglobin, erythrocyte count, total and differential leucocyte count, platelet count, blood clotting time/potential)... 

Hamsters repeatedly exposed to 4500 ppm for 3 months had growth retardation, ocular and nasal irritation, increased erythrocyte counts, and severe histopathological changes in the respiratory tract. ... 

In a subchronic inhalation study, rabbits exposed to 98 ppm 7 hours/day, 5 days/weekfor 6 months showed hemoglobin depression with some methemoglobin, elevated serum car-bamyl transferase, and thyroxin depression. For rats similarly exposed at 745 ppm, there was altered hematocrit, hemoglobin, and erythrocyte counts, altered prothrombin time, and increased thyroid weight. 

In rats, the oral LDso of several zirconium compounds ranged from 1.7 to lOg/kg. Animals acutely poisoned by zirconium compounds show progressive depression and decrease in activity until death. Repeated inhalation of zirconium tetrachloride mist by dogs for 2 months at 6 mg zirconium/m caused slight decreases in hemoglobin and in erythrocyte counts, with some increased mortality over that of controls. These effects may have been due to the liberation of hydrogen chloride. Animals exposed to zirconium dioxide dust for... 

Drug/Lab test interactions Over the course of 24 months, patients treated with dipyridamole and aspirin combination therapy showed a decline (mean change from baseline) in hemoglobin of 0.25 g/dL, hematocrit of 0.75%, and erythrocyte count of 0.13 X 10 /mm2. 

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