Spleen weight

Male mice exposed to 7.3 mg/kg/day for 13 weeks had significantly decreased spleen weights and decreased neutrophil counts (Hoechst 1984b), indicating that immune activity in mice may also be affected. An intermediate-duration oral MRL of 0.005 mg/kg/day was derived based on the NOAEL of 0.45 mg/kg/day for immunotoxicity identified in the Banerjee and Hussain (1986) study. In support of these positive findings, Khurana et al. (1998) observed decreased macrophage functionality, in the absence of any other apparent toxicological effects, in 1-day-old broiler chicks fed 30 ppm endosulfan in the diet for 4 or 8 weeks. 

Histological changes in the spleen related to diisopropyl methylphosphonate intake were not observed in male or female rats exposed to 1 mg/kg/day of diisopropyl methylphosphonate in their drinking water for 26 weeks (Army 1978). As discussed in Section 2.2.2.1, there is some confusion concerning the concentration units and purity of the diisopropyl methylphosphonate used in the Army (1978) study (EPA 1989), and therefore results from the Army (1978) study are considered inappropriate for human health risk assessment. No changes in spleen weight were noted in male or female mink exposed to... 

Consistent with the human responses to arsine exposure, observations in several animal species (rats, mice, and hamsters) indicated hematologic involvement. Cumulative exposures of 540-1,800 ppm-min produced decreases in hematocrit levels, RBC counts, packed cell volumes, and increases in absolute and relative spleen weights (consistent with erythrocyte damage). For acute exposures, the exposure-response curve is steep generally less than a 10-fold difference between no-effect and lethality exposures. 

Key study Blair et al. (1990a). Male and female B6C3Fj mice exposed to arsine at 0.5 ppm for 6 h exhibited no change in relative spleen weights or hematologic parameters and exhibited no overt signs of toxicity. 

Liver contained 156 (68-563) pg PCB 126/kg FW pronounced liver enlargement lymphoid depletion of spleen 10-fold increase in hepatic microsomal EROD and benzyoxyresorufin-O-dealkylase 5-fold increase in methoxyresorufin-O-dealkylase Liver had 380 pg PCB 126/kg FW with increasing necrosis above effects plus decreased bone growth, decreased spleen weight, and degenerative lesions of thyroid Liver had 1.1 (0.6-4.5) mg PCB 126/kg FW above effects plus decreased body weight, decreased hepatic thiol concentrations, and increased plasma enzyme activities... 

There was an increased incidence of a mycoplasma respiratory tract infection in rats exposed to 260 ppm hexachloroethane for 6 weeks but not in rats exposed to lower doses or in other species. This could indicate compromised immune function or a weakened mucosal barrier along the respiratory epithelium. There were no studies identified that evaluated a wide range of immunological parameters. Therefore, there are no reliable LOAELs or NOAELs for this end point. Increases in spleen weights are not classified as LOAELs since they were not accompanied by histopathological changes. 

Rat (Sprague- Dawley) once (GO) 3 F (increase in relative spleen weight, 31% decrease in relative Bagchi et al. 1992b Endrin... 

The only information about the immunological effects of mirex exposure in animals was provided by one acute oral study in rats in which decreased spleen weight was reported (Buelke-Sam et al. 

Immunological Effects. No data on immunotoxicity of mirex in were located. The only information about the immunological effects of mirex exposure in animals was provided by one acute oral study in rats in which decrease spleen weight was reported (Buelke-Sam et al. 1983). Thus, it is uncertain whether persons exposed to mirex at hazardous waste sites might experience adverse effects on the immune system. 

A slight decrease in relative spleen weight was observed in male guinea pigs exposed to 1,4-dichlorobenzene at an air concentration of 173 ppm, 7 hours a day, 5 days a week for 16 days (Hollingsworth et al. 1956) no effect was seen in rats under the same experimental conditions. In a chronic-duration inhalation study, groups of male and female Wistar rats exposed to 1,4-dichlorobenzene 5 hours a day,... 

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