Experimental exposure of rats to methylene chloride at varying controlled barometric altitudes
This study investigated combined effects of three methylene chloride (MC) volume/volume concentrations (0,50, and 500 ppm) at three controlled barometric altitudes (760, 640, and 560 torr). This provided a three by three study design. For each scenario, three altitude acclimated (6 days) adult male rats were studied for eight hours in a nose-only inhalation chamber. Blood (0.35 mL) was drawn from the cannulated left carotid artery of each rat at 0, 0.5, 1, 2, 4, and 8 hours and hematocrit, pO[sub 2], pCO[sub 2], pH , total hemoglobin (Hb) and carboxyhemoglobin (CHb) were measured. Time, MC concentration and altitude had significant effects on CHb production. CHb increased with increasing MC concentration over time. Increased barometric altitude (reduced partial pressure of MC vapor at altitude for equal ppm concentrations) resulted in lower blood CHb levels. A statistical model was derived to explain variation in CHb levels for these three independent variables (r = 0.983). The data were applied to an equation assessing the impact of altitude, MC concentration and time on the potential oxygen carrying capacity (POCC) of blood. The POCC of HB in the blood was calculated using blood Hb, CHb levels, Hb oxygen saturation (based on the blood pO[sub 2] and the oxygen dissociation curve for rats), and oxygen binding potential of Hb. It was determined for the altitudes and MC concentrations used, polycythemia associated with increased altitude had a greater impact on POCC than decreased pO[sub 2]. A regression equation was derived modeling variation in POCC of blood for the three independent variables (r = 0.995). This study demonstrated that altitude affects airborne ppm MC concentrations. This ultimately impacts CHb levels and oxygen carrying capacity of the blood. These finding indicate that occupationally acceptable ppm MC exposure levels at altitude do need barometric pressure correction.
- Research Organization:
- Colorado State Univ., Fort Collins, CO (United States)
- OSTI ID:
- 7013284
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
METHYLENE CHLORIDE
BIOLOGICAL EFFECTS
BLOOD CHEMISTRY
CARBOXYHEMOGLOBIN
ENVIRONMENTAL EXPOSURE
HEMOGLOBIN
INHALATION
MATHEMATICAL MODELS
PRESSURE EFFECTS
RATS
REGRESSION ANALYSIS
TIME DEPENDENCE
ANIMALS
BIOCHEMISTRY
CARBOXYLIC ACIDS
CHEMISTRY
GLOBINS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INTAKE
MAMMALS
MATHEMATICS
ORGANIC ACIDS
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PIGMENTS
PORPHYRINS
PROTEINS
RODENTS
STATISTICS
VERTEBRATES
560300* - Chemicals Metabolism & Toxicology