Ceiling concentration

Acceptable ceiling concentration permitted by federal OSH A. standards. 

If the Hill coefficient is less than one (H < 1), the maximum effect will never be obtained with increasing concentrations (E < max). If the Hill coefficient is more than ten (H > 10), an on-off phenomenon can be described at CE50. The effect can be assumed to be marginal and less than 5% of max for the threshold concentration (CE05) but almost 95% of max for the ceiling concentration (CE95). 

Pharmacokinetics. Figure 2 Sigmoid Emax model of pharmacodynamics with Hill coefficient (H), concentration producing half-maximum effect (CE50), threshold concentration (CE05), and ceiling concentration (CE95). 

AUEC = 1.44 Tl /2 (Emax/H) ln( 1 + (Co/CE50) A/Z) For irreversible effects no ceiling concentration is assumed the incremental increase in concentrations and the absolute height of the peak might be more impacting. 

EPA has established that hydrogen sulfide is a regulated toxic substance and is a hazardous substance as defined under the Federal Water Pollution Control Act. OSH A has established an acceptable ceiling concentration of 20 parts per million (ppm) for hydrogen sulfide in the workplace, with a maximum level of 50 ppm allowed for 10 minutes maximum duration if no other measurable exposure occurs. NIOSH has set a maximum Recommended Exposure Limit (REL) ceiling value (10 minutes) of 10 ppm. A complete listing of federal and state regulations and recommendations are found in Chapter 7. 

PEL-Acceptable Ceiling Concentration 20 ppm OSHA 1998c (29 CFR 1910.1000 Table Z-2)... 

TLVs established by the ACGIH, including short-term exposure limits (TLV-STELs) and ceiling concentrations (TLV-Cs),... 

The PELs are promulgated by OSHA and have force of law. These levels are similar to the ACGIH criteria for TLV-TWAs because they are also based on 8-hr time-weighted average exposures. OSHA-cited acceptable ceiling concentrations, excursion limits, or action levels may be appropriate for use as benchmarks. 

TIN-TWA Threshold limit value, time-weighted average for 8-h exposures, with ceiling concentrations shown as C, and with skin absorption hazard as S. The OSHA permissible exposure limit (PEL) is the lower of the TWA or the ceiling limit. 

Ceiling concentrations (TLV-C) are concentrations that should not be exceeded at any time. 

Mouse (Swiss- Webster) Gd 0 - PND 180 spleen weights depressed spleen ceil concentrations of interleukin-2, interferon-g and tumor necrosis factor-a deficiency of 004-1- cells in T-cell populations) Golub et al. 1993b C,HlsAIO,... 

A verification experiment under the conditions of 12 g/L for yeast extract, 0.6 g/L for KH2P04, and 0.6 g/L for MgS04 was conducted separately in order to confirm the optimal conditions obtained from the statistically based experimental designs. After 24 h of fermentation, 92.1 mg/L of nisin and 19.3 g/L of lactic acid were obtained. This result was very close to the predicted value of 92.9 mg/L of nisin and 19.3 g/L of lactic acid. In addition, the nisin result also agreed well with the "ceiling concentration" of nisin previously reported by Kim et al. (23). Therefore, the optimal conditions predicted from the statistically based experimental designs were valid. 

The "ceiling" concentration was not determined in this survey because samples must be taken for a sampling period of only 10 minutes. However, "ceiling" concentrations can be estimated under a "worst" possible instance by assuming that all of the material was collected during a time interval of 10 minutes. By using the relationship ppm = 24450 x mg/L... 

OSHA Acceptable ceiling concentration 20 ppm (28 mg/m3) OSHA 1997a... 

Maximum Peak Above the Acceptable Ceiling Concentration for an 8 hr Shift 50 ppm (10 min)b ... 

Exposure limits OSHA has recommended the PEL for perchloroethylene as 100 ppm for 8 hours (TWA). The acceptable ceiling concentration is 200 ppm for 5 minutes in any 3-hour period, not to exceed a maximum peak of 300 ppm. ... 

Glucose-to-ethanol fermentation is to be carried out in a batch reactor using an organism such as Saccharomyces cerevisiae. Plot the concentrations of cells, substrate, and product and growth rates as functions of time. The initial ceil concentration is 1.0 g/dm and the substrate (glucose) concentration is 250 g/dm. ... 

The Occupational Safety and Health Administration permissible exposure limit is 3 ppm (lOmgm ) as an 8h, time-weighted average. The American Conference of Governmental Industrial Hygienists and National Institute for Occupational Safety and Health recommend 3 ppm as a ceiling concentration. The Revised (1996) IDLH level is 30 ppm. The temporary emergency exposure limits (TEELs) are TEEL-0, TEEL-I, and TEEL-2 (pgm ) 10000 TEEL-3 (pgm ) 100 000. 

Mine Safety and Health Administration (MSHA) Standard air ceiling concentration is 5 mg (Mn)... 

FDA has approved the use of Bisphenol A as an component used to make polyarylate or 4,4 -Isopropylidenediphenol-epichlorohydrin resins to be used for single and repeated use food contact surfaces as outlined in 21CFR177, Parts 1440 and 1555. OSHA PEL in Shipyards ceiling concentration 0.5 ppm (2.8 mg/m3). 

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