Lowest observed level

Lu. The spin 9/2 for the lowest observed level in the tt9/2 [514] band was assumed based on systernatics. 

Long-term toxicity tests (commonly referred to as chronic toxicity tests) are used to evaluate whether the extended laboratory exposure to a chemical will adversely affect individuals, species, or populations. These terms may measure effects on development, homeostasis, growth, and reproductive potential to establish the lowest observed level (LOEL), which represents the lowest concentration associated with a measurable effect, and the non-observed effect level (NOEL), which denotes a concentration that did not produce a measurable effect. 

The geometrical parameters are derived from the rotational analysis of 19 bands of the B - X system which are derived from the K=0,1,2,3 sub-levels of a vibronic level at 39157.413(5) cmThis level is the lowest observed level of the B state but may not be the zeroth level. 

Summary of Lowest Observed Effect Levels for Key Lead-Induced Health Effects in Adults... 

Lowest observed effect level (PbB) (Mg/dl) Heme synthesis and hematological effects Neurological effects Renal system effects Gastrointestinal effects ... 

In risk characterization, step four, the human exposure situation is compared to the toxicity data from animal studies, and often a safety -margin approach is utilized. The safety margin is based on a knowledge of uncertainties and individual variation in sensitivity of animals and humans to the effects of chemical compounds. Usually one assumes that humans are more sensitive than experimental animals to the effects of chemicals. For this reason, a safety margin is often used. This margin contains two factors, differences in biotransformation within a species (human), usually 10, and differences in the sensitivity between species (e.g., rat vs. human), usually also 10. The safety factor which takes into consideration interindividual differences within the human population predominately indicates differences in biotransformation, but sensitivity to effects of chemicals is also taken into consideration (e.g., safety faaor of 4 for biotransformation and 2.5 for sensitivity 4 x 2.5 = 10). For example, if the lowest dose that does not cause any toxicity to rodents, rats, or mice, i.e., the no-ob-servable-adverse-effect level (NOAEL) is 100 mg/kg, this dose is divided by the safety factor of 100. The safe dose level for humans would be then 1 mg/kg. Occasionally, a NOAEL is not found, and one has to use the lowest-observable-adverse-effect level (LOAEL) in safety assessment. In this situation, often an additional un-... 

Lowest-Observed-Effect-Level (LOEL) In dose-response experiments, the lowest exposure level at which there are statistically or biologically significant increases in the frequency or severity of any effect between the exposed population and its appropriate control group. 

LOAEL lowest-observed-adverse-effect level... 

Cardio - cardiovascular LD = Lethal dose, 50% kill LOAEL = lowest-observable-adverse-effect level mg/kg/day = milligram per kilogram per day NOAEL = no-observable-adverse-effeot level... 

Tables (3-1, 3-2, and 3-3) and figures (3-1 and 3-2) are used to summarize health effects and illustrate graphically levels of exposure associated with those effects. These levels cover health effects observed at increasing dose concentrations and durations, differences in response by species, minimal risk levels (MRLs) to humans for noncancer end points, and EPA s estimated range associated with an upper- bound individual lifetime cancer risk of 1 in 10,000 to 1 in 10,000,000. Use the LSE tables and figures for a quick review of the health effects and to locate data for a specific exposure scenario. The LSE tables and figures should always be used in conjunction with the text. All entries in these tables and figures represent studies that provide reliable, quantitative estimates of No-Observed-Adverse-Effect Levels (NOAELs), Lowest-Observed-Adverse-Effect Levels (LOAELs), or Cancer Effect Levels (CELs).

LOAEL A Lowest-Observed-Adverse-Effeet Level (LOAEL) is the lowest dose used in the study that caused a harmful health effect. LOAELs have been classified into "Less Serious" and "Serious" effects. These distinctions help readers identify the levels of exposure at which adverse health effects first appear and the gradation of effects with increasing dose. A brief description of the specific end point used to quantify the adverse effect accompanies the LOAEL. The respiratory effect reported in key number 18 (h q)erplasia) is a Less serious LOAEL of 10 ppm. MRLs are not derived from Serious LOAELs. 

Levels of significant exposure for each route and duration are presented in tables and illustrated in figures. The points in the figures showing no-observed-adverse-effect levels (NOAELs) or lowest-observed-adverse-effect levels (LOAELs) reflect the actual doses (levels of exposure) used in the studies. LOAELS have been classified into "less serious" or "serious" effects. "Serious" effects are... 

Bd Wt = body weight Cardio = cardiovascular d = day(s) Endocr = endocrine F = female Gastro = gastrointestinal Hemato = hematological hr = hour(s) LC50 = lethal concentration, 50% kill LOAEL = lowest- observable-adverse-effect level M = male Musc/skel = musculoskeletal ... 

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