Baseline concentrations

PSD Increments the maximum increase in ambient pollution concentrations allowed over baseline concentrations. See 40 CFR 51.166 (c) for increments for specific pollutants. 

Initiation of long-term environmental monitoring studies in terrestrial and aquatic ecosystems to establish appropriate baseline concentrations and to separate these from contaminant effects (Kum-plainen and Koivistoninen 1977 WHO 1980 Hall and Pinkney 1985 Thompson et al. 1985). 

Derwent, R. G., P. G. Simmonds, S. O Doherty, P. Ciais, and D. B. Ryall, European Source Strengths and Northern Hemisphere Baseline Concentrations of Radiatively Active Trace Gases at Mace Head, Ireland, Atmos. Environ, 32, 3703-3715 (1998b). 

Even before the first small facility was placed into operation, the field operators funded an environmental survey to determine baseline concentrations of hydrogen sulfide, sulfur dioxide, and particulates in the air. As might be expected in a rural area, no measurable concentrations of sulfur compounds were observed. The baseline survey also included soil, water, and vegetation sampling throughout the field to determine the before condition of the local environment. A 1-year biological study of the Escambia River and adjacent uplands near the field was also conducted by the U. of West Florida. 

In a 15-year-old boy with previously quiescent lupus nephritis, laboratory markers of disease activity rose during somatropin treatment and returned to baseline concentrations within 3 months after withdrawal (88). 

In 14 asymptomatic patients statin therapy worsened left ventricular diastolic function co-enzyme Q10 supplementation produced improvement. There were several limitations of this study, including a small sample size and the lack of a control arm, but the patients did serve as contemporary controls for themselves. Because baseline concentrations of co-enzyme Q10 do not predict dysfunction, routine concomitant co-enzyme Q10 administration, especially in patients at risk, may be prudent (5). 

Chen, M., Ma, L.Q. and Harris, W.G. (1999) Baseline concentrations of 15 trace elements in Florida surface soils. Journal of Environmental Quality, 28(4), 1173-81. 

In the case of trastuzumab, where shed antigen is found in the circulation, high antigen concentrations resulted in lower trough trastuzumab concentrations. This effect was modeled using only a linear clearance term and the shed antigen baseline concentration as covariate. 

Cicchella, D., De Vivo, B., and Lima, A. (2005). Background and baseline concentration values of elements harmful to human health in the volcanic soils of the metropolitan and provincial area of Napoli (Italy). Geochem. Explor. Environ. Anal. 5, 29-40. 

Barbaris and Betterton, 1996) are also slightly above baseline concentrations, probably because of inputs from smelters, power plants, and soil dust. In most industrialized countries, sources of airborne arsenic are limited as a result of air-pollution control measures. Unless significantly contaminated, atmospheric precipitation contributes little arsenic to surface waters. 

A (congenital or acquired) and type 1 von Willebrand disease, in which the VWF protein structure is normal but the plasma concentration is reduced (1). By contrast with conventional coagulation factor concentrates, desmopressin is cheap and is free from the risk of transmission of viral infections, which have proved such a problem in the past. It is also very useful in the treatment of carriers of hemophilia A, many of whom have significant reductions in the baseline concentration of factor VIII. By contrast, desmopressin has no effect on the concentration of factor IX, and is thus of no value in hemophilia B (Christmas disease). It is also of little value in type 2 (abnormal VWF structure) von Willebrand s disease, which accounts for about 15-20% of all cases. The administration of desmopressin to patients with type 2B von Willebrand s disease can be hazardous, as it is likely to cause thrombocytopenia (2). The use of desmopressin in bleeding disorders has been reviewed (3). Tachyphylaxis develops if desmopressin is used for prolonged periods to control bleeding disorders, because desmopressin causes release of stored factor VIII and von Willebrand factor, after which it takes time for them to accumulate again. 

This procedure is designed to provide analytical data to show compliance with existing standards. In addition, it can be used to determine baseline concentrations of the transuranium nuclides in the environment. 

The experimental scheme for anaerobic decomposition is shown in Fig. 5-4. Exactly 1.5 g of each substrate was added to a modified 1 litre Sohngen flask and autoclaved at 120°C and 15 psi to ensure sterility, after which each flask was filled to capacity with a sterile inorganic nutrient medium and pH adjusted. Next 50 ml of a heterogeneous innoculum prepared from muds from a local lake was injected into each flask as "inoculates", while 50 ml. of sterile nutrient medium was used for control samples. Headspace C1-C4 hydrocarbons were measured prior to incubation to provide baseline concentrations. Minimum detection limits were 3 ppb on a volume basis using a high-sensitivity gas chromatograph equipped with a flame ionisation detector. Samples were incubated at 25°C and 36°C over a five week period. 

The baseline concentration of mercury in unpolluted marine waters has been estimated to be less than 2 ng/L (2 ppt) (Fowler 1990). In contrast, the New York Bight, an inshore coastal area near the industrialized areas of New York Harbor and northern New Jersey, contained dissolved mercury concentrations in the range of 10-90 ng/L (ppt) (Fowler 1990). 

The log of the slope (K) of the terminal-elimination phase of an observed time-concentration curve for an individual (obtained from the last three to four PK observations) was used to build a subtraction curve between time t = 0 and t = t equal to Co exp(-Kt) with ESM. The value of this curve was subtracted from the true observation, at the time of each actual observation, and these differences were analyzed as though they were the observed PK responses to a single dose. The authors included this method to imitate what is often done in practice when baseline concentrations are clearly nonzero and prior dosing history is deemed to be unreliable or unavailable. 

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