Complex mixtures: Relevance of combined exposure to substances at low dose levels

2013 ◽  
Vol 58 ◽  
pp. 141-148 ◽  
Author(s):  
Winfried R. Leeman ◽  
Lisette Krul ◽  
Geert F. Houben
1989 ◽  
Vol 5 (5) ◽  
pp. 851-867 ◽  
Author(s):  
D. Krewski ◽  
T. Thorslund ◽  
J. Withey

Although procedures for assessing the carcinogenic risks associated with exposure to individual chemicals are relatively well developed, risk assessment methods for mixtures of chemicals are still in the developmental stage. In this paper, we examine the difficulties in assessing the risks of exposure to complex mixtures, with special reference to the potential for synergistic effects among the compo nents of the mixture. Statistical models for describing the joint action of multiple exposures are reviewed, and their implications for low-dose risk assessment are examined. The potential use of pharmacokinetic models to describe the metabolism of mixtures is also considered. Application of these results in regulating mixtures of carcinogenic substances is illustrated using examples involving multiple contaminants in drinking water and polycyclic aromatic hydrocarbons produced from combustion sources.


Author(s):  
Keisuke Maeda ◽  
Kenta Murotani ◽  
Satoru Kamoshita ◽  
Yuri Horikoshi ◽  
Akiyoshi Kuroda

Abstract Background This study examined the association between parenteral energy/amino acid doses and in-hospital mortality among inpatients on long-term nil per os (NPO) status, using a medical claims database in Japan. Methods Hospitalized patients with aspiration pneumonia, aged ≥65 years and on >7-days NPO status, were identified in a medical claims database between January 2013 and December 2018. Using multivariate logistic regression and regression analyses, we examined the association between mean parenteral energy/amino acid doses and in-hospital mortality, and secondarily the association between prognosis (in-hospital mortality, inability to receive full oral intake, re-admission, hospital stay length) among four groups classified by mean amino acid dose (No dose: 0 g/kg/day; Very low dose: >0, ≤0.3 g/kg/day; Low dose: >0.3, ≤0.6 g/kg/day; Moderate dose: >0.6 g/kg/day). Results The analysis population included 20,457 inpatients (≥80 years: 78.3%). In total, 5,920 mortalities were recorded. Increased amino acid doses were significantly associated with reduced in-hospital mortality (p <0.001). With a No dose reference level, the odds ratios (95% confidence interval) of in-hospital mortality adjusted for potential confounders, were 0.78 (0.72–0.85), 0.74 (0.67–0.82), and 0.69 (0.59–0.81) for Very low, Low, and Moderate amino acid doses, respectively. Additionally, patients prescribed amino acid dose levels >0.6 g/kg/day had shorter hospitalization periods than those prescribed none. Conclusions Increased amino acid doses were associated with reduced in-hospital mortality. Sufficient amino acid administration is recommended for patients with aspiration pneumonia requiring NPO status.


2019 ◽  
Vol 74 (7-8) ◽  
pp. 607-611 ◽  
Author(s):  
Hang Bian ◽  
Johann Plank

AbstractWe experimentally investigated the optimum dosage of casein superplasticizer (SP) in self-leveling underlayments (SLUs). The undersaturated adsorption state of casein in cement pore solution was characterized by zeta potential measurements. Different amounts of casein were dosed in SLU pastes and their dispersion performance was investigated by a mini slump test. Flow values of the SLU pastes were found to increase with casein dosage, but an obvious segregation of the pastes was observed at high dose levels of SP. At an SP dosage of 0.12 wt.% bwob (by weight of binder), a homogeneous SLU paste with a spread flow of >15 cm over a time span of 30 min was obtained, which was identified as the optimum casein dosage for SLUs. Casein was found to adsorb significantly onto the surface of cement, thus producing strong dispersive power at low dose levels.


1994 ◽  
Vol 40 (2) ◽  
pp. 206-210 ◽  
Author(s):  
S A Winfield ◽  
N D Boyd ◽  
M J Vimy ◽  
F L Lorscheider

Abstract An ultrasensitive method for determining total mercury concentrations in biological specimens is a prerequisite for monitoring exposure to chronic low-dose levels of Hg vapor such as those from dental silver amalgam fillings. The clinical consequences of such doses are currently in question. We describe an adaptation of a two-stage gold amalgamation preconcentration step combined with cold vapor atomic fluorescence spectrometric detection for Hg. At Hg concentrations of 40 and 350 nmol/L, the within-day assay CVs were 5% and 3%, respectively; between-day assay CVs were 8% and 5%, respectively. Accuracy, as demonstrated by analytical recovery, ranged from 98% to 105%. The detection limit for the assay is 50 pmol/L, which is suitable for measuring total Hg concentrations in specimens of human urine, blood, and breast milk, and in monkey kidney cortex and feces, obtained from subjects with and without amalgam fillings.


1961 ◽  
Vol 201 (6) ◽  
pp. 1123-1125 ◽  
Author(s):  
David B. Gordon ◽  
Donald H. Hesse

It was found upon intravenous injection of adenosine and its mono-, di-, and triphosphate in the rat that ADP produced the greatest fall in arterial blood pressure. At low dose levels ADP was about 147 times as potent as adenosine and about 45 times as potent as AMP or ATP on an equimolar basis. The rat is more sensitive to the blood pressure lowering action of the adenosine compounds than other species thus far tested.


2008 ◽  
Vol 33 (1) ◽  
pp. 25-30 ◽  
Author(s):  
V. Muthuviveganandavel ◽  
P. Muthuraman ◽  
S. Muthu ◽  
K. Srikumar
Keyword(s):  
Low Dose ◽  

1999 ◽  
Vol 107 ◽  
pp. 639 ◽  
Author(s):  
Abraham Brouwer ◽  
Matthew P. Longnecker ◽  
Linda S. Birnbaum ◽  
Jim Cogliano ◽  
Paul Kostyniak ◽  
...  
Keyword(s):  
Low Dose ◽  

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