A Signal-to-Noise Crossover Dose as the Point of Departure for Health Risk Assessment
نویسندگان
چکیده
BACKGROUND The U.S. National Toxicology Program (NTP) cancer bioassay database provides an opportunity to compare both existing and new approaches to determining points of departure (PoDs) for establishing reference doses (RfDs). OBJECTIVES The aims of this study were a) to investigate the risk associated with the traditional PoD used in human health risk assessment [the no observed adverse effect level (NOAEL)]; b) to present a new approach based on the signal-to-noise crossover dose (SNCD); and c) to compare the SNCD and SNCD-based RfD with PoDs and RfDs based on the NOAEL and benchmark dose (BMD) approaches. METHODS The complete NTP database was used as the basis for these analyses, which were performed using the Hill model. We determined NOAELs and estimated corresponding extra risks. Lower 95% confidence bounds on the BMD (BMDLs) corresponding to extra risks of 1%, 5%, and 10% (BMDL01, BMDL05, and BMDL10, respectively) were also estimated. We introduce the SNCD as a new PoD, defined as the dose where the additional risk is equal to the "background noise" (the difference between the upper and lower bounds of the two-sided 90% confidence interval on absolute risk) or a specified fraction thereof. RESULTS The median risk at the NOAEL was approximately 10%, and the default uncertainty factor (UF = 100) was considered most applicable to the BMDL10. Therefore, we chose a target risk of 1/1,000 (0.1/100) to derive an SNCD-based RfD by linear extrapolation. At the median, this approach provided the same RfD as the BMDL10 divided by the default UF. CONCLUSIONS Under a standard BMD approach, the BMDL10 is considered to be the most appropriate PoD. The SNCD approach, which is based on the lowest dose at which the signal can be reliably detected, warrants further development as a PoD for human health risk assessment.
منابع مشابه
Adaptive-Filtering-Based Algorithm for Impulsive Noise Cancellation from ECG Signal
Suppression of noise and artifacts is a necessary step in biomedical data processing. Adaptive filtering is known as useful method to overcome this problem. Among various contaminants, there are some situations such as electrical activities of muscles contribute to impulsive noise. This paper deals with modeling real-life muscle noise with α-stable probability distribution and adaptive filterin...
متن کاملReliability and Validity Assessment of the Persian Version of the Noise Exposure Questionnaire (NEQ): An NIHL Predictor Tool
Background: Noise and noise-induced hearing loss (NIHL) are the most prevalent workplace problems. The best way to prevent NIHL is to monitor people's annual noise exposure (ANE) using tools, such as questionnaires. The present study aims to assess reliability of the Persian version of the Noise Exposure Questionnaire (NEQ) and NIHL scores among workers. Materials & Methods: This descriptive s...
متن کاملAnother Method for Defuzzification Based On Characterization of Fuzzy Numbers
Here we consider approaches to the ranking of fuzzy numbers based upon the idea of associating with a fuzzy number a scalar value, its signal/noise ratios, where the signal and the noise are defined as the middle-point and the spread of each $gamma$-cut of a fuzzy number, respectively. We use the value of a as the weight of the signal/noise ratio of each $gamma$-cut of a fuzzy number to calcula...
متن کاملSelf-Adaptive Morphological Filter for Noise Reduction of Partial Discharge Signals
Partial Discharge assessment in the insulation of high voltage equipment is one of the most popular approaches for prevention of the insulation breakdown. In the procedure of thisassessment, noise reduction of partial discharge signals to get the original PD signal for accurate evaluation is inevitable. This denoising process shall be carried out such a way that the main features of the p...
متن کامل