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15 result(s) for "BMDL"
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Guidance on the use of the benchmark dose approach in risk assessment
The Scientific Committee (SC) reconfirms that the benchmark dose (BMD) approach is a scientifically more advanced method compared to the no‐observed‐adverse‐effect‐level (NOAEL) approach for deriving a Reference Point (RP). The major change compared to the previous Guidance (EFSA SC, 2017) concerns the Section 2.5, in which a change from the frequentist to the Bayesian paradigm is recommended. In the former, uncertainty about the unknown parameters is measured by confidence and significance levels, interpreted and calibrated under hypothetical repetition, while probability distributions are attached to the unknown parameters in the Bayesian approach, and the notion of probability is extended to reflect uncertainty of knowledge. In addition, the Bayesian approach can mimic a learning process and reflects the accumulation of knowledge over time. Model averaging is again recommended as the preferred method for estimating the BMD and calculating its credible interval. The set of default models to be used for BMD analysis has been reviewed and amended so that there is now a single set of models for quantal and continuous data. The flow chart guiding the reader step‐by‐step when performing a BMD analysis has also been updated, and a chapter comparing the frequentist to the Bayesian paradigm inserted. Also, when using Bayesian BMD modelling, the lower bound (BMDL) is to be considered as potential RP, and the upper bound (BMDU) is needed for establishing the BMDU/BMDL ratio reflecting the uncertainty in the BMD estimate. This updated guidance does not call for a general re‐evaluation of previous assessments where the NOAEL approach or the BMD approach as described in the 2009 or 2017 Guidance was used, in particular when the exposure is clearly lower (e.g. more than one order of magnitude) than the health‐based guidance value. Finally, the SC firmly reiterates to reconsider test guidelines given the wide application of the BMD approach. This publication is linked to the following EFSA Supporting Publications article: http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2022.EN-7585/full
Update: use of the benchmark dose approach in risk assessment
The Scientific Committee (SC) reconfirms that the benchmark dose (BMD) approach is a scientifically more advanced method compared to the NOAEL approach for deriving a Reference Point (RP). Most of the modifications made to the SC guidance of 2009 concern the section providing guidance on how to apply the BMD approach. Model averaging is recommended as the preferred method for calculating the BMD confidence interval, while acknowledging that the respective tools are still under development and may not be easily accessible to all. Therefore, selecting or rejecting models is still considered as a suboptimal alternative. The set of default models to be used for BMD analysis has been reviewed, and the Akaike information criterion (AIC) has been introduced instead of the log‐likelihood to characterise the goodness of fit of different mathematical models to a dose–response data set. A flowchart has also been inserted in this update to guide the reader step‐by‐step when performing a BMD analysis, as well as a chapter on the distributional part of dose–response models and a template for reporting a BMD analysis in a complete and transparent manner. Finally, it is recommended to always report the BMD confidence interval rather than the value of the BMD. The lower bound (BMDL) is needed as a potential RP, and the upper bound (BMDU) is needed for establishing the BMDU/BMDL per ratio reflecting the uncertainty in the BMD estimate. This updated guidance does not call for a general re‐evaluation of previous assessments where the NOAEL approach or the BMD approach as described in the 2009 SC guidance was used, in particular when the exposure is clearly smaller (e.g. more than one order of magnitude) than the health‐based guidance value. Finally, the SC firmly reiterates to reconsider test guidelines given the expected wide application of the BMD approach. http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2017.EN-1147/full
Recommended approaches in the application of toxicogenomics to derive points of departure for chemical risk assessment
There is increasing interest in the use of quantitative transcriptomic data to determine benchmark dose (BMD) and estimate a point of departure (POD) for human health risk assessment. Although studies have shown that transcriptional PODs correlate with those derived from apical endpoint changes, there is no consensus on the process used to derive a transcriptional POD. Specifically, the subsets of informative genes that produce BMDs that best approximate the doses at which adverse apical effects occur have not been defined. To determine the best way to select predictive groups of genes, we used published microarray data from dose–response studies on six chemicals in rats exposed orally for 5, 14, 28, and 90 days. We evaluated eight approaches for selecting genes for POD derivation and three previously proposed approaches (the lowest pathway BMD, and the mean and median BMD of all genes). The relationship between transcriptional BMDs derived using these 11 approaches and PODs derived from apical data that might be used in chemical risk assessment was examined. Transcriptional BMD values for all 11 approaches were remarkably aligned with corresponding apical PODs, with the vast majority of toxicogenomics PODs being within tenfold of those derived from apical endpoints. We identified at least four approaches that produce BMDs that are effective estimates of apical PODs across multiple sampling time points. Our results support that a variety of approaches can be used to derive reproducible transcriptional PODs that are consistent with PODs produced from traditional methods for chemical risk assessment.
bmd : an R package for benchmark dose estimation
The benchmark dose (BMD) methodology is used to derive a hazard characterization measure for risk assessment in toxicology or ecotoxicology. The present paper’s objective is to introduce the R extension package bmd, which facilitates the estimation of BMD and the benchmark dose lower limit for a wide range of dose-response models via the popular package drc . It allows using the most current statistical methods for BMD estimation, including model averaging. The package bmd can be used for BMD estimation for binomial, continuous, and count data in a simple set up or from complex hierarchical designs and is introduced using four examples. While there are other stand-alone software solutions available to estimate BMDs, the package bmd facilitates easy estimation within the established and flexible statistical environment R . It allows the rapid implementation of available, novel, and future statistical methods and the integration of other statistical analyses.
The Validity of Benchmark Dose Limit Analysis for Estimating Permissible Accumulation of Cadmium
Cadmium (Cd) is a toxic metal pollutant that accumulates, especially in the proximal tubular epithelial cells of kidneys, where it causes tubular cell injury, cell death and a reduction in glomerular filtration rate (GFR). Diet is the main Cd exposure source in non-occupationally exposed and non-smoking populations. The present study aimed to evaluate the reliability of a tolerable Cd intake of 0.83 μg/kg body weight/day, and its corresponding toxicity threshold level of 5.24 μg/g creatinine. The PROAST software was used to calculate the lower 95% confidence bound of the benchmark dose (BMDL) values of Cd excretion (ECd) associated with injury to kidney tubular cells, a defective tubular reabsorption of filtered proteins, and a reduction in the estimated GFR (eGFR). Data were from 289 males and 445 females, mean age of 48.1 years of which 42.8% were smokers, while 31.7% had hypertension, and 9% had chronic kidney disease (CKD). The BMDL value of ECd associated with kidney tubular cell injury was 0.67 ng/L of filtrate in both men and women. Therefore, an environmental Cd exposure producing ECd of 0.67 ng/L filtrate could be considered as Cd accumulation levels below which renal effects are likely to be negligible. A reduction in eGFR and CKD may follow when ECd rises from 0.67 to 1 ng/L of filtrate. These adverse health effects occur at the body burdens lower than those associated with ECd of 5.24 µg/g creatinine, thereby arguing that current health-guiding values do not provide a sufficient health protection.
The Mobility and Distribution of Lead and Cadmium in the Ecosystems of Two Lakes in Poland and Their Effect on Humans and the Environment
The presence of lead (Pb) and cadmium (Cd) can have considerable effects on the environment and on humans. The present study examines their levels in two lakes with different trophic levels located in northwestern Poland; their concentrations were determined in water and the bottom sediments, in common reed and in the organs of pike, bream and roach. The work also evaluates Pb and Cd bioavailability in bottom sediments, their potential for biomagnification, their bioaccumulation in the food chain and risk to human consumers. Metal concentrations were determined by graphite furnace atomic absorption spectrometry (GFAAS). The geochemical fractions of the metals were isolated by sequential extraction. Both Pb and Cd demonstrated low bioavailability, with the carbonate fraction playing a key role in their bioconversion. The concentrations of Pb and Cd in some organs and tissue types of fish and reeds correlated with their levels in water and sediments. No biomagnification was observed between the studied fish species. Calculations based on BMDL, TWI and THQ concentrations found Pb and Cd levels in the edible parts of fish to be within permissible limits and not to pose any threat to consumer health.
Heavy Metals and the Occurrence of Ulcerative Dermal Necrosis (UDN) in Sea Trout from the RIVER REGA, Poland—Consumer Health Assessment
Various factors, including heavy metals, can make fish more susceptible to disease. This study investigated, inter alia, the relationship between Pb, Cd, and Hg contamination of the organs and muscles of sea trout from the river Rega (Poland) and the occurrence of UDN (ulcerative skin necrosis) symptoms. Moreover, the dietary risk of Pb, Cd, and Hg uptake from the muscles of healthy sea trout was assessed based on estimated daily intake (EDI), target hazard quotient (THQ), benchmark dose lower confidence limits (BMDL01 and BMDL10), and tolerable weekly intake (TWI). The metal concentrations varied, depending on the fish organs and the fish condition. A significantly higher amount of Pb was found in the gonads, gills, and muscles, Cd in the kidneys, and Hg in the muscles of sea trout with UDN symptoms. The lowest concentrations of Pb and Cd were detected in the muscles, and of Hg in the gonads. Dietary exposure to Pb, Cd, and Hg accounted for: 0.4% of BMDL01 and 1.0% of BMDL10, 0.56% of TWI, and 16.5% of TWI, respectively. THQs for each metal and the HI value for combined metals were below 1. The weakening of fish due to UDN-like disease probably increased the accumulation of Pb in the gonads, gills, and muscles, and of Cd in the kidneys, of the sea trout. As regards the maximum levels (MRLs), the muscles of healthy sea trout are safe for consumption. The risk assessment suggests no concern for the health of consumers.
The NOAEL Equivalent of Environmental Cadmium Exposure Associated with GFR Reduction and Chronic Kidney Disease
Cadmium (Cd) is a highly toxic metal pollutant present in virtually all food types. Health guidance values were established to safeguard against excessive dietary Cd exposure. The derivation of such health guidance figures has been shifted from the no-observed-adverse-effect level (NOAEL) to the lower 95% confidence bound of the benchmark dose (BMD), termed BMDL. Here, we used the PROAST software to calculate the BMDL figures for Cd excretion (ECd) associated with a reduction in the estimated glomerular filtration rate (eGFR), and an increased prevalence of chronic kidney disease (CKD), defined as eGFR ≤ 60 mL/min/1.73 m2. Data were from 1189 Thai subjects (493 males and 696 females) mean age of 43.2 years. The overall percentages of smokers, hypertension and CKD were 33.6%, 29.4% and 6.2%, respectively. The overall mean ECd normalized to the excretion of creatinine (Ecr) as ECd/Ecr was 0.64 µg/g creatinine. ECd/Ecr, age and body mass index (BMI) were independently associated with increased prevalence odds ratios (POR) for CKD. BMI figures ≥24 kg/m2 were associated with an increase in POR for CKD by 2.81-fold (p = 0.028). ECd/Ecr values of 0.38–2.49 µg/g creatinine were associated with an increase in POR for CKD risk by 6.2-fold (p = 0.001). The NOAEL equivalent figures of ECd/Ecr based on eGFR reduction in males, females and all subjects were 0.839, 0.849 and 0.828 µg/g creatinine, respectively. The BMDL/BMDU values of ECd/Ecr associated with a 10% increase in CKD prevalence were 2.77/5.06 µg/g creatinine. These data indicate that Cd-induced eGFR reduction occurs at relatively low body burdens and that the population health risk associated with ECd/Ecr of 2.77–5.06 µg/g creatinine was not negligible.
Opinion on the follow‐up of the re‐evaluation of sorbic acid (E200) and potassium sorbate (E202) as food additives
In this opinion, the EFSA Panel on Food Additives and Flavourings (FAF Panel) was requested by the European Commission to carry out a scientific evaluation of an extended one‐generation reproductive toxicity study (EOGRTS) to determine whether it would allow reconsideration of the temporary group acceptable daily intake (ADI) for sorbic acid (E 200) and potassium sorbate (E 202), established by the Panel on Food Additives and Nutrient Sources added to Food (ANS Panel) in 2015. From the EOGTRS, the FAF Panel identified a lower confidence limit of the benchmark dose (BMDL) of 1,110 mg sorbic acid/kg body weight (bw) per day. By applying a default uncertainty factor of 100, the Panel established a group ADI expressed as 11 mg sorbic acid/kg bw per day for sorbic acid (E 200) and its potassium salt (E 202). In addition, European Commission asked EFSA to review a report on the ‘Stability of sorbic acid (E 200) and its potassium salt (E 202) during food processing and storage’ provided by industry. No new information was provided in this report, and therefore, in this opinion, there was no re‐assessment of the EFSA ANS opinion conclusions from 2015 regarding the stability of sorbates in food.
Health Risk in a Geographic Area of Thailand with Endemic Cadmium Contamination: Focus on Albuminuria
An increased level of cadmium (Cd) in food crops, especially rice is concerning because rice is a staple food for over half of the world’s population. In some regions, rice contributes to more than 50% of the total Cd intake. Low environmental exposure to Cd has been linked to an increase in albumin excretion to 30 mg/g creatinine, termed albuminuria, and a progressive reduction in the estimated glomerular filtration rate (eGFR) to below 60 mL/min/1.73 m2, termed reduced eGFR. However, research into albuminuria in high exposure conditions is limited. Here, we applied benchmark dose (BMD) analysis to the relevant data recorded for the residents of a Cd contamination area and a low-exposure control area. We normalized the excretion rates of Cd (ECd) and albumin (Ealb) to creatinine clearance (Ccr) as ECd/Ccr and Ealb/Ccr to correct for differences among subjects in the number of surviving nephrons. For the first time, we defined the excretion levels of Cd associated with clinically relevant adverse kidney health outcomes. Ealb/Ccr varied directly with ECd/Ccr (β = 0.239, p < 0.001), and age (β = 0.203, p < 0.001), while normotension was associated with lower Ealb/Ccr (β = −0.106, p = 0.009). ECd/Ccr values between 16.5 and 35.5 ng/L of the filtrate were associated with a 10% prevalence of albuminuria, while the ECd/Ccr value of 59 ng/L of the filtrate was associated with a 10% prevalence of reduced eGFR. Thus, increased albumin excretion and eGFR reduction appeared to occur at low body burdens, and they should form toxicity endpoints suitable for the calculation of health risk due to the Cd contamination of food chains.