Benchmark dose (BMD) modeling is an important step in human health risk assessment and is used as the default approach to identify the point of departure for risk assessment. A probabilistic ...framework for dose-response assessment has been proposed and advocated by various institutions and organizations; therefore, a reliable tool is needed to provide distributional estimates for BMD and other important quantities in dose-response assessment.
We developed an online system for Bayesian BMD (BBMD) estimation and compared results from this software with U.S. Environmental Protection Agency's (EPA's) Benchmark Dose Software (BMDS).
The system is built on a Bayesian framework featuring the application of Markov chain Monte Carlo (MCMC) sampling for model parameter estimation and BMD calculation, which makes the BBMD system fundamentally different from the currently prevailing BMD software packages. In addition to estimating the traditional BMDs for dichotomous and continuous data, the developed system is also capable of computing model-averaged BMD estimates.
A total of 518 dichotomous and 108 continuous data sets extracted from the U.S. EPA's Integrated Risk Information System (IRIS) database (and similar databases) were used as testing data to compare the estimates from the BBMD and BMDS programs. The results suggest that the BBMD system may outperform the BMDS program in a number of aspects, including fewer failed BMD and BMDL calculations and estimates.
The BBMD system is a useful alternative tool for estimating BMD with additional functionalities for BMD analysis based on most recent research. Most importantly, the BBMD has the potential to incorporate prior information to make dose-response modeling more reliable and can provide distributional estimates for important quantities in dose-response assessment, which greatly facilitates the current trend for probabilistic risk assessment. https://doi.org/10.1289/EHP1289.
Bringing together the ideas of experts from around the world, this incisive text offers cutting-edge perspectives on the risk analysis and governance of genetically modified organisms (GMOs), ...supporting effective and informed decision-making in developing countries. Comprised of four comprehensive sections, this book covers: integrated risk analysis and decision making, giving an overview of the science involved and examining risk analysis methods that impact decision-making on the release of GMOs, particularly in developing countries; diversification of expertise involved in risk analysis and practical ways in which the lack of expertise in developing countries can be overcome; risk analysis based regulatory systems and how they can be undermined by power relationships and socio-political interests, as well as strategies for improving GMO policy development and regulatory decision-making; and case studies from developing countries providing lessons based on real-world experience that can inform our current thinking.
Regulating chemical mixtures is a complex scientific and policy task. The aim of this study was to investigate typical mixtures and their potential risks based on internal exposure levels in the ...European population. Based on human biomonitoring (HBM) data made available via the HBM4EU project, we derived generic mixtures representative of a median (P50) and a worst-case scenario (P95) for adults and children. We performed a mixture risk assessment based on HBM concentrations, health-based guidance values (HBGVs) as internal thresholds of concern, and the conservative assumption of concentration addition applied across different toxicological endpoints. Maximum cumulative ratios (MCRs) were calculated to characterize the mixture risk. The mixtures comprise 136 biomarkers for adults and 84 for children, although concentration levels could be quantified only for a fraction of these. Due to limited availability of HBGVs, the mixture risk was assessed for a subset of 20 substance-biomarker pairs for adults and 17 for children. The mixture hazard index ranged from 2.8 (P50, children) to 9.2 (P95, adults). Six to seven substances contributed to over 95% of the total risk. MCR values ranged between 2.6 and 5.5, which is in a similar range as in previous studies based on human external exposures assessments. The limited coverage of substances included in the calculations and the application of a hazard index across toxicological endpoints argue for caution in the interpretation of the results. Nonetheless the analyses of MCR and MAF
can help inform a possible mixture assessment factor (MAF) applicable to single substance risk assessment to account for exposure to unintentional mixtures.
An increased nitrate (NO
) concentration in groundwater has been a rising issue on a global scale in recent years. Different consumption mechanisms clearly illustrate the adverse effects on human ...health. The goal of this present study is to assess the natural and anthropogenic NO
concentrations in groundwater in a semi arid area of Rajasthan and its related risks to human health in the different groups of ages such as children, males, and females. We have found that most of the samples (n = 90) were influenced by anthropogenic activities. The background level of NO
had been estimated as 7.2 mg/L using a probabilistic approach. About 93% of nitrate samples exceeded the background limit, while 28% of the samples were beyond the permissible limit of 45 mg/L as per the BIS limits. The results show that the oral exposure of nitrate was very high as compare to dermal contact. With regard to the non-carcinogenic health risk, the total Hazard Index (HI
) values of groundwater nitrate were an average of 0.895 for males, 1.058 for females, and 1.214 for children. The nitrate health risk assessment shows that about 38%, 46%, and 49% of the samples constitute the non-carcinogenic health risk to males, females, and children, respectively. Children were found to be more prone to health risks due to the potential exposure to groundwater nitrate.
Between 1965 and 1987, the cesarean section rate in the United States rose precipitously—from 4.5 percent to 25 percent of births. By 2009, one in three births was by cesarean, a far higher number ...than the 5–10% rate that the World Health Organization suggests is optimal. While physicians largely avoided cesareans through the mid-twentieth century, by the early twenty-first century, cesarean section was the most commonly performed surgery in the country. Although the procedure can be life-saving, how—and why—did it become so ubiquitous?
Cesarean Section is the first book to chronicle this history. In exploring the creation of the complex social, cultural, economic, and medical factors leading to the surgery’s increase, Jacqueline H. Wolf describes obstetricians’ reliance on assorted medical technologies that weakened the skills they had traditionally employed to foster vaginal birth. She also reflects on an unsettling malpractice climate—prompted in part by a raft of dubious diagnoses—that helped to legitimize “defensive medicine,” and a health care system that ensured cesarean birth would be more lucrative than vaginal birth. In exaggerating the risks of vaginal birth, doctors and patients alike came to view cesareans as normal and, increasingly, as essential. Sweeping change in women’s lives beginning in the 1970s cemented this markedly different approach to childbirth.
Wolf examines the public health effects of a high cesarean rate and explains how the language of reproductive choice has been used to discourage debate about cesareans and the risks associated with the surgery. Drawing on data from nineteenth- and early twentieth-century obstetric logs to better represent the experience of cesarean surgery for women of all classes and races, as well as interviews with obstetricians who have performed cesareans and women who have given birth by cesarean, Cesarean Section is the definitive history of the use of this surgical procedure and its effects on women’s and children’s health in the United States.
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