Evaluating chemical and other agent exposures for reproductive and developmental toxicity

Predicting zebrafish (Danio rerio) embryo developmental toxicity through a non-conformational QSAR approach

For many years, the frequent use of synthetic chemicals in the manufacture of veterinary drugs and plague control products has raised negative effects on human health and other non-target organisms, promoting the need to employ a practical and suitable methodology for early risk identification of several thousand commercial compounds. The zebrafish (Danio rerio) embryo has been emerged as one sustainable animal model for measuring developmental toxicity, an endpoint that is included in the regulatory procedures to approve chemicals, avoiding conventional and costly toxicity assays based on animal testing. In this context, the Quantitative Structure-Activity Relationships (QSAR) theory is applied to develop a predictive model based on a well-defined zebrafish embryo developmental toxicity database reported by the ToxCast™ Phase I chemical library of the Environmental Protection Agency (U.S. EPA). By means of four freely available softwares, a set with 28,038 non-conformational descriptors that encode the largest amount of permanent structural features are readily calculated. The Replacement Method (RM) variable subset selection technique provided the best regression models. Thereby, a linear QSAR model with proper statistical quality (R_train² = 0.64, RMSE_train = 0.49) is established in agreement with the Organization for Economic Co-operation and Development principles, accomplishing each internal (loo, l15 % o, VIF and Y-randomization) and external (R_test²,R_m², Q_F1², Q_F2², Q_F3² and CCC) validation criterion. The present QSAR approach provides a useful computational tool to estimate zebrafish developmental toxicity of new, untasted or hypothetical compounds, and it can contribute to the general lack of QSAR models in the literature to predict this endpoint.

A Scoping Review of Pregnancy, Childbirth, and the Postpartum Period in Active Duty U.S. Military Women

PURPOSE

Women in the U.S. military encounter unique challenges during the perinatal period that are driven by military requirements for mission readiness. The purpose of this scoping review was to systematically examine the extent, range, and nature of the literature on pregnancy, childbirth, and the postpartum period of active duty military women. A secondary aim was to identify leverage points for changes to improve perinatal health of servicewomen.

METHODS

We used a PRISMA-ScR protocol to guide this scoping review of research and non-research articles germane to the perinatal health of servicewomen. In the protocol, we identified the rationale, objectives, eligibility criteria, search strategy, sources of evidence, and data charting processes for the review. We used the social ecological model for military women's health framework to guide the synthesis of results.

FINDINGS

Eighty-four articles on the topics of pregnancy, childbirth, and the postpartum period of servicewomen published from 2000 to 2018 were identified. The articles were mainly research studies (n = 76), of which 49 had observational designs. Leverage points to promote workplace safety and support of pregnant women, perinatal screening, recognition of pregnancy and postpartum depression, and maintaining physical fitness during pregnancy and the postpartum period were identified in multiple levels of the social ecological model for military women's health.

CONCLUSIONS

Literature published from 2000 to 2018 is broad in scope, yet generally lacks a robust body of evidence on any one topic. Implementing strategies and military policies that are directed at the identified leverage points could enhance the health of childbearing servicewomen.

Development of novel in silico model for developmental toxicity assessment by using naïve Bayes classifier method

Toxicological testing associated with developmental toxicity endpoints are very expensive, time consuming and labor intensive. Thus, developing alternative approaches for developmental toxicity testing is an important and urgent task in the drug development filed. In this investigation, the naïve Bayes classifier was applied to develop a novel prediction model for developmental toxicity. The established prediction model was evaluated by the internal 5-fold cross validation and external test set. The overall prediction results for the internal 5-fold cross validation of the training set and external test set were 96.6% and 82.8%, respectively. In addition, four simple descriptors and some representative substructures of developmental toxicants were identified. Thus, we hope the established in silico prediction model could be used as alternative method for toxicological assessment. And these obtained molecular information could afford a deeper understanding on the developmental toxicants, and provide guidance for medicinal chemists working in drug discovery and lead optimization.

An overview of environmental hazards and exposure risk of hydrofluorocarbons (HFCs)

Hydrofluorocarbons (HFCs) are being used as replacements for chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) that cause significantly stratospheric ozone depletion and global warming. HFCs under commercial uses as cleaning solvents in the electronic components, blowing agent in the foamed plastics, refrigerant in the air conditioning units and refrigerators, fire suppression agent in the fire protection, propellant in the metered dose inhalers (MDIs), and dry etching agent in the semiconductor manufacturing. Among these HFCs, 1,1,1,2-tetrafluoroethane (HFC-134a) is the most widely used one. From the environmental, ecological, and health points of view, it is urgent to mitigate and control the emissions of these HFCs from a diversity of commercial applications and industrial processes. This article aims to introduce these HFCs in commercial uses and environmental hazards (i.e., global warming, photochemical potential, flammability safety, environmental partition and ecotoxicity). Further, the updated data on the human toxicity, occupational exposure and health risk of these HFCs (esp., HFC-134a) are addressed in this review paper.