Advancements in Life Cycle Human Exposure and Toxicity Characterization

Two-Stage Machine Learning-Based Approach to Predict Points of Departure for Human Noncancer and Developmental/Reproductive Effects

Chemical points of departure (PODs) for critical health effects are crucial for evaluating and managing human health risks and impacts from exposure. However, PODs are unavailable for most chemicals in commerce due to a lack of in vivo toxicity data. We therefore developed a two-stage machine learning (ML) framework to predict human-equivalent PODs for oral exposure to organic chemicals based on chemical structure. Utilizing ML-based predictions for structural/physical/chemical/toxicological properties from OPERA 2.9 as features (Stage 1), ML models using random forest regression were trained with human-equivalent PODs derived from in vivo data sets for general noncancer effects (n = 1,791) and reproductive/developmental effects (n = 2,228), with robust cross-validation for feature selection and estimating generalization errors (Stage 2). These two-stage models accurately predicted PODs for both effect categories with cross-validation-based root-mean-squared errors less than an order of magnitude. We then applied one or both models to 34,046 chemicals expected to be in the environment, revealing several thousand chemicals of moderate concern and several hundred chemicals of high concern for health effects at estimated median population exposure levels. Further application can expand by orders of magnitude the coverage of organic chemicals that can be evaluated for their human health risks and impacts.

Quantifying pesticide emissions for drift deposition in comparative risk and impact assessment

Estimating emissions of chemical pesticides used in agriculture is an essential component in evaluating the potential toxicity-related impacts on humans and ecosystems in various comparative risk and impact assessment frameworks, such as life cycle assessment, environmental footprinting, absolute environmental sustainability assessment, chemical substitution, and risk prioritization. Emissions related to drift deposition-usually derived from drift experiments-can reach non-target areas, and vary as a function of crop characteristics and application technique. We derive cumulative drift deposition fractions for a wide range of experimental drift functions for use in comparative and mass-balanced approaches. We clarify that cumulative drift deposition fractions require to integrate the underlying drift functions over the relevant deposition area and to correct for the ratio of deposition area to treated field area to arrive at overall mass deposited per unit mass of applied pesticide. Our results show that for most crops, drift deposition fractions from pesticide application are below 0.03 (i.e. 3% of applied mass), except for grapes and fruit trees, where drift fractions can reach 5% when using canon or air blast sprayers. Notably, aerial applications on soybeans can result in significantly higher drift deposition fractions, ranging from 20% to 60%. Additionally, varying the nozzle position can lead to a factor of five differences in pesticide deposition, and establishing buffer zones can effectively reduce drift deposition. To address remaining limitations in deriving cumulative drift deposition fractions, we discuss possible alternative modelling approaches. Our proposed approach can be implemented in different quantitative and comparative assessment frameworks that require emission estimates of agricultural pesticides, in support of reducing chemical pollution and related impacts on human health and the environment.

Measuring the environmental impacts of sewage sludge use in agriculture in comparison with the incineration alternative

This study compares two scenarios for sewage sludge treatment i.e., agricultural-land application (LA) and incineration (INC), in an Italian context (Pavia province, Po Valley). The study was realised within a regional project aiming to obtain useful data to better address future sludge management policies. To do so, an attributional Life Cycle Assessment (LCA) approach was chosen and the multi-functionality was addressed by using system expansion. Results indicated that the scenario INC had higher impacts than scenario LA for the categories linked to process inputs and to the direct emissions of incineration, such as Global warming potential (= + 60 %)., Stratospheric Ozone Depletion, Ozone Formation, Mineral Resource Scarcity and Fossil Resource Scarcity. System expansion i.e., the production of non-renewable fertilisers, played a large role (higher impacts) in the categories related to resource scarcity in the INC scenario. On the other hand, LA scenario showed higher impacts than INC for direct emissions due to fertilisation (Marine and Freshwater Eutrophication, and Particulate Matter). In conclusion, the use of sewage sludge in agriculture seemed to be competitive with the alternative of incineration but both sludge quality and emission reduction during sludge distribution in the field play an important role in the reduction of environmental impacts.

Generating environmental sampling and testing data for micro- and nanoplastics for use in life cycle impact assessment

Ongoing efforts focus on quantifying plastic pollution and describing and estimating the related magnitude of exposure and impacts on human and environmental health. Data gathered during such work usually follows a receptor perspective. However, Life Cycle Assessment (LCA) represents an emitter perspective. This study examines existing data gathering and reporting approaches for field and laboratory studies on micro- and nanoplastics (MNPs) exposure and effects relevant to LCA data inputs. The outcomes indicate that receptor perspective approaches do not typically provide suitable or sufficiently harmonised data. Improved design is needed in the sampling, testing and recording of results using harmonised, validated and comparable methods, with more comprehensive reporting of relevant data. We propose a three-level set of requirements for data recording and reporting to increase the potential for LCA studies and models to utilise data gathered in receptor-oriented studies. We show for which purpose such data can be used as inputs to LCA, particularly in life cycle impact assessment (LCIA) methods. Implementing these requirements will facilitate proper integration of the potential environmental impacts of plastic losses from human activity (e.g. litter) into LCA. Then, the impacts of plastic emissions can eventually be connected and compared with other environmental issues related to anthropogenic activities.

Ecotoxicity characterization of chemicals: Global recommendations and implementation in USEtox

Chemicals emitted to the environment affect ecosystem health from local to global scale, and reducing chemical impacts has become an important element of European and global sustainability efforts. The present work advances ecotoxicity characterization of chemicals in life cycle impact assessment by proposing recommendations resulting from international expert workshops and work conducted under the umbrella of the UNEP-SETAC Life Cycle Initiative in the GLAM project (Global guidance on environmental life cycle impact assessment indicators). We include specific recommendations for broadening the assessment scope through proposing to introduce additional environmental compartments beyond freshwater and related ecotoxicity indicators, as well as for adapting the ecotoxicity effect modelling approach to better reflect environmentally relevant exposure levels and including to a larger extent chronic test data. As result, we (1) propose a consistent mathematical framework for calculating freshwater ecotoxicity characterization factors and their underlying fate, exposure and effect parameters; (2) implement the framework into the USEtox scientific consensus model; (3) calculate characterization factors for chemicals reported in an inventory of a life cycle assessment case study on rice production and consumption; and (4) investigate the influence of effect data selection criteria on resulting indicator scores. Our results highlight the need for careful interpretation of life cycle assessment impact scores in light of robustness of underlying species sensitivity distributions. Next steps are to apply the recommended characterization framework in additional case studies, and to adapt it to soil, sediment and the marine environment. Our framework is applicable for evaluating chemicals in life cycle assessment, chemical and environmental footprinting, chemical substitution, risk screening, chemical prioritization, and comparison with environmental sustainability targets.

A review of plants formaldehyde metabolism: Implications for hazardous emissions and phytoremediation

The wide use of hazardous formaldehyde (CH₂O) in disinfections, adhesives and wood-based furniture leads to undesirable emissions to indoor environments. This is highly problematic as formaldehyde is a highly hazardous and toxic compound present in both liquid and gaseous form. The majority of gaseous and atmospheric formaldehyde derive from microbial and plant decomposition. However, plants also reversibly absorb formaldehyde released from for example indoor structural materials in such as furniture, thus offering beneficial phytoremediation properties. Here we provide the first comprehensive review of plant formaldehyde metabolism, physiology and remediation focusing on release and absorption including species-specific differences for maintaining indoor environmental air quality standards. Phytoremediation depends on rhizosphere, temperature, humidity and season and future indoor formaldehyde remediation therefore need to take these biological factors into account including the balance between emission and phytoremediation. This would pave the road for remediation of formaldehyde air pollution and improve planetary health through several of the UN Sustainable Development Goals.

Nanosafety: An Evolving Concept to Bring the Safest Possible Nanomaterials to Society and Environment

The use of nanomaterials has been increasing in recent times, and they are widely used in industries such as cosmetics, drugs, food, water treatment, and agriculture. The rapid development of new nanomaterials demands a set of approaches to evaluate the potential toxicity and risks related to them. In this regard, nanosafety has been using and adapting already existing methods (toxicological approach), but the unique characteristics of nanomaterials demand new approaches (nanotoxicology) to fully understand the potential toxicity, immunotoxicity, and (epi)genotoxicity. In addition, new technologies, such as organs-on-chips and sophisticated sensors, are under development and/or adaptation. All the information generated is used to develop new in silico approaches trying to predict the potential effects of newly developed materials. The overall evaluation of nanomaterials from their production to their final disposal chain is completed using the life cycle assessment (LCA), which is becoming an important element of nanosafety considering sustainability and environmental impact. In this review, we give an overview of all these elements of nanosafety.

Towards a more comprehensive life cycle assessment framework for assessing toxicity-related impacts for livestock products: The case of Danish pork

In life cycle assessments of livestock systems, toxicity-related impacts are not commonly considered or only specific aspects (such as pesticides, manufacturing of inputs) are assessed. In this context, the aim of this study was to define a framework for assessing toxicity-related impacts and to characterize human toxicity and freshwater ecotoxicity for a livestock product based on applying the state-of-the-art models PestLCI Consensus and USEtox. Furthermore, methodological gaps were discussed and ways forward were suggested. The case study focused on Danish pork production and the toxicity results were reported per kg 'meat' (the parts of pig used for human consumption) leaving the slaughterhouse. The assessment framework included the use of pesticides and heavy metals in feed production, the use of veterinary pharmaceuticals in pig production, and the manufacturing of inputs. The use of cleaning agents could not be assessed with the currently available methods. New characterization factors were calculated for 35 chemicals not available in USEtox. For Danish pork production, feed production was the main contributor to the analyzed toxicity impacts. The use of pesticides was the main driver for organic substances while heavy metal emissions related to the application of pig manure to fields were the hotspot for metal-based substances. The use of veterinary pharmaceuticals contributed only to freshwater ecotoxicity by 3%. PestLCI Consensus estimates were compared with different approaches. The impact of metabolites of pesticides and veterinary pharmaceuticals was assessed and discussed. Methodological gaps and research needs were identified regarding the assessment of pesticides, veterinary pharmaceuticals, metal-based substances, inorganic substances, and combined exposure to multiple chemicals. Better data related to the use and chemical properties of substances are needed to reduce uncertainty in toxicity modeling.

Preschool children health impacts from indoor exposure to PM2.5 and metals

To better understand the relation between children health and indoor air quality, we measured the concentrations of fine particulate matter (PM_2.5) and 11 metals (arsenic, cadmium, chromium, copper, iron, manganese, nickel, lead, antimony, selenium, and zinc) from air samples taken during both winter and spring, and focused on urban and rural area kindergartens of the Upper Silesia Region, Poland, typified by the use of fossil fuels for power and heat purposes. We combined related inhalation intake estimates for children and health effects using separate dose-response approaches for PM_2.5 and metals. Results show that impacts on children from exposure to PM_2.5 was 7.5 min/yr, corresponding to 14 μDALY/yr (DALY: disability-adjusted life years) with 95% confidence interval (CI): 0.3-164 min/yr, which is approximately 10 times lower than cumulative impacts from exposure to the metal components in the PM_2.5 fraction of indoor air (median 76 min/yr; CI: 0.2-4.5 × 10³ min/yr). Highest metal-related health impacts were caused by exposure to hexavalent chromium. The average combined cancer and non-cancer effects for hexavalent chromium were 55 min/yr, corresponding to 104 μDALY/yr, with CI: 0.5 to 8.0 × 10⁴ min/yr. Health impacts on children varied by season and across urban and rural sites, both as functions of varying PM_2.5 metal compositions influenced by indoor and outdoor emission sources. Our study demonstrates the need to consider indoor environments for evaluating health impacts of children, and can assist decision makers to focus on relevant impact reduction and indoor air quality improvement.

Estimating mouthing exposure to chemicals in children's products

BACKGROUND

Existing models for estimating children's exposure to chemicals through mouthing currently depends on the availability of chemical- and material-specific experimental migration rates, only covering a few dozen chemicals.

OBJECTIVE

This study objective is hence to develop a mouthing exposure model to predict migration into saliva, mouthing exposure, and related health risk from a wide range of chemical-material combinations in children's products.

METHODS

We collected experimental data on chemical migration from different products into saliva for multiple substance groups and materials, identifying chemical concentration and diffusion coefficient as main properties of influence. To predict migration rates into saliva, we adapted a previously developed migration model for chemicals in food packaging materials. We also developed a regression model based on identified chemical and material properties.

RESULTS

Our migration predictions correlate well with experimental data (R2 = 0.85) and vary widely from 8 × 10-7 to 32.7 µg/10 cm2/min, with plasticizers in PVC showing the highest values. Related mouthing exposure doses vary across chemicals and materials from a median of 0.005 to 253 µg/kgBW/d. Finally, we combined exposure estimates with toxicity information to yield hazard quotients and identify chemicals of concern for average and upper bound mouthing behavior scenarios.

SIGNIFICANCE

The proposed model can be applied for predicting migration rates for hundreds of chemical-material combinations to support high-throughput screening.

Exposure and Toxicity Characterization of Chemical Emissions and Chemicals in Products: Global Recommendations and Implementation in USEtox

PURPOSE

Reducing chemical pressure on human and environmental health is an integral part of the global sustainability agenda. Guidelines for deriving globally applicable, life cycle based indicators are required to consistently quantify toxicity impacts from chemical emissions as well as from chemicals in consumer products. In response, we elaborate the methodological framework and present recommendations for advancing near-field/far-field exposure and toxicity characterization, and for implementing these recommendations in the scientific consensus model USEtox.

METHODS

An expert taskforce was convened by the Life Cycle Initiative hosted by UN Environment to expand existing guidance for evaluating human toxicity impacts from exposure to chemical substances. This taskforce evaluated advances since the original release of USEtox. Based on these advances, the taskforce identified two major aspects that required refinement, namely integrating near-field and far-field exposure and improving human dose-response modeling. Dedicated efforts have led to a set of recommendations to address these aspects in an update of USEtox, while ensuring consistency with the boundary conditions for characterizing life cycle toxicity impacts and being aligned with recommendations from agencies that regulate chemical exposure. The proposed framework was finally tested in an illustrative rice production and consumption case study.

RESULTS AND DISCUSSION

On the exposure side, a matrix system is proposed and recommended to integrate far-field exposure from environmental emissions with near-field exposure from chemicals in various consumer product types. Consumer exposure is addressed via submodels for each product type to account for product characteristics and exposure settings. Case study results illustrate that product-use related exposure dominates overall life cycle exposure. On the effect side, a probabilistic dose-response approach combined with a decision tree for identifying reliable points of departure is proposed for non-cancer effects, following recent guidance from the World Health Organization. This approach allows for explicitly considering both uncertainty and human variability in effect factors. Factors reflecting disease severity are proposed to distinguish cancer from non-cancer effects, and within the latter discriminate reproductive/developmental and other non-cancer effects. All proposed aspects have been consistently implemented into the original USEtox framework.

CONCLUSIONS

The recommended methodological advancements address several key limitations in earlier approaches. Next steps are to test the new characterization framework in additional case studies and to close remaining research gaps. Our framework is applicable for evaluating chemical emissions and product-related exposure in life cycle assessment, chemical alternatives assessment and chemical substitution, consumer exposure and risk screening, and high-throughput chemical prioritization.

High Throughput Risk and Impact Screening of Chemicals in Consumer Products

The ubiquitous presence of more than 80,000 chemicals in thousands of consumer products used on a daily basis stresses the need for screening a broader set of chemicals than the traditional well-studied suspect chemicals. This high-throughput screening combines stochastic chemical-product usage with mass balance-based exposure models and toxicity data to prioritize risks associated with household products. We first characterize product usage using the stochastic SHEDS-HT model and chemical content in common household products from the CPDat database, the chemical amounts applied daily varying over more than six orders of magnitude, from mg to kg. We then estimate multi-pathways near- and far-field exposures for 5,500 chemical-product combinations, applying an extended USEtox model to calculate product intake fractions ranging from 0.001 to ∼1, and exposure doses varying over more than nine orders of magnitude. Combining exposure doses with chemical-specific dose-responses and reference doses shows that risks can be substantial for multiple home maintenance products, such as paints or paint strippers, for some home-applied pesticides, leave-on personal care products, and cleaning products. Sixty percent of the chemical-product combinations have hazard quotients exceeding 1, and 9% of the combinations have lifetime cancer risks exceeding 10^-4 . Population-level impacts of household products ingredients can be substantial, representing 5 to 100 minutes of healthy life lost per day, with users' exposures up to 10³ minutes per day. To address this issue, present mass balance-based models are already able to provide exposure estimates for both users and populations. This screening study shows large variations of up to 10 orders of magnitude in impact across both chemicals and product combinations, demonstrating that prioritization based on hazard only is not acceptable, since it would neglect orders of magnitude variations in both product usage and exposure that need to be quantified. To address this, the USEtox suite of mass balance-based models is already able to provide exposure estimates for thousands of product-chemical combinations for both users and populations. The present study calls for more scrutiny of most impacting chemical-product combinations, fully ensuring from a regulatory perspective consumer product safety for high-end users and using protective measures for users.

Integrating endocrine-related health effects into comparative human toxicity characterization

Endocrine-disrupting chemicals have the ability to interfere with and alter functions of the hormone system, leading to adverse effects on reproduction, growth and development. Despite growing concerns over their now ubiquitous presence in the environment, endocrine-related human health effects remain largely outside of comparative human toxicity characterization frameworks as applied for example in life cycle impact assessments. In this paper, we propose a new methodological framework to consistently integrate endocrine-related health effects into comparative human toxicity characterization. We present two quantitative and operational approaches for extrapolating towards a common point of departure from both in vivo and dosimetry-adjusted in vitro endocrine-related effect data and deriving effect factors as well as corresponding characterization factors for endocrine-active/endocrine-disrupting chemicals. Following the proposed approaches, we calculated effect factors for 323 chemicals, reflecting their endocrine potency, and related characterization factors for 157 chemicals, expressing their relative endocrine-related human toxicity potential. Developed effect and characterization factors are ready for use in the context of chemical prioritization and substitution as well as life cycle impact assessment and other comparative assessment frameworks. Endocrine-related effect factors were found comparable to existing effect factors for cancer and non-cancer effects, indicating that (1) the chemicals' endocrine potency is not necessarily higher or lower than other effect potencies and (2) using dosimetry-adjusted effect data to derive effect factors does not consistently overestimate the effect of potential endocrine disruptors. Calculated characterization factors span over 8-11 orders of magnitude for different substances and emission compartments and are dominated by the range in endocrine potencies.

Assessing Human Exposure to SVOCs in Materials, Products, and Articles: A Modular Mechanistic Framework

A critical review of the current state of knowledge of chemical emissions from indoor sources, partitioning among indoor compartments, and the ensuing indoor exposure leads to a proposal for a modular mechanistic framework for predicting human exposure to semivolatile organic compounds (SVOCs). Mechanistically consistent source emission categories include solid, soft, frequent contact, applied, sprayed, and high temperature sources. Environmental compartments are the gas phase, airborne particles, settled dust, indoor surfaces, and clothing. Identified research needs are the development of dynamic emission models for several of the source emission categories and of estimation strategies for critical model parameters. The modular structure of the framework facilitates subsequent inclusion of new knowledge, other chemical classes of indoor pollutants, and additional mechanistic processes relevant to human exposure indoors. The framework may serve as the foundation for developing an open-source community model to better support collaborative research and improve access for application by stakeholders. Combining exposure estimates derived using this framework with toxicity data for different end points and toxicokinetic mechanisms will accelerate chemical risk prioritization, advance effective chemical management decisions, and protect public health.

Chemicals of concern in plastic toys

We present a list of Chemicals of Concern (CoCs) in plastic toys. We started from available studies reporting chemical composition of toys to group plastic materials, as well as to gather mass fractions and function of chemicals in these materials. Chemical emissions from plastic toys and subsequent human exposures were then estimated using a series of models and a coupled near-field and far-field exposure assessment framework. Comparing human doses with reference doses shows high Hazard Quotients of up to 387 and cancer risk calculated using cancer slope factors of up to 0.0005. Plasticizers in soft plastic materials show the highest risk, with 31 out of the 126 chemicals identified as CoCs, with sum of Hazard Quotients >1 or child cancer risk >10^-6. Our results indicate that a relevant amount of chemicals used in plastic toy materials may pose a non-negligible health risk to children, calling for more refined investigations and more human- and eco-friendly alternatives. The 126 chemicals identified as CoCs were compared with other existing regulatory prioritization lists. While some of our chemicals appear in other lists, we also identified additional priority chemicals that are not yet covered elsewhere and thus require further attention. We finally derive for all considered chemicals the maximum Acceptable Chemical Content (ACC) in the grouped toy plastic materials as powerful green chemistry tool to check whether chemical alternatives could create substantial risks.

Building a European exposure science strategy

Exposure information is a critical element in various regulatory and non-regulatory frameworks in Europe and elsewhere. Exposure science supports to ensure safe environments, reduce human health risks, and foster a sustainable future. However, increasing diversity in regulations and the lack of a professional identity as exposure scientists currently hamper developing the field and uptake into European policy. In response, we discuss trends, and identify three key needs for advancing and harmonizing exposure science and its application in Europe. We provide overarching building blocks and define six long-term activities to address the identified key needs, and to iteratively improve guidelines, tools, data, and education. More specifically, we propose creating European networks to maximize synergies with adjacent fields and identify funding opportunities, building common exposure assessment approaches across regulations, providing tiered education and training programmes, developing an aligned and integrated exposure assessment framework, offering best practices guidance, and launching an exposure information exchange platform. Dedicated working groups will further specify these activities in a consistent action plan. Together, these elements form the foundation for establishing goals and an action roadmap for successfully developing and implementing a 'European Exposure Science Strategy' 2020-2030, which is aligned with advances in science and technology.

A biological characteristic extrapolation of compound toxicity for different developmental stage species with toxicokinetic-toxicodynamic model

Intraspecific difference in toxicity brings uncertainty to ecological risk assessment (ERA) and water quality criteria (WQC) of chemicals. Here, we compared intraspecies sensitivity to toxicants for Mesocyclops leuckarti of which toxicity data was obtained from published literatures, and zebrafish Danio rerio of which toxicity data was done in this study). Due to the internal concentration of chemicals not measured, simplified toxicokinetic-toxicodynamic (TK-TD) models were used, and we investigated whether TK-TD parameters estimated by Bayesian method might represent the differences in sensitivity between life-stages of 2 species. The results demonstrated that the difference in TK-TD parameters (background mortality m₀, no effect concentration NEC, the killing rate k_s, and the dominant rate k_d) could represent the toxicity difference between life-stages of individual species. The TK-TD model could predict toxicity in individual species (Cyprinus carpio L., Enchytraeus crypticus, Folsomia candida, Hyalella Azteca) exposed to different chemical concentrations and successfully extrapolate toxicity between different life stages of Mesocyclops leuckarti and Danio rerio by scaling several TK-TD parameters. The modified TK-TD model on the extrapolation toxicity of chemicals between life stages for species could be useful for the ERA and for deriving and revising WQC for chemicals.

Characterizing honey bee exposure and effects from pesticides for chemical prioritization and life cycle assessment

Agricultural pesticides are key contributors to pollinator decline worldwide. However, methods for quantifying impacts associated with pollinator exposure to pesticides are currently missing in comparative risk screening, chemical substitution and prioritization, and life cycle impact assessment methods. To address this gap, we developed a method for quantifying pesticide field exposure and ecotoxicity effects of honey bees as most economically important pollinator species worldwide. We defined bee intake and dermal contact fractions representing respectively oral and dermal exposure per unit mass applied, and tested our model on two pesticides applied to oilseed rape. Our results show that exposure varies between types of forager bees, with highest dermal contact fraction of 59 ppm in nectar foragers for lambda-cyhalothrin (insecticide), and highest oral intake fractions of 32 and 190 ppm in nectar foragers for boscalid (fungicide) and lambda-cyhalothrin, respectively. Hive oral exposure is up to 115 times higher than forager oral exposure. Combining exposure with effect estimates yields impacts, which are three orders of magnitude higher for the insecticide. Overall, nectar foragers are the most affected forager type for both pesticides, dominated by oral exposure. Our framework constitutes an important step toward integrating pollinator impacts in chemical substitution and life cycle impact assessment, and should be expanded to cover all relevant pesticide-crop combinations.

Estimate ecotoxicity characterization factors for chemicals in life cycle assessment using machine learning models

In life cycle assessment, characterization factors are used to convert the amount of the chemicals and other pollutants generated in a product's life cycle to the standard unit of an impact category, such as ecotoxicity. However, as a widely used impact assessment method, USEtox (version 2.11) only has ecotoxicity characterization factors for a small portion of chemicals due to the lack of laboratory experiment data. Here we develop machine learning models to estimate ecotoxicity hazardous concentrations 50% (HC₅₀) in USEtox to calculate characterization factors for chemicals based on their physical-chemical properties in EPA's CompTox Chemical Dashborad and the classification of their mode of action. The model is validated by ten randomly selected test sets that are not used for training. The results show that the random forest model has the best predictive performance. The average root mean squared error of the estimated HC₅₀ on the test sets is 0.761. The average coefficient of determination (R²) on the test set is 0.630, meaning 63% of the variability of HC₅₀ in USEtox can be explained by the predicted HC₅₀ from the random forest model. Our model outperforms a traditional quantitative structure-activity relationship (QSAR) model (ECOSAR) and linear regression models. We also provide estimates of missing ecotoxicity characterization factors for 552 chemicals in USEtox using the validated random forest model.

PM1 in Ambient and Indoor Air—Urban and Rural Areas in the Upper Silesian Region, Poland

(1) Background: The work presents results of concentration measurements of PM1, collected in the indoor air of four preschool buildings in Gliwice and its environs (Silesia Province) and in ambient air in the vicinity of four working hard coal power plants and four coking plants located in southern Poland. (2) Methods: The samples of <1 µm, 1–2.5 µm, 2.5–10 µm, and >10 µm fractions were collected with the use of Dekati® PM10 cascade impactor, and concentrations of seven trace elements (Cd, Cr, Mn, Ni, Pb, Sb, and Se) were determined. (3) Results: The concentrations of PM1 changed in the range of 3.1 μg/m3–65.3 μg/m3. Among trace elements, the highest concentrations in indoor air were evidenced for Cr (129–219 ng/m3), while in outdoor air for Pb (12.6–21.2 ng/m3). Principal Component Analysis PCA analysis extracted three factors of rural dusts, city dusts, and natural soils. (4) Conclusions: The paper points to accumulation of carcinogenic Cd, Cr, and Ni in indoor air, and significant contribution of trace elements in PM1, which, owing to long-lasting exposure and elevated sensitivity of developing organisms, may evoke effects on health of children.

Towards integrating toxicity characterization into environmental studies: case study of bromine in soils

AbstractPollution from bromine and some of its related compounds is currently unregulated in soil from Russia and other countries, and tools for sound assessment of environmental impacts of bromine contamination are largely missing. Hence, assessing potential implications for humans and ecosystems of bromine soil contamination is urgently needed, which requires the combination of measured soil concentrations from environmental studies and quantified potential toxicity impacts. To address this need, we used data from an experimental study assessing bromine in soils (384 samples) of Tomsk oblast, Russia, starting from measured concentrations obtained by Instrumental Neutron Activation Analysis in an earlier study. From these data, we calculated the bromine mass in soils and used these as starting point to characterize related cumulative impacts on human health and ecosystems in the Tomsk region, using a global scientific consensus model for screening-level comparative toxicity characterization of chemical emissions. Results show that the combination of sampling methodology with toxicity characterization techniques presents a new approach to be used in environmental studies aimed at environmental assessment and analysis of a territory. Our results indicate that it is important to account for substance-specific chemical reaction pathways and transfer processes, as well as to consider region-specific environmental characteristics. Our approach will help complement environmental assessment results with environmental sustainability elements, to consider potential tradeoffs in impacts, related to soil pollution, in support of improved emission and pollution reduction strategies.

Integrating exposure to chemicals in building materials during use stage

PURPOSE

There do not currently exist scientifically defensible ways to consistently characterize the human exposures (via various pathways) to near-field chemical emissions and associated health impacts during the use stage of building materials. The present paper thus intends to provide a roadmap which summarizes the current status and guides future development for integrating into LCA the chemical exposures and health impacts on various users of building materials, with a focus on building occupants.

METHODS

We first review potential human health impacts associated with the substances in building materials and the methods used to mitigate these impacts, also identifying several of the most important online data resources. A brief overview of the necessary steps for characterizing use stage chemical exposures and health impacts for building materials is then provided. Finally, we propose a systematic approach to integrate the use stage exposures and health impacts into building material LCA and describe its components, and then present a case study illustrating the application of the proposed approach to two representative chemicals: formaldehyde and methylene diphenyl diisocyanate (MDI) in particleboard products.

RESULTS AND DISCUSSION

Our proposed approach builds on the coupled near-field and far-field framework proposed by Fantke et al. (Environ Int 94:508-518, 2016), which is based on the product intake fraction (PiF) metric proposed by Jolliet et al. (Environ Sci Technol 49:8924-8931, 2015), The proposed approach consists of three major components: characterization of product usage and chemical content, human exposures, and toxicity, for which available methods and data sources are reviewed and research gaps are identified. The case study illustrates the difference in dominant exposure pathways between formaldehyde and MDI and also highlights the impact of timing and use duration (e.g., the initial 50 days of the use stage vs. the remaining 15 years) on the exposures and health impacts for the building occupants.

CONCLUSIONS

The proposed approach thus provides the methodological basis for integrating into LCA the human health impacts associated with chemical exposures during the use stage of building materials. Data and modeling gaps which currently prohibit the application of the proposed systematic approach are discussed, including the need for chemical composition data, exposure models, and toxicity data. Research areas that are not currently focused on are also discussed, such as worker exposures and complex materials. Finally, future directions for integrating the use stage impacts of building materials into decision making in a tiered approach are discussed.