The Frequency of Risk Factors for Cleft Lip and Palate in Mexico: A Systematic Review.

BACKGROUND: Cleft lip and palate is an anomaly that affects both women and men. It is considered to be among the most frequent congenital abnormalities and is related to modifications in chromosomal DNA and multiple genetic alterations. This anomaly can also be associated with various environmental factors, such as tobacco and alcohol consumption, medication use, and exposure to different environmental and industrial toxic substances. The objective of this study was to document the frequency of risk factors related to cleft lip and palate through a systematic review of Mexican studies. METHODS: In this systematic review, a bibliographic search was conducted following PRISMA guidelines in the databases Scielo, ScienceDirect, PubMed, and EBSCO. Keywords related to cleft lip and palate, epidemiology, and risk factors were used. In all, 3 independent reviewers (J.A.S.L., S.L.V., and N.M.F.) selected and evaluated a total of 17 articles included in this analysis, achieving a coefficient of κ = 0.84. RESULTS: The analysis revealed that the highest frequency of conducted studies was in the State of Mexico. The most common risk factors identified were environmental, pharmacological, consumption habits, and gynecological factors. CONCLUSIONS: Identifying the main risk factors for cleft lip and palate in the Mexican population will enable the implementation of preventive measures aimed at reducing exposure to these factors. Additionally, early intervention can improve the quality of life for individuals affected by this condition.

Properties and medical applications of the Euphorbiaceae family and their bioproducts: a patent review.

Euphorbiaceae is a family of dicotyledonous angiosperm plants that occur mainly in the tropics and produce a variety of secondary metabolites. Given the abundance of the Euphorbiaceae species and the diversity of substances they produce, this study aims to investigate paten documents concerning inventions and models involving the pharmacological use of these species, contributing to the study of their medicinal potential. The present review delves into patent documents in the Patentscope database, from the application of search criteria, such as "simple search" with the "Euphorbiaceae" keyword, limited to the front page, with stemming, without language limitation, from any patent office, and excluding non-patent literature (NPL). The selected patents were prevalently published in East Asian offices between 1998 and 2023, including 41 species of Euphorbiaceae of 19 genera, with 31 metabolites represented. The collected metabolites predominantly exhibited anti-tumoral (N = 21), anti-inflammatory (N = 10), antioxidant (N = 7), and anti-bacterial (N = 6) activities. Additionally, some substances have shown valid properties for treating non-communicable diseases (N = 8). The patents demonstrate the biotechnological potential of species from the Euphorbiaceae family, which are exceptionally satile regarding their applications in the health sector. However, the small number of patents that identify specific metabolites hinders a more thorough investigation of the activities of the products extracted from these species.

[Status of occupational exposure limits of air toxic substances in the GESTIS Substances Database].

Objective: In order to understand the current situation of air toxic substances without occupational exposure limits (OELs) in the workplace in the Germany GESTIS Substance Database, and to provide an effective reference for formulating OELs of corresponding toxic substances and improving health standards. Methods: From March 2022 to May 2023, based on the standard of GBZ 2.1-2019 Occupational Exposure Limits for Hazardous Agents in the Workplace-Part 1: Chemical Hazardous Agents, air toxic substances without OELs in the standard of GBZ/T 300.1-2017 Determination of Toxic Substances in Workplace Air-Part 1: General Principles were screened out, then corresponding OELs in other countrie/regions were queried through the Germany GESTIS Substance Database. Results: Among the 333 kinds (classes) of air toxic substances in 160 parts of GBZ/T 300.1-2017 standard, 48 kinds (classes) of air toxic substances were screened out and had not yet been formulated OELs in GBZ 2.1-2019 standard. By querying the Germany GESTIS Substance Database, it was found that among the 48 kinds (classes) of air toxic substances, 35 kinds (classes) of air toxic substances had both 8-hour occupational exposure limit and short-term occupational exposure limit, 4 kinds (classes) of air toxic substances had 8-hour occupational exposure limit but no short-term occupational exposure limit, 9 kinds (classes) of air toxic substances hadn't been retrieved any OELs. In addition, standard test methods of 7 kinds of air toxic substances hadn't been published in the present, including trimethylchlorosilane, trimethylbenzenes, cumene, chloroethane, chloropropane, dibromoethane and acetophenone. Conclusion: In the process of formulating or revising the standards of GBZ 2.1-2019 and GBZ/T 300, the latest published OELs in the Germany GESTIS Substance Database could be used as a reference basis.

Compound- and element-specific accumulation characteristics of persistent toxic substances and metals in sediments of the Yellow Sea.

This study investigated the large-scale distributions of persistent toxic substances (PTSs) and heavy metals in sediments of the Yellow Sea, collected from six transects between latitudes 32 and 37 degrees north (n = 35). Elevated concentrations of polychlorinated biphenyls (PCBs) were detected near the mainland, with a predominance of low-chlorinated congeners (di to tetra, ∼60%), indicative of atmospheric deposition. Analysis of traditional and emerging polycyclic aromatic hydrocarbons (t-PAHs and e-PAHs) revealed notable enrichment in the Central Yellow Sea Mud Zone (CYSM), attributing fossil fuel combustion as the significant source. Styrene oligomers and alkylphenols exhibited notable accumulation near the Han River Estuary in South Korea and the Yangtze River Estuary in China, respectively. The accumulation of heavy metals was predominantly observed in the CYSM, with element-specific distribution patterns. Cluster analysis revealed distinct distribution patterns for PTSs and metals, highlighting their source-dependent and grain size-dependent behaviors. In addition, the distribution and accumulation of PTSs tended to depend on their partitioning coefficients, such as the octanol-air partition coefficient (log KOA) and octanol-water partition coefficient (log KOW). This study offers valuable insights into the sources, transport, and fate of hazardous substances in the Yellow Sea, emphasizing the necessity for targeted environmental management strategies.

Chronological distribution and potential sources of persistent toxic substances in soils from the glacier foreland of Midtre Lovénbreen, Svalbard.

Despite its reputation as one of the cleanest regions globally, recent studies have identified the presence of various persistent toxic substances (PTSs) in the environmental matrices collected from Svalbard. This study investigated the chronological distribution and potential sources of 81 PTSs in soils from the glacier foreland of Midtre Lovénbreen. Soil samples (n = 45) were categorized by age based on exposure to the atmosphere due to glacier retreat in July 2014 into five age groups: 80-100 years (n = 7), 60-80 years (n = 12), 40-60 years (n = 16), 20-40 years (n = 7), and <20 years (n = 3). Concentrations of polychlorinated biphenyls (PCBs, n = 32) in soils varied with age, ranging from 0.29 to 0.74 ng g-1 dw. In addition, the concentrations of polycyclic aromatic hydrocarbons (PAHs, n = 28), perylene, and alkyl-PAHs (n = 20) in soils ranged from 21 to 80 ng g-1 dw, 2.9-62 ng g-1 dw, and 73-420 ng g-1 dw, respectively. The concentrations of PTSs were observed to be greater in older soils. Principal component analysis revealed that PCBs in soils originated from various product sources. Positive matrix factorization modeling estimated the association of PAHs in soils with potential origins, such as diesel emissions, petroleum and coal combustion, and coal. Potential sources of PAHs were mainly coal in younger soils and diesel emissions and petroleum combustion in older soils. Alkyl-PAH compositions in the soil were similar to those of bituminous coal, with a noteworthy degree of weathering observed in older soils. The accumulation rate and flux of PTSs in soils exhibited compound-specific patterns, reflecting factors such as long-range transport, fate, origin, and recent inputs. These findings can serve as baseline data for protecting and preserving polar environments.

Exploring the Impact of Nickel Exposure on Female Fertility.

Introduction Infertility affects an estimated 186 million individuals globally and is associated with numerous mental health issues. Trace elements are essential for reproductive health, yet the role of nickel in female fertility is not well understood. Previous research has shown conflicting evidence regarding nickel's impact on ovarian function and its potential to disrupt reproductive processes. Methods We utilized data from the National Health and Nutrition Examination Survey (NHANES) focusing on a cohort of 7,839 women, with an emphasis on 1,404 women aged 18 to 35. Logistic regression was employed to investigate the relationship between urinary nickel levels and fertility status, controlling for age, BMI, and race/ethnicity. Results The fertility analysis included 880 fertile and 106 infertile women, identifying age as a significant predictor of fertility status. Nickel exposure did not demonstrate a statistically significant association with fertility. The racial distribution within the groups showed a higher proportion of non-Hispanic White women in the fertile category and Mexican American women in the infertile group, although race was not a significant predictor in the regression model. Conclusions We found no significant relationship between nickel exposure and fertility status when adjusted for race, BMI, and age. Age was the only significant factor associated with fertility. These results highlight the complexity of the interplay between environmental exposures and reproductive health, suggesting that further research is necessary to elucidate the role of nickel and other trace elements in fertility.

An approach to the management of acute poisoning in emergency settings.

The impact of poisoning can differ significantly depending on the specific substance consumed. Identifying toxic substances in a patient is crucial to obtaining a thorough medical history. Frontline healthcare providers in the emergency department often handle patients presenting with poisoning. Their clinical presentation can vary depending on their dose, duration of exposure, and pre-existing medical conditions. Initially, poisoning management entails administering supportive care such as absorption and enhancing the elimination of poison with charcoal and antidote administration after identifying the poisoning substances. This article aims to provide a basic overview of the concepts involved in evaluating and managing these individuals.

Uncontrolled Post-Industrial Landfill-Source of Metals, Potential Toxic Compounds, Dust, and Pathogens in Environment-A Case Study.

The aim of this case study was the evaluation of the selected metals' concentration, potential toxic compound identification, cytotoxicity analysis, estimation of the airborne dust concentration, biodiversity, and number of microorganisms in the environment (leachate, soil, air) of the biggest uncontrolled post-industrial landfills in Poland. Based on the results obtained, preliminary solutions for the future management of post-industrial objects that have become an uncontrolled landfill were indicated. In the air, the PM1 fraction dominated, constituting 78.1-98.2% of the particulate matter. Bacterial counts were in the ranges of 9.33 × 101-3.21 × 103 CFU m-3 (air), 1.87 × 105-2.30 × 106 CFU mL-1 (leachates), and 8.33 × 104-2.69 × 106 CFU g-1 (soil). In the air, the predominant bacteria were Cellulosimicrobium and Stenotrophomonas. The predominant fungi were Mycosphaerella, Cladosporium, and Chalastospora. The main bacteria in the leachates and soils were Acinetobacter, Mortierella, Proteiniclasticum, Caloramator, and Shewanella. The main fungi in the leachates and soils were Lindtneria. Elevated concentrations of Pb, Zn, and Hg were detected. The soil showed the most pronounced cytotoxic potential, with rates of 36.55%, 63.08%, and 100% for the A-549, Caco-2, and A-549 cell lines. Nine compounds were identified which may be responsible for this cytotoxic effect, including 2,4,8-trimethylquinoline, benzo(f)quinoline, and 1-(m-tolyl)isoquinoline. The microbiome included bacteria and fungi potentially metabolizing toxic compounds and pathogenic species.

Bioretention Design Modifications Increase the Simulated Capture of Hydrophobic and Hydrophilic Trace Organic Compounds.

Stormwater rapidly moves trace organic contaminants (TrOCs) from the built environment to the aquatic environment. Bioretention cells reduce loadings of some TrOCs, but they struggle with hydrophilic compounds. Herein, we assessed the potential to enhance TrOC removal via changes in bioretention system design by simulating the fate of seven high-priority stormwater TrOCs (e.g., PFOA, 6PPD-quinone, PAHs) with log KOC values between -1.5 and 6.74 in a bioretention cell. We evaluated eight design and management interventions for three illustrative use cases representing a highway, a residential area, and an airport. We suggest two metrics of performance: mass advected to the sewer network, which poses an acute risk to aquatic ecosystems, and total mass advected from the system, which poses a longer-term risk for persistent compounds. The optimized designs for each use case reduced effluent loadings of all but the most polar compound (PFOA) to <5% of influent mass. Our results suggest that having the largest possible system area allowed bioretention systems to provide benefits during larger events, which improved performance for all compounds. To improve performance for the most hydrophilic TrOCs, an amendment like biochar was necessary; field-scale research is needed to confirm this result. Our results showed that changing the design of bioretention systems can allow them to effectively capture TrOCs with a wide range of physicochemical properties, protecting human health and aquatic species from chemical impacts.

Integrated assessment of the natural purification capacity of tidal flat for persistent toxic substances and heavy metals in contaminated sediments.

Natural purification of pollutants is highly recognized as regulating ecosystem services; however, the purification capacity of tidal flats remains largely unknown and/or unquantified. A 60-day mesocosm transplant experiment was conducted in situ to assess the purification capacity of natural tidal flats. We adopted the advanced sediment quality triad approach, monitoring 10 endpoints, including chemical reduction, toxicity changes, and community recoveries. The results indicated that contaminated sediments rapidly recovered over time, particularly > 50% within a day, then slowly recovered up to âˆ¼ 70% in a given period (60 days). A significant early reduction of parent pollutants was evidenced across all treatments, primarily due to active bacterial decomposition. Notably, the presence of benthic fauna and vegetated halophytes in the treatments significantly enhanced the purification of pollutants in both efficacy and efficiency. A forecast linear modeling further suggested additive effects of biota on the natural purification of tidal flats, reducing a full recovery time from 500 to 300 days. Overall, the triad approach with machine learning practices successfully demonstrated quantitative insight into the integrated assessment of natural purification.

Analyzing retraction responses of Tubifex tubifex (Oligochaeta: Naididae) colonies to copper treatments through a digital image analysis approach for developing early biological warning systems.

Biological monitoring and assessments are commonly used for sustainable ecosystem management. Oligochaetes are found in various freshwater ecosystems and have been used as indicators of water quality and for the biological assessment of aquatic ecosystems. Among aquatic oligochaetes, the sludge worm Tubifex tubifex (Oligochaeta, Naididae) is tolerant to organic pollution and has been used as a biomonitoring indicator of toxicity and organic pollution. In this study, we investigated the response of worm colonies to copper (CuSO4) treatments (0.01, 0.05, 0.1, 0.5, and 1.0 mg/L) in an observation cage (100 mL beaker) for 30 min. Using a digital image analysis approach, we measured the changes in the colony image area between pre- and post-copper treatment. After copper treatment, the colony image area tended to decrease, even at low copper concentrations. In addition, the colony areas did not recover to their original levels at high concentrations, although those at low concentrations did. Area decreased proportional to the logarithm of the copper concentration. Finally, our results present the possible use of the retraction responses of Tubifex tubifex colonies to chemical disturbances as early biological warning systems.

Sample preparation for suspect screening of persistent, mobile and toxic substances and their phase II metabolites in human urine by mixed-mode liquid chromatography.

Persistent, mobile and toxic substances have drawn attention nowadays due to their particular properties, but they are overlooked in human monitorization works, limiting the knowledge of the human exposome. In that sense, human urine is an interesting matrix since not only parent compounds are eliminated, but also their phase II metabolites that could act as biomarkers. In this work, 11 sample preparation procedures involving preconcentration were tested to ensure maximum analytical coverage in human urine using mixed-mode liquid chromatography coupled with high-resolution tandem mass spectrometry. The optimized procedure consisted of a combination of solid-phase extraction and salt-assisted liquid-liquid extraction and it was employed for suspect screening. Additionally, a non-discriminatory dilute-and-shoot approach was also evaluated. After evaluating the workflow in terms of limits of identification and type II errors (i.e., false negatives), a pooled urine sample was analysed. From a list of 1450 suspects and in-silico simulated 1568 phase II metabolites (i.e. sulphates, glucuronides, and glycines), 44 and 14 substances were annotated, respectively. Most of the screened suspects were diverse industrial chemicals, but biocides, natural products and pharmaceuticals were also detected. Lastly, the complementarity of the sample preparation procedures, columns, and analysis conditions was assessed. As a result, dilute-and-shoot and the Acclaim Trinity P1 column at pH = 3 (positive ionization) and pH = 7 (negative ionization) allowed the maximum coverage since almost 70 % of the total suspects could be screened using those conditions.

Quantitative prediction of the growth inhibition of various harmful chemicals by statistical analysis of delayed fluorescence decay curves obtained from the green alga Raphidocelis subcapitata.

The toxicity of chemical substances to algal growth is generally measured by the 72-96 h algal growth inhibition test. We have developed a method to assess the toxicity of chemicals in aquatic environments more quickly and simply than conventional testing methods by delayed fluorescence (DF), which reflects the photosynthetic capacity of algae. The DF method is based on a technique for evaluating the amount of change in the decay curve due to the effects of chemicals ([Formula: see text], DF inhibition). Various studies on DF have been reported; however, few reports have evaluated the decay curve of DF by approach using inductive modeling based on measurement data such as principal component analysis (PCA) and partial least squares regression analysis (PLS). Therefore, the purpose of this study is to examine methods for estimating the magnitude and type of toxicity of chemicals by means of a principal component model (PC model) and multiple regression model (MR model) derived from changes in the decay curves of DF of algae exposed to a wide range of 37 toxic substances that have an effect of clear magnitude on algal growth. The changes in the DF decay curves due to exposure the 37 toxic substances to algae were summarized in the PC model composed of eigenvectors and scores of four principal components. For validation of usefulness, a hierarchical cluster analysis (HCA) of the amount of change in four PC scores revealed that the growth inhibition rate was more influential than the chemical type. We also found the possibility of quantitatively predicting the growth inhibition of chemicals by MR model by the amount of change in the PC scores.

Effects of maternal toxic substance consumption during breastfeeding on lactic acid bacteria abundance and nutritional content.

Breast milk is widely recognized as the primary source of nourishment for newborns, making it an unparalleled and indispensable provider of essential nutrients, microbiological components, immunological factors, and energy content. To investigate this further, a cohort comprising 254 breastfeeding women participated in interviews, and milk samples were aseptically collected for subsequent analysis involving bromatological, microbiological, and clinical analysis. The investigation focused on the identification of specific microorganisms in breast milk and their susceptibility to the exposure of toxic substances and controlled medications. Notably, this study places particular emphasis on the significant decline in lactic acid bacteria observed in breast milk when influenced by substances such as cocaine, cannabis, crystal, and morphine. These detrimental agents have been found to adversely affect the growth of microorganisms within breast milk. On the contrary, the outcomes of this study indicate that the utilization of toxic substances does not exert a noteworthy impact on the nutritional quality of breast milk.

Exploring Pro-Inflammatory Immunological Mediators: Unraveling the Mechanisms of Neuroinflammation in Lysosomal Storage Diseases.

Lysosomal storage diseases are a group of rare and ultra-rare genetic disorders caused by defects in specific genes that result in the accumulation of toxic substances in the lysosome. This excess accumulation of such cellular materials stimulates the activation of immune and neurological cells, leading to neuroinflammation and neurodegeneration in the central and peripheral nervous systems. Examples of lysosomal storage diseases include Gaucher, Fabry, Tay-Sachs, Sandhoff, and Wolman diseases. These diseases are characterized by the accumulation of various substrates, such as glucosylceramide, globotriaosylceramide, ganglioside GM2, sphingomyelin, ceramide, and triglycerides, in the affected cells. The resulting pro-inflammatory environment leads to the generation of pro-inflammatory cytokines, chemokines, growth factors, and several components of complement cascades, which contribute to the progressive neurodegeneration seen in these diseases. In this study, we provide an overview of the genetic defects associated with lysosomal storage diseases and their impact on the induction of neuro-immune inflammation. By understanding the underlying mechanisms behind these diseases, we aim to provide new insights into potential biomarkers and therapeutic targets for monitoring and managing the severity of these diseases. In conclusion, lysosomal storage diseases present a complex challenge for patients and clinicians, but this study offers a comprehensive overview of the impact of these diseases on the central and peripheral nervous systems and provides a foundation for further research into potential treatments.

Integration of electronic waste management: a review of current global generation, health impact, and technologies for value recovery and its pertinent management technique.

The fast evolution of waste electrical and electronic equipment (WEEE) has developed into a prime environmental perturb in recent days. Today, electrical and electronic products merely become a needed part of people life's and professional lives. The whole process of e-waste contains an organized collection system, appropriate dismantling, and its treatment of recycling. The unparalleled hastening of e-waste and unceremonious discarding lead to an adverse impact on a country's development. Currently, challenges in e-waste have a lack of practical aid, poor structure, and insufficient economic support. Several legislations have been imposed which aim to enhance the handling of e-waste. Operative management of e-waste is now essential for the protective atmosphere and human beings as well. This article provides the systemic flow of the e-waste definition, global information, and generation of e-waste and composition of e-waste which were discussed. The study categorized the hazardous effect of e-waste on human beings, and the content analysis of e-waste in recent LCA applications was highlighted. Further different metal extraction and recovery techniques from e-waste have been reviewed. A few sets of current practices and some recommendations on a global scale level were provided. Finally, based on analysis, some approaches to e-waste was accomplished, and equitable environmental management was taken into account to identify the future outlook areas.

Unintentional poisoning from decanted toxic household chemicals.

BACKGROUND: Although poisonings due to a toxic substance being decanted into a secondary container are often reported to poison centers, we were unable to locate prior European data about their circumstances, incidence and consequences. We sought to describe the circumstances and outcomes of this behavior. MATERIALS AND METHOD: We conducted a prospective study of all poison exposures involving transfer to a secondary container reported to our poison center during a six month interval (January 1, 2021 through June 30, 2021). We called patients and clinicians for follow up the next day. We used a prepared questionnaire and added the responses to the national database for French poison centers. RESULTS: We identified and included 238 patients (104 male, 134 female) with a median age of 39 years [range 0-94 y]. Exposure was mainly oral (n = 221), the secondary container was mainly a water bottle (n = 173), toxic substances were essentially cleaning products (n = 63) or bleach (n = 48). Symptoms were gastrointestinal (vomiting, diarrhea, abdominal pain) (n = 143) or respiratory (cough, dyspnea, aspiration pneumonia) (n = 15). The World Health Organisation/International Programme on Chemical Safety/European Commission/European Association of Poison Centres and Clinical Toxicologists Poisoning Severity Score was none in 76 cases (31.9%), minor in 147 (61.8%), moderate in 12 (5%), and severe in three cases (1.3%). Products that led to severe poisoning contained either ammonium hydroxide or sodium hydroxide. Two of the patients required intensive care treatment. At the end of the follow-up, 235 patients fully recovered, and three patients had sequelae. CONCLUSIONS: The study illustrates the risk of toxic substance transfer. Water bottles were the secondary containers in most exposures to decanted substances. Most had minor or no effects, but nearly one-quarter were admitted to the hospital. The few severe exposures involved either ammonium hydroxide or sodium hydroxide.

Potential risk assessment and toxicological impacts of nano/micro-plastics on human health through food products.

The problem of environmental pollution with plastic is becoming more and more acute every year. Due to the low rate of decomposition of plastic, its particles get into food and harm the human body. This chapter focuses on the potential risks and toxicological effects of both nano and microplastics on human health. The main places of distribution of various toxicants along with the food chain have been established. The effects of some examples of the main sources of micro/nanoplastics on the human body are also emphasised. The processes of entry and accumulation of micro/nanoplastics are described, and the mechanism of accumulation that occurs inside the body is briefly explained. Potential toxic effects reported from studies on various organisms are highlighted as well.

Distributions and potential sources of polychlorinated biphenyls and polycyclic aromatic hydrocarbons in the glacimarine sediments of Arctic Svalbard.

Distribution and sources of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in the glacimarine sediments (35 sites) of Svalbard were investigated. PCBs (32 congeners), traditional PAHs (15 homologs), emerging PAHs (11 homologs), and alkylated PAHs (16 homologs) were widely distributed in the Svalbard sediments (ranges: below method detection limit to 20, 21 to 3600, 1.0 to 1400, and 31 to 15,000 ng g-1 dry weight, respectively). Compositional analysis indicated that PCBs mainly originated from combustion sources, with PAHs being strongly influenced by local sources. Positive matrix factorization analysis showed that PAHs were associated with vehicle and petroleum combustion, coal, and coal combustion. Coal-derived PAHs contributed significantly to the sediments of Van Mijenfjorden. Remnants of coal mining activity trapped in the permafrost appear to enter the coastal environments as ground ice melts. Consequently, PAHs are currently emerging as the most significant contributors to potential risks in the Svalbard ecosystems.

Addressing systemic problems with exposure assessments to protect the public's health.

BACKGROUND: Understanding, characterizing, and quantifying human exposures to environmental chemicals is critical to protect public health. Exposure assessments are key to determining risks to the general population and for specific subpopulations given that exposures differ between groups. Exposure data are also important for understanding where interventions, including public policies, should be targeted and the extent to which interventions have been successful. In this review, we aim to show how inadequacies in exposure assessments conducted by polluting industries or regulatory agencies have led to downplaying or disregarding exposure concerns raised by communities; that underestimates of exposure can lead regulatory agencies to conclude that unacceptable risks are, instead, acceptable, allowing pollutants to go unregulated; and that researchers, risk assessors, and policy makers need to better understand the issues that have affected exposure assessments and how appropriate use of exposure data can contribute to health-protective decisions. METHODS: We describe current approaches used by regulatory agencies to estimate human exposures to environmental chemicals, including approaches to address limitations in exposure data. We then illustrate how some exposure assessments have been used to reach flawed conclusions about environmental chemicals and make recommendations for improvements. RESULTS: Exposure data are important for communities, public health advocates, scientists, policy makers, and other groups to understand the extent of environmental exposures in diverse populations. We identify four areas where exposure assessments need to be improved due to systemic sources of error or uncertainty in exposure assessments and illustrate these areas with examples. These include: (1) an inability of regulatory agencies to keep pace with the increasing number of chemicals registered for use or assess their exposures, as well as complications added by use of 'confidential business information' which reduce available exposure data; (2) the failure to keep assessments up-to-date; (3) how inadequate assumptions about human behaviors and co-exposures contribute to underestimates of exposure; and (4) that insufficient models of toxicokinetics similarly affect exposure estimates. CONCLUSION: We identified key issues that impact capacity to conduct scientifically robust exposure assessments. These issues must be addressed with scientific or policy approaches to improve estimates of exposure and protect public health.