Site-Specific Assessments of Environmental Risk and Natural Resource Damage Based on Great Horned Owls

Selection of receptors is a key element of ecological risk and natural resource damage assessments. The great horned owl (Bubo virginianus; GHO) has advantages as a tertiary terrestrial receptor and integrated measure of exposure to chemical residues in a multiple-lines-of-evidence approach that includes elucidation of contaminant exposure by measured (tissue-based) and predicted (dietary) methodologies, and population-level measures of potential adverse effects (i.e., productivity, abundance). Methods described herein exploited attributes of GHO behavior, including its propensity to nest in artificial nesting platforms. This approach allowed better control of experimental conditions, minimized uncertainty in assessment endpoints, and maximized data utility for testing hypotheses. During 5 years, 54 GHO nests (14 active territories) along 38 km of river floodplain were monitored at the Kalamazoo River Superfund Site (Kalamazoo/Allegan Counties, Michigan). Concentrations of polychlorinated biphenyls (PCBs) and otho-, para-substituted isomers of dichlorodiphenyltrichloroethane (DDT), including DDD/DDE (Σ DDTs), were measured in 24 eggs and 16 samples of nestling blood plasma. Dietary PCB exposure was predicted by determining site-specific dietary composition and sampling and quantifying PCB concentrations in 171 prey items collected within active GHO territories. The convergence of exposure and effects assessments improved confidence in resulting predictions of minimal risk to resident GHO populations (Hazard Quotients ≤1.5). Repeated GHO use of nesting platforms minimized temporal and spatial variability.     

A Preliminary Risk Assessment of Human Exposure to Phycotoxins in Shellfish: A Review

Over the past few decades, phycotoxins, secondary metabolites produced by toxic phytoplankton, have seen an increase in their frequency, concentrations, and geographic distribution. As shellfish accumulate phycotoxins making them unfit for human consumption, they are considered as an important food safety issue. Thus, a consumer exposure assessment on phycotoxins is necessary. Exposure assessment requires two types of information: contamination and consumption data. Shellfish contamination data on major toxins encountered by at-risk populations (Domoic Acid group, Okadaic Acid group, and Saxitoxin group) have been reviewed. Consumption data have been reviewed for both general and potential high-consumer populations. Then, we undertook acute and chronic exposure assessments, combining available French contamination data and our own consumption data. Studies including exposure assessment were then reviewed. Lastly, risk characterization was undertaken. It can be concluded that both acute and chronic exposure to phycotoxins via shellfish consumption is a matter of concern, mainly for high consumers identified in this review (specific populations and shellfish harvesters). However, the results for risk characterization must be improved. There is a need for (i) toxicological data to establish a Tolerable Daily Intake; (ii) an assessment of consumption and contamination data, undertaken at the same time, so as to assess exposure.     

Effect of Precipitation Variability on Pollutant Concentrations in Soil: Implications for Exposure and Risk Assessments

Concentrations of toxic pollutants in surface soils must be predicted in order to assess exposures and risks that may arise from emissions at incinerators and other air pollution sources. At present, concentrations are predicted using deterministic models and time-averaged values of input parameters. This steady-state equilibrium approach does not address variability in the underlying transport and fate processes. This paper explores the variability of pollutant concentrations in surface soils that arises from precipitation, an intermittent process that governs wet deposition and leaching processes. Using long-term (45 to 50 years) historical records at 6 climato-logically diverse sites, concentrations predicted using the steady-state approach are compared to those predicted using a dynamic numerical model that simulates dry and wet deposition, leaching, and pollutant accumulation in the surface layer of soil using a daily time step. The models are compared for pollutants of low, medium, and high water solubility. Both models show that predictions depend strongly on the pollutant solubility and the precipitation pattern at the location. Average concentrations differed between locations by a factor of up to 4 due to precipitation patterns; the solubility of the pollutant had a much more pronounced effect. Both models produced similar long-term trends, for example, the duration of the period needed to achieve a quasi-steady-state pollutant concentration. However, for soluble pollutants, the dynamic model produced maximum 24-hr average concentrations that exceeded long-term averages by 4 to 8 times, and long-term predictions of the dynamic model exceeded predictions of the steady-state model by 1.9 to 3.6 times (depending on the site). These differences are caused by the steady-state assumption that deposition and leaching occur continuously. While the steady-state model can be used to estimate long-term trends of moderately to highly insoluble pollutants, the dynamic model should be used to predict short-term, maximum concentrations and both short- and long-term averages of soluble pollutants. Site-specific exposure and risk assessments should consider temporal variation and the use of a dynamic model if concentrations of soluble pollutants approach risk-based target levels.     

Use of Biomarkers in Oil Spill Risk Assessment in the Marine Environment

Numerous molecular, cellular, and physiological biomarkers have been used to assess the responses of marine animals to petroleum compounds. To be used in ecological risk assessment after an oil spill, a biomarker response needs to be linked to petroleum exposure and not strongly influenced by internal and external confounding factors. Biomarker responses to petroleum PAH, dominated by alklated two-and three-ringed aromatics, can be quite different than responses to pyrogenic PAH, dominated by four-and five-ringed aromatics. In many field sites there is a mixture of petrogenic and pyrogenic PAH, along with other contaminants, making it difficult to relate biomarker responses to a particular contaminant class. Biomarkers used to assess marine animal responses in the field include the cytochrome P450 system, heat stress protein, histopathology, and bile fluorescent compounds (FAC). Other biomarkers, including DNA/chromosomal damage and phase 2 enzymes, have been shown to respond after laboratory exposure, but more work needs to be done to demonstrate their usefulness in the field. One of the most useful biomarkers of petroleum exposure are the FAC responses in fish, which can be used to distinguish between petrogenic and pyrogenic PAH exposure. Few of the presently used biomarkers are linked to higher order biological effects, e.g. toxicity, reproductive failure.     

Oil Spill Response Risk Judgments,Decisions, and Mental Models: Findings from Surveying U.S. Stakeholders and Coastal Residents

This study applies a mental models survey approach to assess public thinking about oil spills and oil spill response. Based on prior interdisciplinary oil spill response research, the study first applies qualitative interview results and a response risk decision model to the design of a survey instrument. The decision model considers controlled burning, public health, and seafood safety. Surveying U.S. coastal residents (36,978 pairs of responses) through Google Insights identifies beliefs and gaps in understanding as well as related values and preferences about oil spills, and oil spill responses. A majority of respondents are concerned about economic impacts of major oil spills, and tend to see ocean ecosystems as fragile. They tend to see information about chemical dispersants as more important than ecological baseline information, and dispersants as toxic, persistent, and less effective than other response options. Although respondents regard laboratory studies as predictive of the effects of oil and of controlled burning, they are less confident that scientists agree on the toxicity and effectiveness of dispersants. The results illustrate opportunities to reframe discussions of oil spill response in terms of tradeoffs between response options, and new possibilities for assessing public opinions and beliefs during events.     

Assessing Risks to Sea Otters and the Exxon Valdez Oil Spill: New Scenarios,Attributable Risk,and Recovery

The Exxon Valdez oil spill occurred more than two decades ago, and the Prince William Sound ecosystem has essentially recovered. Nevertheless, discussion continues on whether or not localized effects persist on sea otters (Enhydra lutris) at northern Knight Island (NKI) and, if so, what are the associated attributable risks. A recent study estimated new rates of sea otter encounters with subsurface oil residues (SSOR) from the oil spill. We previously demonstrated that a potential pathway existed for exposures to polycyclic aromatic hydrocarbons (PAHs) and conducted a quantitative ecological risk assessment using an individual-based model that simulated this and other plausible exposure pathways. Here we quantitatively update the potential for this exposure pathway to constitute an ongoing risk to sea otters using the new estimates of SSOR encounters. Our conservative model predicted that the assimilated doses of PAHs to the 1-in-1000th most-exposed sea otters would remain 1–2 orders of magnitude below the chronic effects thresholds. We re-examine the baseline estimates, post-spill surveys, recovery status, and attributable risks for this subpopulation. We conclude that the new estimated frequencies of encountering SSOR do not constitute a plausible risk for sea otters at NKI and these sea otters have fully recovered from the oil spill.     

Exposure to Crystalline Silica Inhalation Among Construction Workers: A Probabilistic Risk Analysis

Crystalline silica and its presence in dust generated during various construction activities may pose a health hazard to construction workers. In this article, the occupational exposure to crystalline silica and the related long-term health (cancer and non-cancer) risks among construction workers from five different trades (activities) were evaluated using a probabilistic approach. The predicted 95th percentile of the excess lifetime cancer risk and hazard quotients for exposure to crystalline silica ranged from 4.5 × 10^?5 to 1.2 × 10^?4, and 15 to 37, respectively. The efficiency of the state-of-the-art technologies to reduce silica inhalation at construction sites are evaluated in the context of reduction in long-term health risks to the construction workers. The use of engineering controls and personal protective equipments to reduce the exposure to crystalline silica reduced the hazard quotient and excess lifetime cancer risk approximately by 65% and 78%, respectively. The sensitivity analyses showed that the exposure concentration of crystalline silica was the most significant parameter in both cancer and non-cancer risk estimates for the construction workers. The breathing rate, the exposure factor, and the daily shift hours also significantly contribute to the cancer and non-cancer risk estimates for the construction workers.     

Probability and Persistence of High Pollutant Concentrations in Soils: A Modeling Study and Implications for Exposure and Risk Assessment

Risk assessments for environmental pollutants have relied upon steady-state models that do not represent the variability of pollutant transport and fate processes, thus predictions are unlikely to reflect the true variability in pollutant concentrations. Such models cannot be used to estimate the probability, magnitude and duration of short- to intermediate-term and high-concentration events that might lead to adverse acute impacts. In this study, a numerical model is used to simulate pollutant accumulation in surface soils at six U.S. locations that result from atmospheric deposition and leaching. Historical (50 year) precipitation data drive the model. Model predictions are filtered and analyzed to identify high pollution events (exceeding specific concentration thresholds) and their occurrence probability and duration. Predicted concentrations at each site varied by a factor of 100 over time and by a factor of five among the six locations. The frequency and duration of high pollution events also differed by locations and concentration threshold. In general, larger thresholds lead to less frequent events and shorter durations. The proposed method allows estimates of the probability of occurrence and duration of high pollution events, providing information that complements the steady-state methods.     

Health Risk Assessment and Vapor Intrusion: A Review and Australian Perspective

Soil contamination by volatile hydrocarbons is of public health importance due to vapor intrusion and indoor inhalation exposures. These are assessed using measurement or predictive modeling and need to consider the key areas of subsurface partitioning and transport, dwelling ventilation, and receptor inhalation dosimetry. While subsurface partitioning and transport have been subject to intensive international investigation, limited consideration has been given to the latter. Building ventilation research has developed multi-zone airflow and contaminant dispersal models including AccuRate, an Australian model that examines natural ventilation modeling, roof and sub-floor ventilation, and identifies the importance of geometry and thermal factors on ventilation (the most sensitive variable) and indoor pollutant concentrations. Inhalation dosimetry has received recent attention due to concerns over child inhalation susceptibility and dose metrics. Research using coupled computational fluid dynamics (CFD) and physiologically based pharmaco-kinetic (PBPK) models has reported variance from previous animal models’ extrapolation while CFD modeling of transient lung vapor absorption suggests the significance of transient versus steady-state evaluation of volatiles absorption into tissue and blood. The transient nature of sub-surface fate and transport, ventilation, and inhalation uptake thus warrants integrated exploration and application in order to realize improvements in vapor intrusion assessments. These perspectives and Australian modeling initiatives are presented in this article.     

Issues in Exposure and Dose Assessment for Epidemiology and Risk Assessment

Epidemiologic studies have been effective in identifying human environmental and occupational hazards. However, most epidemiologic data has been difficult to use in quantitative risk assessments because of the vague specification of exposure and dose. Toxicologic animal studies have used applied doses (quantities administered, or exposures with fixed duration) and well characterized end points to determine effects. However, direct use of animal data in human risk assessment has been limited by uncertainties in the extrapolation. The applied dose paradigm of toxicology is not suited for cross species extrapolation, nor for use in epidemiology as a dose metric because of the complexity of human exposures. Physiologically based pharmacokinetic (PBPK) modeling can estimate the time course of tissue concentrations in humans, given an exposure-time profile, and it has been used for extrapolating findings from animals to humans. It is proposed that human PBPK modeling can be used in appropriately designed epidemiologic studies to estimate tissue concentrations. Secondly, tissue time courses can be used to form dose metrics based on the type and time course of adverse effects. These dose metrics will strengthen the determination of epidemiologic dose-response relationships by reducing misclassification. Findings from this approach can be readily integrated into quantitative risk assessment.     

Microbial Factors Rather Than Bioavailability Limit the Rate and Extent of PAH Biodegradation in Aged Crude Oil Contaminated Model Soils

The rate and extent of polynuclear aromatic hydrocarbons (PAH) biodegradation in a set of aged model soils that had been contaminated with crude oil at the high concentrations (i.e.,>20,000?mg/kg) normally found in the environment were measured in 90-week slurry bioremediation experiments. Soil properties such as organic matter content, mineral type, particle diameter, surface area, and porosity did not significantly influence the PAH biodegradation kinetics among the 10 different model soils. A comparison of aged and freshly spiked soils indicates that aging affects the biodegradation rate and extent only for higher-molecular-weight PAHs, while the effects of aging are insignificant for 4-ring PAHs and total PAHs. In all model soils with the exception of kaolinite clay, the rate of abiotic desorption was faster than the rate of biodegradation during the initial phase of bioremediation treatment, indicating that PAH biodegradation was limited by microbial factors. Similarly, any of the higher-molecular-weight PAHs that were still present after 90 weeks of treatment were released rapidly during abiotic desorption tests, which demonstrates that bioavailability limitations were not responsible for the recalcitrance of these hydrocarbons. Indeed, an analysis of microbial counts indicates that a severe reduction in hydrocarbon degrader populations may be responsible for the observed incomplete PAH biodegradation. Therefore, it can be concluded that the recalcitrance of PAHs during bioremediation is not necessarily due to bioavailability limitations and that these residual contaminants therefore might pose a greater risk to environmental receptors than previously thought.     

Remediation of Gulf War Oil Spill Contaminated Soil by a Subcritical Water Extraction Process: Oil Removal,Recovery, and Degradation

Due to the unique properties of subcritical water (marked change in water's dielectric constant and viscosity), the extraction by subcritical water offers a great opportunity to remediate soil contaminated with organic pollutants as an alternative and green remediation method. In this study, subcritical water extraction is proposed as an efficient remediation technique for the Gulf War oil spill contaminated soil. The subcritical water extraction experiment was carried out in a lab-scale continuous flow apparatus. The three major operating factors, temperature, time and water flow rate, were evaluated in terms of optimum removal efficiency. The results show that crude oil removal depended largely on water temperature, whereas an extraction run time higher than 1 h and a water flow rate higher than 1.5 mL/min marginally or negatively affected removal efficiency. During subcritical water treatment at 300°C for 1 h at a flow rate of 1.5 mL/min, removal efficiency was almost 95%. Under these operating conditions, the subcritical water treatment demonstrated a similar removal efficiency to those of organic solvents like acetone. In contrast, the efficiency of oil recovery decreased with an increase in extraction temperature, due to degradation by a water self-oxidizing agent. Several degradation products identified in the treated soil and in the effluent sample (which initially were absent in the contaminated soil) were oxygen-containing aromatic compounds, confirming the oxidation-degradation.     

An Integrated Case Study for Evaluating the Impacts of an Oil Refinery Effluent on Aquatic Biota in the Delaware River: Advanced Chemical Fingerprinting of PAHs

More than one thousand samples were collected and analyzed to evaluate the potential impact of Motiva's oil refinery effluent on the receiving water, sediment, and biota of the Delaware River. The data collected from these samples were used with advanced chemical fingerprinting of polycyclic aromatic hydrocarbons (PAHs) in Motiva's oil refinery effluent to differentiate Motiva-related PAHs in sediment and biota from other sources. The PAHs released from the refinery between 1999 and 2002 were dominated by petrogenic 4-ring PAHs. Specifically, the refinery signature exhibited relatively high levels of fluoranthenes/pyrenes with two (FP2) and three (FP3) alkyl groups and benz(a)anthracene/chrysenes with two (BC2), three (BC3), and four (BC4) alkyl groups. This PAH signature, attributed to accelerated degradation of low molecular weight PAHs in the Motiva wastewater treatment plant, exhibited little variability over time relative to the background patterns in the Delaware River. This distinctive feature of the Motiva effluent allowed the identification of this source in other samples. Water and sediment samples identified a range of PAH characteristics associated with the Delaware River urban background signature. These characteristics included varying levels of 2- to 3-ring PAHs (likely from weathered automotive fuel, marine fuel, or bilge tank discharges), pyrogenic 4- to 6-ring PAHs (from partially combusted organic material like soot), and perylene (diagenetic product of terrestrial plant decomposition). The Motiva hydrocarbon signature was only evident at moderate to low levels in selected near-field sampling stations for sediment, bivalves, and effluent/nearfield water. PAHs in the river sediments beyond the near-field area were consistently associated with samples containing the Delaware River urban background signature, and exhibited little to no effect from the Refinery.     

Assessment of Polycyclic Aromatic Hydrocarbons (PAH) and Heavy Metals in the Vicinity of an Oil Refinery in India

Petroleum products are one of the major sources of energy for industry and daily life. Growth of the petroleum industry and shipping of petroleum products has resulted in the pollution. Populations living in the vicinity of oil refinery waste sites may be at greater risk of potential exposure to polycyclic aromatic hydrocarbons (PAH) through inhalation, ingestion, and direct contact with contaminated media. PAH have often been found to coexist with environmental pollutants including heavy metals due to similar pollution sources. The levels and distribution patterns of Σ16 PAH (sum of the 16 PAH) and heavy metals (lead, copper, nickel, cobalt, and chromium) were determined in soil and sediment in the vicinity (5 km radius) of an oil refinery in India. Concentrations of Σ16 PAH in the soils and sediments were found to be 60.36 and 241.23 ppm, respectively. Higher amount of PAH in sediments as compared to soil is due to low water solubility of PAH, settled in the bottom of aquatic bodies. The levels of lead, copper, nickel, cobalt, and chromium (total) in soil were 12.52, 13.52, 18.78, 4.84, and 8.29 ppm, while the concentrations of these metals in sediments were 16.38, 47.88, 50.15, 7.07, and 13.25 ppm, respectively. Molecular diagnostics indices of PAH (Ratio of Phenanthrene/Anthracene, Fluranthene/Pyrene) calculated for soil and sediment samples indicate that the oil refinery environment is contaminated with PAH from petrogenic as well as pyrolytic origin and heavy vehicular traffic on the Agra- Delhi National highway. Sixteen PAH priority pollutants were detected in the United States in entire samples collected near oil refinery areas and concentrations of Σ16 PAH in soil was found to be 1.20 times higher than the threshold value for PAH in soil by ICRCL (Inter-Departmental Committee on the Redevelopment of Contaminated Land). This concentration could lead to disastrous consequences for the biotic and abiotic components of the ecosystem and may affect the soil quality, thus impairing plant growth and its bioaccumulation in food chain.     

Potential Dermal Exposure and Risk Assessment for Applicators of Chlorothalonil and Chlorpyrifos in Cucumber Greenhouses in China

Occupational exposure to pesticides has not been conducted in depth so far in China. The potential dermal exposure and risk assessment were conducted for applicators through application with a knapsack power sprayer in cucumber greenhouses. The spray suspension was prepared with 75% chlorothalonil WP and 48% chlorpyrifos EC. The dermal patch method was applied to assess the potential dermal exposure (PDE) of applicators during application. The average total PDE on the whole body of applicators during application of chlorothalonil and chlorpyrifos was 83.2 mL h^?1 and 85.1 mL h^?1, respectively. The most exposed part of the body was arms, especially the right arm. For risk assessment, the margin of safety (MOS) was calculated from the PDE. The MOS values were 0.1 and 0.2 for application of chlorothalonil and chlorpyrifos, respectively, both less than 1, which indicated low possibility of health risk.     

Probability Density Functions Describing 24-Hour Inhalation Rates for Use in Human Health Risk Assessments: An Update and Comparison

Inhalation rates are used for quantifying inhalation health risks. The time-activity-ventilation (TAV) approach has had longstanding acceptance for estimating inhalation rate (IR) as a time-weighted average across a number of activity levels comprising a typical day. Probability density functions (PDFs) describing 24-hour inhalation rates were updated in this study by incorporating supplemental minute volume (V _i ) and time-activity (t _i ) data published since the time of the previous study and by correlating V _i with metabolic equivalents (METs) for the physical activities at the time of measurement. The metabolic correlations are an improvement over the previous study because they enable interpolation to fill data gaps where V _i data are sparse or absent for certain age groups at specific levels of physical activity. The updated PDFs were developed using Monte Carlo simulation and can be described with log normal distributions. The updated PDFs were compared with IR distributions developed through two other approaches: the metabolic energy conversion (MEC) approach; and the doubly labeled water (DLW) approach. Compared to the previous TAV estimates, this study's PDFs suggest lower IR for toddlers and teenagers, higher IR for adults and seniors, and similar IR for infants and children.     

Bioaccessibility and other key parameters in assessing oral exposure to PAH-contaminated soils and dust: A critical review

Soil ingestion is an important pathway for human exposure to polycyclic aromatic hydrocarbon (PAH)-contaminated soils and dust for children (via ingesting hand residue) as well as for adults (via occupational exposure). An appropriate selection of exposure parameter values is essential for having an accurate risk assessment. This review addresses key parameters for estimating oral exposure to PAH-contaminated soils/dust, discusses their variability and uncertainty, and provides recommendations for value selection. Bioaccessibility (contaminant fraction solubilized in gastro-intestinal tract, available for entering bloodstream and reaching target organs) and soil ingestion rate are two key parameters for exposure assessment (usually characterized by large variability and/or uncertainty), followed by exposure frequency/duration and body weight.     

Employing Detection Controlled Models in Health and Environmental Risk Assessment: A Case in Offshore Oil Drilling

This study examines the determinants of health, safety, and environmental (HS&E) incidence and reporting behavior in Gulf of Mexico offshore drilling. One objective is to determine statistically significant variables that influence the probability of HS&E incidence and reporting. Incidence modeling employs standard qualitative response models with binary and ordered dependent variables, and a Poisson specification. A second objective is to examine the impact of imperfect reporting on inferences. Unlike previous studies, models allowing for the possibility of imperfect reporting are specified and estimated. The results of this analysis provide strong evidence to support the hypothesis that aspects of well complexity and site complexity increase the likelihood of HS&E incidents in drilling. Equally important is evidence rejecting the hypothesis that broader oil company attributes influence HS&E incidence. An analysis of reporting behavior provides mixed support for the hypothesis that well-known firms are more likely to report an incident than their more anonymous counterparts. There is weak evidence indicating differential reporting behavior between regulatory districts. Finally, the analysis provides consistent support for the conclusion that a 1996 policy change reduced HS&E incidence and increased HS&E reporting. The results of this research provide guidance to company managers and regulators on the factors driving HS&E incidence and reporting. Results also provide evidence that models of imperfect reporting can alter, in this case reverse, the interpretation of trends in reported incidents. These results can be used to support efficient resource allocation to prevention efforts, and inform regulatory policy.     

Fish and Fish Oil Intake in Relation to Risk of Asthma: A Systematic Review and Meta-Analysis

Although laboratory studies suggest that long-chain n-3 polyunsaturated fatty acids (LCn3PUFAs) may reduce risk of asthma, epidemiological data remain controversial and inconclusive. We quantitatively reviewed the epidemiological studies published through December 2012 in PubMed and EMBASE by using a fixed-effects or random-effects model. Eleven studies, comprised of 99,093 individuals (3,226 cases), were included in the final dataset. Of them, 7 studies examined associations between intake of fish or LCn3PUFA and risk of asthma: 4 studies in children (996 cases from 12,481 children) and 3 in adults (1,311 cases from 82,553 individuals). Two studies (69 cases from 276 infants) investigated LCn3PUFA levels in mothers’ milk, and two studies assessed maternal fish consumption (786 cases from 2,832 individuals) during lactation and/or plasma LCn3PUFA levels during pregnancy (64 cases from 951 infants) in relation to offspring’s asthma. The pooled relative risk of child asthma were 0.76 (95% CI, 0.61–0.94) for fish consumption and 0.71 (95% CI, 0.52–0.96) for LCn3PUFA intake. No statistically significant association was found in studies among adults. Epidemiological data to date indicate that fish or LCn3PUFA intake may be beneficial to prevent asthma in children. Further studies are needed to establish causal inference and to elucidate the potential mechanisms.     

Exposure to lead increases the risk of meningioma and brain cancer: A meta-analysis

ObjectiveTo analyze the relationship between environmental lead exposure and various types of brain tumors.MethodsSearch databases PubMed, Web of Science, Embase and Chinese National Knowledge Infrastructure (CNKI) as of July 1, 2019. Stata 15.0 software was used for analysis.ResultsIn the case control, lead exposure was associated with gliomas and meningiomas 0.82 (95 % CI: 0.69, 0.95) and 1.06 (95 % CI: 0.65, 1.46). In the cohort study, lead exposure was associated with brain cancer and meningiomas 1.07 (95 % CI: 0.95, 1.19) and 1.06 (95 % CI: 0.94, 1.17). The risk of childhood brain tumors associated with parental lead exposure was 1.17 (95 % CI: 0.99, 1.34).ConclusionsLead may be a risk factor for meningiomas and brain cancers. However, the glioma results suggest that lead may be a protective factor, which needs to be further studied.