Blood Lead Values Research Articles

Comparison of empirical and mechanistic blood lead models for children

Childhood exposure to lead can result in increased blood lead levels, which can have detrimental health effects. Models that can predict blood lead level based on exposure to floor and window sill dust lead at varying concentrations are useful tools for informing policy decisions. We compare an empirical model relating blood lead in children to the lead content of household dust, with a mechanistic model that simulates lead exposure in children through their daily activities. The empirical model is constructed using 1999–2004 NHANES data, while the mechanistic model is validated using 2011–2016 NHANES data. The models are evaluated at dust loadings ranging from 0.18 – 43 µg/ft2 and the resulting blood leads are compared. Specific demographic variables are chosen to simulate individuals are generated with “typical,” “high end,” and “low end” exposures in the empirical model; these are directly compared with the median, 95th, and 5th percentile results from the mechanistic model. For a child with “typical” lead exposure, the 95 % confidence interval for computed blood lead values contained the median blood lead value from the mechanistic model at all dust lead exposure levels considered. Similar results hold when comparing the 95th percentile to “high end” and 5th percentile to “low end”. The blood lead level computed by the mechanistic model increases more quickly with respect to dust loading than the empirical model, particularly at higher loadings. The empirical and mechanistic models generate similar blood lead distributions across the range of dust loadings considered, particularly at low loadings. The mechanistic model may be more appropriate for higher loadings due to limitations inherit in the structure of the empirical model.

Blood Lead Levels in the Population Living in Algeria: A Cross-Sectional National Study.

Lead poisoning, is currently recognized as a real public health problem, The WHO classifies lead as one of 10 chemicals of serious public health concern. In Algeria and North Africa, to date, no study on the evaluation of lead impregnation has been carried out at the national level. The main objective of this work is to assess the exposure of the general Algerian population to lead. A cross-sectional study was carried out over the entire Algerian national territory, on a population aged between 3 and 74years old. The survey lasted three years, A questionnaire, a clinical examination and a blood sample were carried out for each individual. Generalized linear regression models were used to determine the factors influencing lead levels measured in blood samples. The study population, spread over 39 wilayas and 121 districts, consists of 3674 individuals. The mean lead levels were 28.27μg/L, the median was 22.22μg/L, and the 95th percentile was 73.83μg/L, Blood lead levels were influenced differently by age, gender, wilaya of residence, dietary habits such as consumption of canned food and the way in which water is conserved for daily consumption. The use of kohl has been confirmed as a potential source of lead exposure. In Algeria, a blood lead value of 75µg/L serves as the Reference Exposure Value, guiding public health responses and risk management strategies, Recommendations have been issued to reduce the blood lead levels of the general population in Algeria in terms of limitation of lead in the sources of exposure, installation of an effective health monitoring system.

Biomonitoring of exposure of Algerian population to lead

Lead poisoning, is currently recognized as a real public health problem. The WHO classifies lead as one of 10 chemicals of serious public health concern. The assessment and management of health risks and public health interventions are largely based on a detailed knowledge of exposure of the general population. Biomonitoring has become an essential tool in environmental health. In Algeria, to date, no study on the evaluation of lead impregnation has been carried out at the national level. The main objective of this work is to assess the exposure of the general Algerian population to lead This is a cross-sectional study with a descriptive aim, carried out over the entire Algerian national territory, on a population aged between 3 and 74 years old. It was carried out on a representative sample of households. The survey lasted three years. A questionnaire, a clinical examination and a blood sample were carried out for each individual. Analytical methods for the determination of lead in whole blood by ICP-MS were optimized and validated. Generalized linear regression models were used to determine the factors influencing lead levels measured in blood samples. The study population, spread over 39 wilayas and 121 districts, consists of 3674 individuals. The mean lead levels were 28.27 μg/L [27.38–29.17], the median was 22.22 μg/L, and the 95th percentile was 73.83 μg/L. The prevalence of elevated blood lead levels (≥100 μg/L) in the study population was 2.2%. A blood lead value of 75 μg/L was proposed as the Reference Exposure Value (REL) for Algeria. Blood lead levels were influenced by age, gender, wilaya of residence, dietary habits such as consumption of canned food and the way in which water is conserved for daily consumption. The use of kohl has been confirmed as a potential source of lead exposure especially among women. Recommendations have been issued to reduce the blood lead levels of the general population in Algeria in terms of limitation of lead in the sources of exposure, installation of an effective health monitoring system and also an adequate management of lead poisoning.

Investigation on the effect of occupational lead exposure on bone mineral density of workers

Objective: To understand the occupational health status of a lead-acid battery enterprise in Jiangsu Province, to observe the results of blood lead and bone mineral density (BMD) of the workers exposed to occupational lead, and to explore the effect of occupational lead exposure on BMD, so as to provide basis for the prevention and treatment of occupational lead poisoning and osteoporosis. Methods: An occupational health survey was conducted in a lead-acid battery enterprise in Jiangsu Province in January 2019. Basic information and occupational health examination results of 402 persons exposed to occupational lead were collected, and BMD was measured. Spearman rank correlation test was used to analyze the relationship between blood lead and BMD, and logistic regression analysis was used to analyze the influencing factors of BMD. Results: The blood lead level M (P25, P75) of 402 occupational lead exposure workers was 220.5 (118.0, 307.0) μg/L, 46 workers (11.4%) had blood lead value ≥400 μg/L, and 5 workers (1.2%) ≥600 μg/L. 124 workers (30.8%) had abnormal BMD. The concentrations of lead dust and lead smoke in the workplace were <0.004-0.027 and <0.021-0.045 mg/m3, respectively. The positions exceeding the standard point were mainly concentrated in the casting and welding group (44.4%, 4/9) of lead smoke positions. There was a statistically significant difference in the overall distribution of blood lead levels among lead exposure workers with different BMD levels, and there was a positive correlation between blood lead and BMD (P<0.01) . The results of univariate analysis showed that there were statistically significant differences in the distribution of abnormal BMD among workers exposed to different genders, positions and blood lead levels (P<0.01) . The results of multivariate logistic regression analysis showed that the risk of abnormal BMD in male workers was 5.069 times of that in female worker (95%CI: 2.906-8.840, P<0.01) . Conclusion: Occupational lead exposure personnel have a high blood lead level and a high abnormal BMD rate. Exposure to lead working environment is an influencing factor for the abnormal BMD of workers, so enterprise managers should pay attention to health protection, occupational health monitoring and supervision of working environment of front-line workers.

Reduction in lead exposures with lead-free ammunition in an advanced urban assault course

The training of soldiers for urban conflict involves marksmanship instruction on outdoor flat ranges and the teaching of close-quarter battle techniques in indoor facilities, referred to as shoot houses, where intense firing exercises can generate high air lead levels from small arms ammunition, flash bang grenades, and explosive devices. Levels of lead and copper in air were evaluated during five training activities of a 45-day training course using both stationary general area and breathing zone sampling over a 2-year period. Individual blood lead values were determined prior to and at course completion. Mean breathing zone lead concentrations for the five training activities ranged from 0.014 on the outdoor flat range to 0.064 mg/m3 inside shoot houses; with a change to lead-free ammunition the values were reduced to a range of 0.006–0.022 mg/m3. Isolated flash bang grenades generated very high general area lead concentrations (2.0 mg/m3), which in training were associated with the highest measured breathing zone concentration (0.16 mg/m3). For copper, mean breathing zone concentrations increased from 0.010 to 0.037 mg/m3 with the change to lead-free frangible ammunition on the outdoor range, but remained below the permissible exposure limit for copper fume. Inside shoot houses, mean breathing zone copper concentrations exceeded the permissible exposure limit with ball and lead-free frangible ammunition, ranging from 0.077–0.13 mg/m3. With the introduction of lead-free ammunition, when comparing the blood lead differences between start and finish of the course, there was a significant reduction in the mean blood lead difference from 13.3 µg/dL to 5.4 µg/dL. Options for mitigation of potentially high exposure areas using improved ventilation designs are discussed. These results advocate for improved designs for shoot house training facilities, stress the importance of removing lead from ammunition and explosive devices for training, and promote the continued need for implementation of controls to mitigate and manage metal exposures during training.

Measurement Challenges at Low Blood Lead Levels.

In 2012, the Centers for Disease Control and Prevention (CDC) adopted its Advisory Committee on Childhood Lead Poisoning Prevention recommendation to use a population-based reference value to identify children and environments associated with lead hazards. The current reference value of 5 μg/dL is calculated as the 97.5th percentile of the distribution of blood lead levels (BLLs) in children 1 to 5 years old from 2007 to 2010 NHANES data. We calculated and updated selected percentiles, including the 97.5th percentile, by using NHANES 2011 to 2014 blood lead data and examined demographic characteristics of children whose blood lead was ≥90th percentile value. The 97.5th percentile BLL of 3.48 µg/dL highlighted analytical laboratory and clinical interpretation challenges of blood lead measurements ≤5 μg/dL. Review of 5 years of results for target blood lead values <11 µg/dL for US clinical laboratories participating in the CDC's voluntary Lead and Multi-Element Proficiency quality assurance program showed 40% unable to quantify and reported a nondetectable result at a target blood lead value of 1.48 µg/dL, compared with 5.5% at a target BLL of 4.60 µg/dL. We describe actions taken at the CDC's Environmental Health Laboratory in the National Center for Environmental Health, which measures blood lead for NHANES, to improve analytical accuracy and precision and to reduce external lead contamination during blood collection and analysis.

Peripubertal Blood Lead Levels and Male Adolescent Growth

Introduction: Lead exposure has been associated with reduced linear growth in children. Previously we reported associations of higher blood lead (BL) with lower height and serum IGF-1 in pubertal boys. We report the associations of peripubertal BL with adolescent growth in this cohort. Methods: 499 boys enrolled in 2003-2005 at ages 8-9 years were followed to 18 years in a prospective cohort study of environmental exposures, growth and sexual maturation. At study entry, 481 boys had BL measured, and guardians completed questionnaires on medical history, socioeconomic status (SES), and diet. Annual physical exams included height, weight, and pubertal stage assessment. Age-adjusted WHO height (HTZ) and body mass index (BMIZ) z-scores were calculated. Associations of BL (≥5 or <5 µg/dL) with longitudinal BMIZ and HTZ were examined by repeated measures linear regression. Results: The mean (SD) BL was 3.9 (2.8) µg/dL, and 28% of the boys had BL values ≥5 µg/dL. At age 18 years, 89% had achieved near adult heig...

Dose-Response Relationship between Cumulative Occupational Lead Exposure and the Associated Health Damages: A 20-Year Cohort Study of a Smelter in China.

Long-term airborne lead exposure, even below official occupational limits, has been found to cause lead poisoning at higher frequencies than expected, which suggests that China’s existing occupational exposure limits should be reexamined. A retrospective cohort study was conducted on 1832 smelting workers from 1988 to 2008 in China. These were individuals who entered the plant and came into continuous contact with lead at work for longer than 3 months. The dose-response relationship between occupational cumulative lead exposure and lead poisoning, abnormal blood lead, urinary lead and erythrocyte zinc protoporphyrin (ZPP) were analyzed and the benchmark dose lower bound confidence limits (BMDLs) were calculated. Statistically significant positive correlations were found between cumulative lead dust and lead fumes exposures and workplace seniority, blood lead, urinary lead and ZPP values. A dose-response relationship was observed between cumulative lead dust or lead fumes exposure and lead poisoning (p < 0.01). The BMDLs of the cumulative occupational lead dust and fumes doses were 0.68 mg-year/m3 and 0.30 mg-year/m3 for lead poisoning, respectively. The BMDLs of workplace airborne lead concentrations associated with lead poisoning were 0.02 mg/m3 and 0.01 mg/m3 for occupational exposure lead dust and lead fume, respectively. In conclusion, BMDLs for airborne lead were lower than occupational exposure limits, suggesting that the occupational lead exposure limits need re-examination and adjustment. Occupational cumulative exposure limits (OCELs) should be established to better prevent occupational lead poisoning.

Correlation of brain Magnetic Resonance Imaging of spontaneously lead poisoned bald eagles (Haliaeetus leucocephalus) with histological lesions: A pilot study

Six bald eagles with severe, acute lead poisoning based on blood lead values were analyzed by Magnetic Resonance Imaging (MRI) of the brain and histopathology. The aims of the study were to use MRI to locate brain lesions and correlate the changes in MRI signal with the histological character of the lesions at necropsy. All of the bald eagles presented with neurologic and non-neurologic signs suggestive of severe lead poisoning and had blood lead levels in excess of 1.0ppm. Areas of change in image intensity in the brainstem, midbrain and cerebellum were detected in the MRI scans. Histopathology confirmed the presence of all suspected lesions. The character of the lesions suggested vascular damage as the primary insult. MRI was useful for detecting lesions and defining their three-dimensional distribution and extent. Future studies are needed to evaluate the utility of MRI for detection of lesions in less severely lead poisoned eagles and determining prognosis for treatment.

Resistance to Lead of Streptococcus mutans Isolated from Adolescents in San Baltazar Tetela, Puebla

Aims: The purpose of this study was to determine if Streptococcus mutans have adapted to the polluted condition present among this population, adolescents 11-15 years of age with and without caries, and the resistance of this organism to grow at different concentrations of lead (Pb). Methodology: In Diagram 1. Summary of the different stages of experimental development are briefly explained in the following paragraphs. Results: The present investigation was made because contamination by chemical substances (heavy metals) represents an important health risk. We chose the community of San Baltazar Tetela, Puebla-Mexico as our study site since it experiences noticeable environmental contamination because of industrial emissions and run-off generated by the storage of these Original Research Article Martinez et al.; JSRR, 5(6): 446-467, 2015; Article no.JSRR.2015.112 447 polluting agents in the Manuel Avila Camacho dam (Valsequillo Lake). This study not only allowed us to quantify the concentration of lead in the blood of adolescents living in this community, but also to establish its possible association with socio-economic factors. On the other hand we isolated and identify Streptococcus mutans from saliva in teenagers. The mean blood lead value has a value of 7.89g/dL of blood (Graph. 3) in the lower levels to 10 g / dL, with lead levels greater 10g / dL of blood is 13. 18; not having statistically significant difference in applying the test, based on the weight and height of children with and without elevated lead, on the other hand the average value of CPO in children with normal blood lead was 3.99 (Graph.4), while children with higher lead levels to 10g / dL of blood, had a 7.41 CPO.

Environmental arsenic, cadmium and lead dust emissions from metal mine operations: Implications for environmental management, monitoring and human health

Although blood lead values in children are predominantly falling globally, there are locations where lead exposure remains a persistent problem. One such location is Broken Hill, Australia, where the percentage of blood lead values >10μg/dL in children aged 1–4 years has risen from 12.6% (2010), to 13% (2011) to 21% (2012). The purpose of this study was to determine the extent of metal contamination in places accessible to children. This study examines contemporary exposure risks from arsenic, cadmium, lead, silver and zinc in surface soil and dust, and in pre- and post-play hand wipes at six playgrounds across Broken Hill over a 5-day period in September 2013. Soil lead (mean 2,450mg/kg) and zinc (mean 3,710mg/kg) were the most elevated metals in playgrounds. Surface dust lead concentrations were consistently elevated (mean 27,500μg/m2) with the highest lead in surface dust (59,900μg/m2) and post-play hand wipes (60,900μg/m2) recorded close to existing mining operations. Surface and post-play hand wipe dust values exceeded national guidelines for lead and international benchmarks for arsenic, cadmium and lead. Lead isotopic compositions (206Pb/207Pb, 208Pb/207Pb) of surface dust wipes from the playgrounds revealed the source of lead contamination to be indistinct from the local Broken Hill ore body. The data suggest frequent, cumulative and ongoing mine-derived dust metal contamination poses a serious risk of harm to children.

Australia's leading public health body delays action on the revision of the public health goal for blood lead exposures

Globally, childhood blood lead levels have fallen precipitously in developed countries since the 1970s following action by international bodies such as the WHO and Food and Agricultural Organization (FAO) of the United Nations. These reductions have been affected by the activities of national agencies such as the US EPA and US Centers for Disease Control and Prevention in the establishment of air lead and blood lead standards, the introduction of legislation to remove lead from petrol, paint and consumer products and tighter restrictions on lead emissions. The outcome of recent major international reviews of research into the effects of low-level lead exposures (e.g. by WHO, USA health and environmental agencies, German and Canadian health bodies) has resulted in recommendations to reduce and eliminate lead exposures. By contrast, Australian policy responses to the incontrovertible evidence that adverse neurocognitive and behavioural effects that occur at levels well below the current national goal of 10μg/dL have stalled. The delayed response by Australia occurs at a time when blood lead levels in two of Australia's three primary lead mining and smelting cities: Port Pirie, South Australia and Broken Hill, New South Wales, are rising. In the third city, Mount Isa, Queensland, there is still no systematic, annual testing of childhood blood lead values. This is despite the fact that Mount Isa has the highest lead (and other toxic metals such as cadmium and arsenic) emissions to the environment (120tonnes of lead in 2011/12) from any single point source in Australia. It is clear that both state and national policy approaches to the ongoing risks of lead exposure need to be revised urgently and in line with contemporary international standards. Recommended changes should include a new lower blood lead intervention level of no more than 5μg/dL, with a national goal for all children under 5years of age to have a blood lead level of below 1μg/dL by 2020. In order to achieve any new lower exposure goals other relevant lead standards including air, dust, soil and water must also be revised downwards.

Correlation between total blood lead values and peripheral blood counts in workers occupationally exposed to urban stressors

The aim of the study was to assess the relationship between occupational exposure to airborne lead (Pb) and alterations in peripheral blood counts in workers of the Municipal Police assigned to different types of outdoor tasks. Then, 337 both male and female subjects were enrolled and divided on the basis of sex, cigarette smoking habit and kind of task. Exposure to airborne Pb, dosage of total blood Pb and peripheral blood count were carried out. A significant positive correlation was detected between the values of total blood Pb and values of plasma reticulocytes (%RET) both in the total sample and for all the classes of the subdivision except for police drivers. Some statistically significant correlations were present but discontinuous for other variables of peripheral blood counts. Results suggest that occupational exposure to low doses of airborne Pb is able to influence lines of the hematopoietic system in exposed workers, with special reference to %RET.

Practice-based evidence informs environmental health policy and regulation: A case study of residential lead‐soil contamination in Rhode Island

Prior to 1978, the exteriors of Rhode Island's municipal water towers were painted with lead-containing paint. Over time, this lead-containing paint either flaked-off or was mechanically removed and deposited on adjacent residential properties.Residents challenged inconsistencies across state agencies and federal requirements for collecting and analyzing soil samples.The purpose of this case study was to evaluate the efficacy of Rhode Island Department of Health (RIDOH) soil sampling regulations in determining the extent of lead contamination on residential properties using real world data.Researchers interviewed key government personnel, reviewed written accounts of events and regulations, and extracted and compiled lead data from environmental soil sampling on 31 residential properties adjacent to six municipal water towers. Data were available for 498 core samples.Approximately 26% of the residential properties had lead soil concentrations >1000mg/kg. Overall, lead concentration was inversely related to distance from the water tower. Analysis indicated that surface samples alone were insufficient to classify a property as “lead safe”. Potential for misclassification using RIDOH regulations was 13%. For properties deemed initially “lead free”, the total number of samples was too few to analyze. Post-remediation lead‐soil concentrations suggest the extent of lead contamination may have been deeper than initially determined. Additional data would improve the ability to draw more meaningful and generalized conclusions.Inconsistencies among regulatory agencies responsible for environmental health obfuscate transparency and erode the public's trust in the regulatory process. Recommendations for improvement include congruency across departmental regulations and specific modifications to lead‐soil sampling regulations reflective of lowered CDC reference blood lead value for children 1 to 5years old (5μg/dL). While scientific research informed the initial development of these environmental health policies and regulations, practice-based evidence did not support their efficacy in context of real world practice.

Variability and trend of multiple blood lead measures among construction and manufacturing workers

ObjectivesThis study evaluated multiple blood lead measures collected over time and assessed differences arising from exposure and testing variability.MethodsBlood lead data was used to compare individuals from manufacturing and construction...

Lead exposure among the general population of Duhok governorate, Kurdistan region, Iraq

This study was carried out to establish baseline data on lead exposure in a sample of the general population from Duhok governorate, Iraq in 2011. A cross-sectional study was made of blood lead levels of 820 individuals and of dust and of air lead levels in urban, suburban and rural residential areas. Mean blood lead (BPb) value in the overall sample was 7.3 (SD 2.8) microg/dL, range 1.6-17.0 microg/dL; significant differences were found with respect to age, area of residence, altitude and distance from a gasoline generator. The prevalence of toxic levels of lead (BPb >10 microg/dL) was 22.8% overall and 2.4% in children. People living in suburban areas (39.7%) and < 50 m from a gasoline generator (93.1%) were exposed to high environmental lead levels. A linear relationship was found between BPb and air lead levels (r = 0.8). While lead exposure does not constitute a great health problem for adults in our community, 2.4% of the children had toxic lead levels and measures to reduce exposure to environmental heavy metals should be considered.

Lead Poisoning Among Arab American and African American Children in the Detroit Metropolitan Area, Michigan

This study explored the hypothesis that acculturation is a risk factor for childhood lead poisoning in the Detroit area of Michigan. Blood lead levels (BLLs) were determined in 429 Arab American and African American children, aged 6 months to 15 years, who were receiving well-child examination in three Women, Infant, and Children (WIC) clinics in the city. Mean BLL was 3.8 ± 2.3 μg/dL (range: 1-18 μg/dL) and 3.3% of the children tested had blood lead values above the 10 μg/dL level of concern. Neither the age of the dwelling units nor ethnicity of the child was significantly associated with the BLL. Multivariable analyses instead identified a number of acculturation-related factors that are associated with elevation in blood lead including paternal education, language spoken at home (English only, English and Arabic, or Arabic only), home ownership, smoking in the home, and exposure of child to home health remedies. The difference in blood lead between Arab American children from families where Arabic only versus Arabic and English is spoken at home was found to be statistically significant. This study provides information showing that immigrant children are at heightened risk of being poisoned by lead which can be useful in identifying groups at risk of atypical exposures.

Determinants of maternal and umbilical blood lead levels: a cross-sectional study, Mosul, Iraq

BackgroundThe populations who are most sensitive to lead exposure from various sources are pregnant women and their newborns. Aiming to explore the presence of correlation between maternal and cord blood lead levels and to identify potential predictors that may influence both levels, the present study has been conducted.MethodsA cross-sectional study was conducted covering 350 full terms maternal-newborns pairs from Mosul maternity hospitals. Data were obtained directly from women just before delivery by the use of a detailed questionnaire form.Maternal and umbilical blood lead levels were estimated using LEADCARE® Blood Lead Testing System and Kits.ResultsA positive significant correlation was found between maternal and cord blood lead values (r = 0.856, p = 0.001). By backward stepwise logistic regression analysis the followings emerged as significant potential predictors of high maternal blood lead: low parity, smoking and Hb level <11 gm/dl. Regarding cord blood lead: coffee consumption and high maternal blood lead were significant risk predictors. Milk and milk products consumption, calcium intake and low level of physical activity were significantly operational in the prevention of high maternal blood lead levels. Iron intake and also low level of physical activity were shown as significant protective variables against high cord blood lead values.ConclusionStudy results have provided baseline data needed to be transformed to decision makers to implement measures to eliminate lead from the environment and protect future generation from its deleterious effects.

Windblown Lead Carbonate as the Main Source of Lead in Blood of Children from a Seaside Community: An Example of Local Birds as “Canaries in the Mine”

BackgroundIn late 2006, the seaside community in Esperance, Western Australia, was alerted to thousands of native bird species dying. The source of the lead was thought to derive from the handling of Pb carbonate concentrate from the Magellan mine through the port of Esperance, begun in July 2005. Concern was expressed for the impact of this process on the community.ObjectiveThis study was designed to evaluate the source of Pb in blood of a random sample of the community using Pb isotope ratios.MethodsThe cohort comprised 49 children (48 < 5 years of age) along with 18 adults (> 20 years of age) with a bias toward higher blood lead (PbB) values to facilitate source identification.ResultsMean PbB level of the children was 7.5 μg/dL (range, 1.5–25.7 μg/dL; n = 49; geometric mean, 6.6 μg/dL), with four children whose PbB was > 12 μg/dL. The isotopic data for blood samples lay around two distinct arrays. The blood of all children analyzed for Pb isotopes contained a contribution of Pb from the Magellan mine, which for young children ranged from 27% up to 93% (mean, 64%; median, 71%). Subtraction of the ore component gave a mean background PbB of 2.3 μg/dL. Several children whose PbB was > 9 μg/dL and most of the older subjects have complex sources of Pb.ConclusionsThe death of the birds acted as a sentinel event; otherwise, the exposure of the community, arising from such a toxic form of Pb, could have been tragic. Isotopic data and mineralogic and particle size analyses indicate that, apart from the recognized pathway of Pb exposure by hand-to-mouth activity in children, the inhalation pathway could have been a significant contributor to PbB for some of the very young children and in some parents.

Patients Prefer Pictures to Numbers to Express Cardiovascular Benefit From Treatment

This study aimed to determine which methods of expressing a preventive medication's benefit encourage patients with known cardiovascular disease to decide to take the medication and which methods patients prefer. We identified patients in Auckland, New Zealand, family practices located in areas of differing socioeconomic status who had preexisting heart disease (myocardial infarction, angina, or both) and were taking statins. The patients were interviewed about their preference for methods of expressing the benefit of a hypothetical medication. Benefits were expressed numerically (relative risk, absolute risk, number needed to treat, odds ratio, natural frequency) and graphically. Statistical testing was adjusted for practice. We interviewed 100 eligible patients, representing a 53% response rate. No matter how the risk was expressed, the majority of patients indicated they would be encouraged to take the medication. Two-thirds (68) of the patients preferred 1 method of expressing benefit over others. Of this group, 57% preferred the information presented graphically. This value was significantly greater (P <.001) than the 19% who chose the next most preferred option, relative risk. Few patients preferred absolute risk (13%) or natural frequencies (9%). Only a single patient (1%) preferred the odds ratio. None preferred number needed to treat. Ninety percent of patients responding to a question about framing preferred positive framing (description of the benefit of treatment) over negative framing (description of the harm of not being treated). Although number needed to treat is a useful tool for communicating risk and benefit to clinicians, this format was the least likely to encourage patients to take medication. As graphical representation of benefit was the method patients preferred most, consideration should be given to developing visual aids to support shared clinical decision making.