Recommendations for medical management of adult lead exposure

Occupational exposure to airborne lead in Brazilian police officers

Shooting with lead-containing ammunition in indoor firing ranges is a known source of lead exposure in adults. Police officers may be at risk of lead intoxication when regular training shooting exercises are yearly mandatory to law enforcement officers. Effects on health must be documented, even when low-level elemental (inorganic) lead exposure is detected. Forty police officers (nineteen cadets and twenty-one instructors) responded to a questionnaire about health, shooting habits, and potential lead exposure before a training curse. Blood samples were collected and analyzed for blood lead level (BLL) before and after a three days training curse. The mean BLL for the instructors' group was 5.5 μg/dL ± 0.6. The mean BLL for the cadets' group before the training was 3.3 μg/dL ± 0.15 and after the training the main BLL was 18.2 μg/d L± 1.5. Samples were analyzed by Inductively Coupled Plasma Mass Spectrometer (ICP-MS). All the participants in the training curse had significantly increased BLL (mean increment about 15 μg/dL) after the three days indoor shooting season. In conclusion, occupational lead exposure in indoor firing ranges is a source of lead exposure in Brazilian police officers, and appears to be a health risk, especially when heavy weapons with lead-containing ammunition are used in indoor environments during the firing training seasons.

A probable role of blood lead levels on some haematological parameters in traffic police, Lahore, Pakistan

The impact of elevated blood lead level on some haematological parameters was studied in the field force of Lahore traffic police, in Pakistan. The blood samples were tested for total leucocytes count (TLC) and differential leucocytes count in the persons with high and low blood lead levels. The TLC and percentage of neutrophils and eosinophils were observed as being significantly elevated in the policemen. No significant change was observed in the percentage of lymphocytes, while the percentage of monocytes was observed as being significantly less in the field force of traffic police.

Very high blood lead levels among adults - United States, 2002-2011

Over the past several decades there has been a remarkable reduction in environmental sources of lead, improved protection from occupational lead exposure, and an overall decreasing trend in the prevalence of elevated blood lead levels (BLLs) in U.S. adults. As a result, the U.S. national BLL geometric mean among adults was 1.2 µg/dL during 2009-2010. Nonetheless, lead exposures continue to occur at unacceptable levels. Current research continues to find that BLLs previously considered harmless can have harmful effects in adults, such as decreased renal function and increased risk for hypertension and essential tremor at BLLs <10 µg/dL. CDC has designated 10 µg/dL as the reference BLL for adults; levels ≥10 µg/dL are considered elevated. CDC's Adult Blood Lead Epidemiology and Surveillance (ABLES) program tracks elevated BLLs among adults in the United States. In contrast to the CDC reference level, prevailing Occupational Safety and Health Administration (OSHA) lead standards allow workers removed from lead exposure to return to lead work when their BLL falls below 40 µg/dL. During 2002-2011, ABLES identified 11,536 adults with very high BLLs (≥40 µg/dL). Persistent very high BLLs (≥40 µg/dL in ≥2 years) were found among 2,210 (19%) of these adults. Occupational exposures accounted for 7,076 adults with very high BLLs (91% of adults with known exposure source) and 1,496 adults with persistent very high BLLs. Adverse health effects associated with very high BLLs underscore the need for increased efforts to prevent lead exposure at workplaces and in communities.

Lead and cadmium levels in cattle muscle and edible tissues collected from a slaughter slab in Nigeria

Contamination levels of lead (Pb) and cadmium (Cd) in muscles, liver and kidney of 50 randomly selected, freshly slaughtered cattle in Ogun State, Nigeria were assessed using an official procedure and atomic absorption spectrophotometry. Results showed that Pb and Cd were present in all of the tested samples. Mean Pb concentrations were 0.721 ± 0.180 mg kg(-1), 0.809 ± 0.220 mg kg(-1) and 0.908 ± 0.422 mg kg(-1) in muscle, liver and kidney tissues, respectively. Mean Cd concentrations were 0.157 ± 0.049 mg kg(-1), 0.172 ± 0.071 mg kg(-1) and 0.197 ± 0.070 mg kg(-1) in muscle, liver and kidney tissues, respectively. Pb and Cd levels in muscle versus kidney tissues and also in liver versus kidney samples were significantly different (p < 0.05). Mean Pb concentrations in all tested tissues were significantly higher than the International Standards while the mean Cd concentrations in liver and kidney samples were within the limits of these standards.

Safety and toxicity issues associated with lead-based traditional herbo-metallic preparations

ETHNOPHARMACOLOGICAL RELEVANCE

Herbal and herbo-mineral preparations are being traditionally used in Indian medicines. The herbo-mineral preparations have several benefits that have been instrumental in their widespread use in treatment of different disorders by traditional medicinal practitioners. These include better stability, lower dosage, ease of storability and sustained availability. Naga bhasma (lead sulphide ash), a traditional Indian herbo-mineral medication prepared using lead and several herbal ingredients, has been used as an oral medicine in India for many years for the treatment of diabetes, spleen enlargement, diarrhoea and various skin diseases. The elaborate preparation protocol involved in the traditional medicines is believed to modify the toxic nature of the precursor (metal) and adds therapeutic value. But modern scientists claim that these preparations are toxic to health as they contain large amount of metal. Many factors such as preparation based factors, chemical nature based factors, vehicle used, therapy associated factors, pharmacological factors, etc, determine whether the traditional medicines are toxic or not. This review focuses on the safety and critical issues associated with Naga bhasma-a lead based ayurvedic medicine.

MATERIALS AND METHODS

The detailed review of literature about Naga bhasma apart from other lead based formulations are carried out by utilizing the resources including, classical Indian text books, databases such as Pub med, Scopus, Science direct and few other web sources.

RESULTS

Though metallic lead is known to be toxic to the biological system, no compelling evidence has been put forth to suggest any toxic manifestations of Naga bhasma. The elemental characterization of preparations containing Naga bhasma has shown extremely high levels of lead content and various parameters must be taken into consideration in deciding the safety and critical issues present in traditional medicines. As there are no molecular targets available for most of the traditional medicine, it is difficult to assure the safety in using this traditional preparation. Highly intensive research encompassing physico-chemical, engineering as well as biological aspects need to be carried out to understand the applicability of such preparations in a modern context.

CONCLUSION

As there are no molecular targets available for most of the traditional medicine, it is difficult to assure the safety in using this traditional preparation. Highly intensive research encompassing physico-chemical, engineering as well as biological aspects need to be carried out to understand the applicability of such preparations in a modern context.

A case report of adult lead toxicity following use of Ayurvedic herbal medication

Introduction

Ayurvedic medications consist of herbs that may be intentionally combined with metals, such as lead, mercury, iron, and zinc. Ayurvedic practitioners and their patients believe that the toxic properties of the metals are reduced or eliminated during preparation and processing.

Case report

A 69 year old Caucasian male retired professional with a prior history of stroke presented for evaluation of new onset depression, fatigue, generalized weakness, constipation, anorexia, and weight loss. History revealed that his symptoms were temporally related to initiation of an Ayurvedic herbal medication. The patient had been previously admitted to another hospital for these symptoms and was found to have a severe anemia for which no etiology was found. Laboratory tests revealed an elevated blood lead level and a diagnosis of symptomatic lead toxicity was made. The patient was treated with intramuscular, intravenous, and oral chelation therapy to promote lead excretion. Because of complaints of continued poor mental function, neuropsychological tests were administered before and after one of the chelation treatments and showed improvement in measures of attention and other cognitive domains. In addition, the patient was able to discontinue use of antidepressant medication after chelation.

Discussion

A high index of suspicion of metal toxicity is necessary among persons with characteristic symptoms and signs in the absence of occupational exposure. Despite limited evidence for chelation in adults and in those with modest blood lead levels, this patient appeared to benefit from repeated chelation therapy. Both allopathic and alternative medicine practitioners and public health specialists need to be aware of the potential for contamination of and side effects from alternative pharmacologic and herbal therapies.

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

OBJECTIVES

This study evaluated multiple blood lead measures collected over time and assessed differences arising from exposure and testing variability.

METHODS

Blood lead data was used to compare individuals from manufacturing and construction occupational cohorts. Trends of blood lead levels (BLLs) over time were analysed using mixed model analysis. Random selection of BLL values was used to determine the improvement in the precision of mean BLL estimates as the number of tests increased.

RESULTS

From 2003-2007, there were 619 manufacturing and 657 construction workers with more than one blood lead test reported. Construction workers had much more variability in their blood lead trends. They also tended to have less frequent follow-up blood tests compared with manufacturing workers. Both occupational cohorts had persistent BLLs that resulted in many workers with chronically high blood lead values (>25 µg/dL). Approximately 11.2% of construction workers and 34.8% of manufacturing workers with an initial blood lead test above 25 µg/dL remained above this blood level through the study period. The precision in the mean BLL estimates increased more substantially for construction workers when compared with manufacturing workers as the number of blood lead tests per worker increased.

CONCLUSIONS

This study confirmed differences in the pattern of blood lead tests and the resulting trends for manufacturing compared with construction workers. It also suggested that the number of blood lead tests performed on a worker is an important consideration in the assessment of a worker's mean blood lead estimate, and this is particularly true for workers with highly variable exposures.

Lead toxicity and management of gunshot wounds in the lumbar spine

INTRODUCTION

Gunshot wounds are one of the commonest causes of spinal injury. Management of these patients differs from other blunt trauma injuries to the spine. We present a case of a gunshot wound to the lumbar spine that occurred in 1985 which was treated non-operatively.

METHODS

In the last 10 years, the patient was admitted multiple times for confusion and lead toxicity with blood levels over 100 μg/dl. Inpatient chelation therapy was implemented. After multiple recommendations for surgery, the patient agreed to have as much of the bullet removed as possible. The patient successfully underwent decompression and fusion from both anterior and posterior approaches. Lead levels subsequently declined.

CONCLUSION

The purpose of this paper is to show a case of a gunshot wound to the spine that ultimately caused plumbism and required surgery. Technical aspects of the surgery are described as well as pre- and post-procedural imaging. Recommendations for the general management of spine gunshot wounds are also described.

Clinical, toxicological, biochemical, and hematologic parameters in lead exposed workers of a car battery industry

BACKGROUND

Lead is a toxic element which causes acute, subacute or chronic poisoning through environmental and occupational exposure. The aim of this study was to investigate clinical and laboratory abnormalities of chronic lead poisoning among workers of a car battery industry.

METHODS

Questionnaires and forms were designed and used to record demographic data, past medical histories and clinical manifestations of lead poisoning. Blood samples were taken to determine biochemical (using Auto Analyzer; Model BT3000) and hematologic (using Cell Counter Sysmex; Model KX21N) parameters. An atomic absorption spectrometer (Perkin-Elmer, Model 3030, USA) was used to determine lead concentration in blood and urine by heated graphite atomization technique.

RESULTS

A total of 112 men mean age 28.78±5.17 years, who worked in a car battery industry were recruited in the present study. The most common signs/symptoms of lead poisoning included increased excitability 41.9%, arthralgia 41.0%, fatigue 40.1%, dental grey discoloration 44.6%, lead line 24.1%, increased deep tendon reflexes (DTR) 22.3%, and decreased DTR (18.7%). Blood lead concentration (BLC) was 398.95 µg/L±177.40, which was significantly correlated with duration of work (P=0.044) but not with the clinical manifestations of lead poisoning. However, BLC was significantly correlated with urine lead concentration (83.67 µg/L±49.78; r(2)=0.711; P<0.001), mean corpuscular hemoglobin (r=-0.280; P=0.011), mean corpuscular hemoglobin concentration (r=-0.304; P=0.006) and fasting blood sugar or FBS (r=-0.258; P=0.010).

CONCLUSION

Neuropsychiatric and skeletal findings were common manifestations of chronic occupational lead poisoning. BLC was significantly correlated with duration of work, urine lead concentration, two hemoglobin indices and FBS.

Tracking blood lead and zinc protoporphyrin levels in Andean adults working in a lead contaminated environment

The purpose of this study was to investigate current blood lead (PbB) and zinc protoporphyrin (ZPP) levels in adults presently living in environmentally Pb-contaminated Andean communities, and to compare the findings with the PbB and ZPP levels of Pb-exposed adult cohorts from the same study area tested between 1996 and 2007. Blood samples from 39 adults were measured for PbB and ZPP concentrations. The current mean PbB level (22.7 μg/dl) was significantly lower than the mean (37.9 μg/dl) of the initial 1996 cohort. PbB levels for the 1997, 1998, 2003, and 2006 cohorts were also significantly lower than the levels for the 1996 group. Elevated ZPP/heme ratios of 103.3, 128.4, and 134.2 μmol/mol were not significantly different for the 2006, 2007, and 2012 groups, indicating chronic Pb exposure. While ZPP levels of Andean Ecuadorian Pb-glazing workers have remained elevated, PbB levels declined. Lead exposure of the workers needs to be continually monitored.

Perspective on lead toxicity, a comparison between the United States and Iran

Lead is a pervasive toxin that has been implicated in human poisonings throughout history. Exposure mitigation strategies in the United States and worldwide have led to a decline in symptomatic poisonings and population blood lead levels; however, lead remains a major health hazard. In this article, we review the history of lead toxicity, clinical manifestations ranging from subclinical and subtle features to life-threatening complications, and the subsequent public health interventions in the US. In addition, we explore common routes of lead exposure and the unique differences between the US and Iran. Although the US has made significant strides with regard to this public health issue, lead poisoning in both countries continues to be a health hazard in the adult and pediatric populations. It is also critical to consider natural disasters and reconstruction efforts as potential sources of lead contamination. In conclusion, we make recommendations that both the US and Iranian authorities can implement to eradicate lead as a public health hazard.

Buyers beware: lead poisoning due to Ayurvedic medicine

A 29-year-old man, who recently emigrated from India, presented with a 2-week history of abdominal pain, as well as nausea, constipation, and fatigue. He underwent removal of a parathyroid adenoma 6 weeks prior to admission and received a locally made Indian traditional medicine (Ayurveda) for pain control; however, this information was not initially available. He was instructed to take approximately 15 g/day. Initial evaluation revealed a normocytic anemia, but other workup including imaging and endoscopy was unrevealing. Given his recent use of Ayurvedic medicines, we tested for lead poisoning and found a blood lead level of 72 mcg/dl. We sent his medicine for analysis and found it had a high lead concentration of 36,000 mcg/g, which is over 25,000 times the maximum daily dose. He improved with cessation of the medicine and treatment with succimer. Lead poisoning can present with a variety of nonspecific signs and symptoms, including abdominal pain and anemia. Ayurvedic medicines, as well as traditional medicines from other cultures, may be a source of lead or other heavy metals. It is essential for physicians to be aware of adverse effects of Ayurvedic medicines as they are easily available and increasing in popularity.

The role of α-synuclein and tau hyperphosphorylation-mediated autophagy and apoptosis in lead-induced learning and memory injury

Lead (Pb) is a well-known heavy metal in nature. Pb can cause pathophysiological changes in several organ systems including central nervous system. Especially, Pb can affect intelligence development and the ability of learning and memory of children. However, the toxic effects and mechanisms of Pb on learning and memory are still unclear. To clarify the mechanisms of Pb-induced neurotoxicity in hippocampus, and its effect on learning and memory, we chose Sprague-Dawley rats (SD-rats) as experimental subjects. We used Morris water maze to verify the ability of learning and memory after Pb treatment. We used immunohistofluorescence and Western blotting to detect the level of tau phosphorylation, accumulation of α-synuclein, autophagy and related signaling molecules in hippocampus. We demonstrated that Pb can cause abnormally hyperphosphorylation of tau and accumulation of α-synuclein, and these can induce hippocampal injury and the ability of learning and memory damage. To provide the new insight into the underlying mechanisms, we showed that Grp78, ATF4, caspase-3, autophagy-related proteins were induced and highly expressed following Pb-exposure. But mTOR signaling pathway was suppressed in Pb-exposed groups. Our results showed that Pb could cause hyperphosphorylation of tau and accumulation of α-synuclein, which could induce ER stress and suppress mTOR signal pathway. These can enhance type II program death (autophgy) and type I program death (apoptosis) in hippocampus, and impair the ability of learning and memory of rats. This is the first evidence showing the novel role of autophagy in the neurotoxicity of Pb.

Blood lead levels of residents living around 350 abandoned metal mines in Korea

In 2007, as part of the control and prevention of environmental contamination threatening public health, the Korean Ministry of Environment planned to implement a national biomonitoring survey of three metals: lead, cadmium, and mercury in the blood of residents living near 350 abandoned metal mines known to be contaminated and as possible threats to the health of inhabitants. Thus, we investigated demographic and lifestyle variables and blood lead levels in residents living around the mines and compared them against those of control subjects. We measured the blood lead concentrations in 14,849 subjects (14,132 from nearby the 350 abandoned metal mines and 717 subjects from eight control areas). A questionnaire was provided to all subjects to determine gender, age, mining experience, period of time living in the vicinity of mines, smoking status, and personal perception of abandoned mines as a health risk. The geometric means (95% confidence intervals) of the blood lead levels of residents living around the abandoned metal mines and control areas were 3.017 (2.996-3.037 μg/dL) [female, 2.797 μg/dL (2.771-2.822 μg/dL); male, 3.330 μg/dL (3.298-3.363 μg/dL)] and 2.757 (2.677-2.837 μg/dL) [female, 2.604 μg/dL (2.506-2.700 μg/dL); male, 2.993 μg/dL (2.859-3.126 μg/dL)], respectively. Among residents of the mining areas, nonsmokers and residents who had no mining experience showed significantly lower mean blood lead levels than did smokers, past smokers, and those with mining experience. The mean blood lead concentrations of residents who expressed some concern about the abandoned mines were significantly higher than those of residents without concerns. The mean blood lead concentration of residents living around the abandoned mines was significantly higher than that of residents living in control areas as well as that of the general adult Korean population. We also confirmed that smoking is an important variable to consider, as it increases blood lead concentration.

Gender-dependent behavioural impairment and brain metabolites in young adult rats after short term exposure to lead acetate

We investigated the behavioural effects of short-term lead (Pb) exposure in adult rats producing blood Pb concentration (<10 μg/dL) below those associated with neurological impairment in occupationally exposed individuals. In order to assess gender differences, we performed parallel behavioural experiments in male and female rats. Exposure to Pb acetate (50 mg/L in drinking water) for 30-45 days induced behavioural alterations consisting in hyperactivity in a novel environment and impairment of spatial memory. These effects were observed only in male rats. Object recognition, motor coordination were unaffected by Pb exposure. Magnetic resonance spectroscopy allows in vivo assessment of main brain metabolites (glutamate/glutamine, creatine, myoinositol, N-acetylaspartate and choline) whose changes have been demonstrated in several central nervous system pathologies. Exposure to Pb did not affect metabolite profile in the striatum and increase myoinositol signal in the hippocampus of male rats. The increase in myoinositol in hippocampus suggests early Pb-induced alteration in glial metabolism in this brain region and may represent a potential marker of early brain dysfunction during Pb exposure.

Air and blood lead levels in lead acid battery recycling and manufacturing plants in Kenya

The concentration of airborne and blood lead (Pb) was assessed in a Pb acid battery recycling plant and in a Pb acid battery manufacturing plant in Kenya. In the recycling plant, full-shift area samples taken across 5 days in several production sections showed a mean value ± standard deviation (SD) of 427 ± 124 μg/m(3), while area samples in the office area had a mean ± SD of 59.2 ± 22.7 μg/m(3). In the battery manufacturing plant, full-shift area samples taken across 5 days in several production areas showed a mean value ± SD of 349 ± 107 μg/m(3), while area samples in the office area had a mean ± SD of 55.2 ± 33.2 μg/m(3). All these mean values exceed the U.S. Occupational Safety and Health Administration's permissible exposure limit of 50 μg/m(3) as an 8-hr time-weighted average. In the battery recycling plant, production workers had a mean blood Pb level ± SD of 62.2 ± 12.7 μg/dL, and office workers had a mean blood Pb level ± SD of 43.4 ± 6.6 μg/dL. In the battery manufacturing plant, production workers had a mean blood Pb level ± SD of 59.5 ± 10.1 μg/dL, and office workers had a mean blood Pb level ± SD of 41.6 ± 7.4 μg/dL. All the measured blood Pb levels exceeded 30 μg/dL, which is the maximum blood Pb level recommended by the ACGIH(®). Observations made in these facilities revealed numerous sources of Pb exposure due to inadequacies in engineering controls, work practices, respirator use, and personal hygiene.

Comparison of therapeutic effects of garlic and d-Penicillamine in patients with chronic occupational lead poisoning

Previous studies on animals have revealed that garlic (Allium sativum) is effective in reducing blood and tissue lead concentrations. The aim of this study was to investigate therapeutic effects of garlic and compare it with d-penicillamine in patients with chronic lead poisoning. After coordination and obtaining informed consent, clinical examinations and blood lead concentration (BLC) of 117 workers at a car battery industry were investigated. BLC was determined by heated graphite atomization technique of an atomic absorption spectrometer. The workers were randomly assigned into two groups of garlic (1200 μg allicin, three times daily) and d-penicillamine (250 mg, three times daily) and treated for 4 weeks. BLC was determined again 10days post-treatment. Clinical signs and symptoms of lead poisoning were also investigated and compared with the initial findings. Clinical improvement was significant in a number of clinical manifestations including irritability (p = 0.031), headache (p = 0.028), decreased deep tendon reflex (p=0.019) and mean systolic blood pressure (0.021) after treatment with garlic, but not d-penicillamine. BLCs were reduced significantly (p=0.002 and p=0.025) from 426.32±185.128 to 347.34±121.056 μg/L and from 417.47±192.54 to 315.76±140.00μg/L in the garlic and d-penicillamine groups, respectively, with no significant difference (p=0.892) between the two groups. The frequency of side effects was significantly (p=0.023) higher in d-penicillamine than in the garlic group. Thus, garlic seems safer clinically and as effective as d-penicillamine. Therefore, garlic can be recommended for the treatment of mild-to-moderate lead poisoning.

Association of low-level blood lead and blood pressure in NHANES 1999-2006

This study investigated whether low blood-lead levels (≤10 μg/dL) were associated with blood pressure (BP) outcomes. The authors analyzed data from National Health and Nutrition Examination Survey 1999-2006 and participants aged 20 years or older. Outcome variables were systolic and diastolic BP measurements, pulse pressure, and hypertension status. Multivariable linear and logistic regressions stratified by race/ethnicity and gender were performed. Blood lead levels (BLL) were significantly correlated with higher systolic BP among black men and women, but not white or Mexican-American participants. BLLs were significantly associated with higher diastolic BPs among white men and women and black men, whereas, a negative association was observed in Mexican-American men that had, also, a wider pulse pressure. Black men in the 90th percentile of blood lead distribution (BLL≥3.50 μg/dL) compared to black men in the 10th percentile of blood lead distribution (BLL≤0.7 μg/dL) had a significant increase of risk of having hypertension (adjusted POR=2.69; 95% CI: 1.08-6.72). In addition, blood cadmium was significantly associated with hypertension and systolic and diastolic blood. This study found that, despite the continuous decline in blood lead in the U.S. population, lead exposure disparities among race and gender still exist.

How cumulative risks warrant a shift in our approach to racial health disparities: the case of lead, stress, and hypertension

Blacks have persistently higher rates of high blood pressure, or hypertension, compared to whites, resulting in higher health costs and mortality rates. Recent research has shown that social and environmental factors-such as high levels of stress and exposure to lead-may explain racial disparities in hypertension. Based on these findings, we recommend a fundamental shift in approaches to health disparities to focus on these sorts of cumulative risks and health effects. Federal and state agencies and research institutions should develop strategic plans to learn more about these connections and apply the broader findings to policies to reduce health disparities.

Lead: ongoing public and occupational health issues in vulnerable populations: a case study

BACKGROUND

Lead has been recognized increasingly as a public health risk, although with the introduction of wide-ranging occupational and public health measures, levels of blood lead in the general population of the UK and other developed nations have been in decline in recent years. Nonetheless, cases of lead poisoning still occur.

METHODS

We report on a large cluster of exposed lead workers and their families, including several children. The focus of the occupational and public health investigations was to identify the different groups at risk and the pathways by which potential exposures were taking place.

RESULTS

Lead in the workplace was found to account for the raised blood lead levels amongst the workers with exposure occurring as a result of insufficient demarcation between 'clean' and 'dirty' areas, and from contamination of personal belongings with lead. Furthermore, there was evidence of para-occupational exposure of family members.

CONCLUSIONS

The successful control of lead in this case required multidisciplinary working. Efforts included extensive workplace controls, along with the education and care of workers and their families, though complicated by lack of familiarity with the UK health service amongst the affected groups, language barriers, underlying low levels of literacy and high mobility.

Review: Lead exposure in battery manufacturing and recycling in developing countries and among children in nearby communities

The battery industry is the largest consumer of lead, using an estimated 80% of the global lead production. The industry is also rapidly expanding in emerging market countries. A review of published literature on exposures from lead-acid battery manufacturing and recycling plants in developing countries was conducted. The review included studies from 37 countries published from 1993 to 2010 and excluded facilities in developed countries, such as the United States and those in Western Europe, except for providing comparisons to reported findings. The average worker blood lead level (BLL) in developing countries was 47 μg/dL in battery manufacturing plants and 64 μg/dL in recycling facilities. Airborne lead concentrations reported in battery plants in developing countries averaged 367 μg/m3, which is 7-fold greater than the U.S. Occupational Safety and Health Administration's 50 μg/m3 permissible exposure limit. The geometric mean BLL of children residing near battery plants in developing countries was 19 μg/dL, which is about 13-fold greater than the levels observed among children in the United States. The blood lead and airborne lead exposure concentrations for battery workers were substantially higher in developing countries than in the United States. This disparity may worsen due to rapid growth in lead-acid battery manufacturing and recycling operations worldwide. Given the lack of regulatory and enforcement capacity in most developing countries, third-party certification programs may be the only viable option to improve conditions.

Characterization of lead in US workplaces using data from OSHA's integrated management information system

BACKGROUND

Lead hazards continue to be encountered in the workplace. OSHA's Integrated Management Information System (IMIS) is the largest available database containing sampling results in US workplaces.

METHODS

Personal airborne lead sampling results in IMIS were extracted for years 1979-2008. Descriptive analyses, geographical mapping, and regression modeling of results were performed.

RESULTS

Seventy-nine percent of lead samples were in the manufacturing sector. Lead sample results were highest in the construction sector (median = 0.03 mg/m(3) ). NORA sector, year, OSHA region, number of employees at the worksite, federal/state OSHA plan, unionization, advance notification, and presence of an employee representative were statistically associated with having a lead sample result exceed the PEL.

CONCLUSIONS

Lead concentrations within construction have been higher than any other industry. Lead hazards have been most prevalent in the north and northeastern US. IMIS data can be useful as a surveillance tool and for targeting prevention efforts toward hazardous industries.

Treatment of chronic lead toxicity with succimer: a case series of 2 adults with retained lead shotgun fragments

Few recommendations exist for management of chronic lead toxicity in instances when the source of lead exposure cannot be removed.

CASES

We describe 2 patients who had shotgun wounds resulting in multiple retained lead pellets. They developed elevated blood lead levels and were treated with 2 weeks of high-dose oral succimer before being placed on maintenance oral succimer therapy with the goal of sustaining suppressed lead levels.

DISCUSSION

Retained lead pellets have been associated with increasing blood lead levels over time. Chronic lead toxicity can cause significant morbidity. Few treatments for lead toxicity are available, and there is scarce data on maintenance therapy for patients who have large numbers of retained shotgun pellets.

CONCLUSIONS

This case series documents 2 patients who continue on maintenance oral chelation therapy with succimer in an effort to prevent the sequelae of chronic lead toxicity by maintaining blood lead levels less than 20 μg/dL.

Acute lead exposure increases arterial pressure: role of the renin-angiotensin system

Background

Chronic lead exposure causes hypertension and cardiovascular disease. Our purpose was to evaluate the effects of acute exposure to lead on arterial pressure and elucidate the early mechanisms involved in the development of lead-induced hypertension.

Methodology/Principal Findings

Wistar rats were treated with lead acetate (i.v. bolus dose of 320 µg/Kg), and systolic arterial pressure, diastolic arterial pressure and heart rate were measured during 120 min. An increase in arterial pressure was found, and potential roles of the renin-angiotensin system, Na⁺,K⁺-ATPase and the autonomic reflexes in this change in the increase of arterial pressure found were evaluated. In anesthetized rats, lead exposure: 1) produced blood lead levels of 37±1.7 µg/dL, which is below the reference blood concentration (60 µg/dL); 2) increased systolic arterial pressure (Ct: 109±3 mmHg vs Pb: 120±4 mmHg); 3) increased ACE activity (27% compared to Ct) and Na⁺,K⁺-ATPase activity (125% compared to Ct); and 4) did not change the protein expression of the α1-subunit of Na⁺,K⁺-ATPase, AT₁ and AT₂. Pre-treatment with an AT₁ receptor blocker (losartan, 10 mg/Kg) or an ACE inhibitor (enalapril, 5 mg/Kg) blocked the lead-induced increase of arterial pressure. However, a ganglionic blockade (hexamethonium, 20 mg/Kg) did not prevent lead's hypertensive effect.

Conclusion

Acute exposure to lead below the reference blood concentration increases systolic arterial pressure by increasing angiotensin II levels due to ACE activation. These findings offer further evidence that acute exposure to lead can trigger early mechanisms of hypertension development and might be an environmental risk factor for cardiovascular disease.

Whole blood lead levels are associated with radiographic and symptomatic knee osteoarthritis: a cross-sectional analysis in the Johnston County Osteoarthritis Project

INTRODUCTION

Lead (Pb) is known to affect bone, and recent evidence suggests that it has effects on cartilage as well. As osteoarthritis (OA) is a highly prevalent disease affecting bone and cartilage, we undertook the present analysis to determine whether whole blood Pb levels are associated with radiographic and symptomatic OA (rOA and sxOA, respectively) of the knee.

METHODS

The analysis was conducted using cross-sectional data from the Johnston County Osteoarthritis Project, a rural, population-based study, including whole blood Pb levels, bilateral posteroanterior weight-bearing knee radiography and knee symptom data. rOA assessment included joint-based presence (Kellgren-Lawrence (K-L) grade 2 or higher) and severity (none, K-L grade 0 or 1; mild, K-L grade 2; moderate or severe, K-L grade 3 or 4), as well as person-based laterality (unilateral or bilateral). SxOA was deemed present (joint-based) in a knee on the basis of K-L grade 2 or higher with symptoms, with symptoms rated based on severity (0, rOA without symptoms; 1, rOA with mild symptoms; 2, rOA with moderate or severe symptoms) and in person-based analyses was either unilateral or bilateral. Generalized logit or proportional odds regression models were used to examine associations between the knee OA status variables and natural log-transformed blood Pb (ln Pb), continuously and in quartiles, controlling for age, race, sex, body mass index (BMI), smoking and alcohol drinking.

RESULTS

Those individuals with whole blood Pb data (N = 1,669) had a mean (±SD) age of 65.4 (±11.0) years and a mean BMI of 31.2 (±7.1) kg/m2, including 66.6% women and 35.4% African-Americans, with a median blood Pb level of 1.8 μg/dl (range, 0.3 to 42.0 μg/dl). In joint-based analyses, for every 1-U increase in ln Pb, the odds of prevalent knee rOA were 20% higher (aOR, 1.20; 95% CI, 1.01 to 1.44), while the odds of more severe rOA were 26% higher (aOR, 1.26; 95% CI, 1.05 to 1.50, under proportional odds). In person-based analyses, the odds of bilateral rOA were 32% higher for each 1-U increase in ln Pb (aOR, 1.32; 95% CI, 1.03 to 1.70). Similarly for knee sxOA, for each 1-U increase in ln Pb, the odds of having sxOA were 16% higher, the odds of having more severe symptoms were 17% higher and the odds of having bilateral knee symptoms were 25% higher. Similar findings were obtained with regard to ln Pb in quartiles.

CONCLUSIONS

Increases in the prevalence and severity measures for both radiographically and symptomatically confirmed knee OA (although statistically significant only for rOA) were observed with increasing levels of blood Pb, suggesting that Pb may be a potentially modifiable environmental risk factor for OA.

Low-level lead exposure increases systolic arterial pressure and endothelium-derived vasodilator factors in rat aortas

Chronic lead exposure induces hypertension and alters endothelial function. However, treatment with low lead concentrations was not yet explored. We analyzed the effects of 7 day exposure to low lead concentrations on endothelium-dependent responses. Wistar rats were treated with lead (1st dose 4 µg/100 g, subsequent dose 0.05 µg/100 g, i.m. to cover daily loss) or vehicle; blood levels attained at the end of treatment were 9.98 µg/dL. Lead treatment had the following effects: increase in systolic blood pressure (SBP); reduction of contractile response to phenylephrine (1 nM–100 µM) of aortic rings; unaffected relaxation induced by acetylcholine (0.1 nM–300 µM) or sodium nitroprusside (0.01 nM–0.3 µM). Endothelium removal, N^G-nitro-L-arginine methyl ester (100 µM) and tetraethylammonium (2 mM) increased the response to phenylephrine in treated rats more than in untreated rats. Aminoguanidine (50 µM) increased but losartan (10 µM) and enalapril (10 µM) reduced the response to phenylephrine in treated rats. Lead treatment also increased aortic Na⁺/K⁺-ATPase functional activity, plasma angiotensin-converting enzyme (ACE) activity, protein expression of the Na⁺/K⁺-ATPase alpha-1 subunit, phosphorylated endothelial nitric oxide synthase (p-eNOS), and inducible nitric oxide synthase (iNOS). Our results suggest that on initial stages of lead exposure, increased SBP is caused by the increase in plasma ACE activity. This effect is accompanied by increased p-eNOS, iNOS protein expression and Na⁺/K⁺-ATPase functional activity. These factors might be a compensatory mechanism to the increase in SBP.

Blood lead levels and risk factors in pregnant women from Durango, Mexico

In this cross-sectional study the authors determined blood lead levels (BLLs) and some risk factors for lead exposure in pregnant women. Two hundred ninety-nine pregnant women receiving medical attention by the Secretary of Health, State of Durango, Mexico, participated in this study between 2007 and 2008. BLLs were evaluated with graphite furnace atomic absorption spectrometry. The authors used Student t test, 1-way analysis of variance (ANOVA), and linear regression as statistical treatments. BLLs ranged from 0.36 to 23.6 μg/dL (mean = 2.79 μg/dL, standard deviation = 2.14). Multivariate analysis showed that the main predictors of BLLs were working in a place where lead is used, using lead glazed pottery, and eating soil.

Increased levels of lead in the blood and frequencies of lymphocytic micronucleated binucleated cells among workers from an electronic-waste recycling site

In recent years, adverse health effects of chemicals from electronic waste (e-waste) have been reported. However, little is known about the genotoxic effects of chemicals in e-waste. In the present study, air concentrations of the toxic metals at e-waste and control sites were analyzed using inductively-coupled plasma mass spectrometry. Levels of toxic metals (lead, copper and cadmium) in blood and urine were detected using atomic absorption spectrophotometry in 48 exposed individuals and 56 age- and sex-matched controls. The frequencies of lymphocytic micronucleated binucleated cells (MNBNCs) were determined using a cytokinesis-block micronucleus assay. Results indicated that blood lead levels were significantly higher in the exposed group (median: 11.449 μg/dL, 1st/3rd quartiles: 9.351-14.410 μg/dL) than in the control group (median: 9.104 μg/dL, 1st/3rd quartiles: 7.275-11.389 μg/dL). The exposed group had higher MNBNCs frequencies (median: 4.0 per thousand, 1st/3rd quartiles: 2.0-7.0 per thousand) compared with the controls (median: 1.0 per thousand, 1st/3rd quartiles: 0.0-2.0 per thousand). Additionally, MNBNCs frequencies and blood lead levels were positively correlated (r = 0.254, p<0.01). Further analysis suggested that a history of working with e-waste was a predictor for increased blood lead levels and MNBNCs frequencies in the subjects. The results suggest that both the living and occupational environments at the e-waste site may be risk factors for increased MNBNCs frequencies among those who are exposed.

Lead exposure in female workers who are pregnant or of childbearing age

In adults, high-level lead exposure often occurs in the lead-related industries. Acute lead poisoning has become rare, but chronic exposure to low-level lead remains a public health issue. With recent advances in our understanding of lead toxicity at low-levels, researchers have shifted their focus to studying lead at concentrations below those currently recommended as 'acceptable' in worker protection. As gender plays an important role in the storage, biokinetics, and toxicity of lead, it seems inappropriate to extrapolate findings of lead exposure in men to women. Women's bones release lead more slowly to the bloodstream, so blood levels remain increased for a long time after cessation of high exposure, reflecting the endogenous source of the lead. Particularly in pregnant women, bone lead release could influence health in pregnancy and be extremely harmful to the rapidly growing and developing fetus. Accordingly, female workers of childbearing age should avoid excessive lead exposure. However, because studies of pregnant workers encounter many difficulties and inconveniences, sufficient research has not been conducted in this area. As an alternative, a group of non-occupationally exposed women, matched as well as possible for anthropometric and reproductive variables and with almost the same levels of blood lead, could be recruited for survey.

The evaluation of a health education campaign on the use of leave from work during pregnancy

Background

The Italian Protective Maternity Legislation allows a woman to apply for early maternity leave from work during pregnancy if she is affected by health problems (option A) or if her working conditions are incompatible with pregnancy (option B). A community based health education program, implemented between 1995 to 1998 in North Eastern Italy, provided counseling (by a team of gynecologists, pediatricians, geneticists, psychologists and occupational physicians), and an information leaflet detailing the risks during pregnancy and the governmental benefits available to expectant mothers. This leaflet was distributed to women who were under occupational medical surveillance and to women attending any healthcare office and outpatient department and was also mailed to women working at home as shoemakers.

The effectiveness of this intervention has been evaluated in this investigation using an evidence based approach.

Methods

A quasi-experimental design was adopted, applying several outcome measurements before (1989 to 1994) and after (1999 to 2005) the intervention. The outcome (ratio B/A) is the number of women receiving approval for B (circumstance where the pregnant woman is employed to undertake activities forbidden under the Article 7 of Law 151/2001, and it is impossible to change her duties) to those receiving approval for A (risky pregnancy due to personal medical conditions, Article 17 of the same Law). A linear regression coefficient (for B/A against years) was obtained separately for time periods "before" (1989-94) and "after" (1999-2005) the intervention program. The two regression coefficients were compared using a t-test.

Results

The trend over-time for the ratio B/A was steady before the initial intervention (y = 0.008x - 16.087; t = 2.09; p > 0.05) then increased considerably (y = 0.0426x - 84.89; t = 19.55; p < 0.001) in coincidence with the start of the education campaign. There was a significant difference between the two regression coefficients (t = 7.58; p < 0.001).

Conclusion

From a bureaucratic perspective Option B is far more complicated than A. In fact it implies an active approach involving an arrangement between the claimant and the employer, who has to certify to the relevant Authority that the woman's working conditions are incompatible with pregnancy. The increasing number of women availing of option B, as recommended, therefore suggests the suitability of such educational campaign(s).

A safe strategy to decrease fetal lead exposure in a woman with chronic intoxication

During pregnancy skeletal lead is mobilized by maternal bone turnover and can threaten fetal development. The exact strategy suggested to women of childbearing age, who were chronically exposed to lead, and, thus, have high bone lead burden, is not well established. We describe 4 years of follow-up of a 29-year-old woman with chronic lead intoxication. We (a) advised her to delay conception until 'toxicological clearance', (b) treated her with multiple courses of lead chelator, DMSA, and (c) prescribed oral calcium. Patient had low blood lead and protoporphyrin level during pregnancy until delivery. Delaying conception, lead chelation, and calcium supplementation can decrease fetal exposure.

Association of occupation with prevalent hypertension in an elderly East German population: an exploratory cross-sectional analysis

PURPOSE

Hypertension is one of the most relevant risk factors for cardiovascular disease; however, little is known about differences in hypertension by occupation. The aim of this study was to explore the association between occupational group and prevalent hypertension.

METHODS

Cross-sectional data of the CARLA study were used, a representative sample of an East German population aged 45-83. Job titles of the current or last held occupation of 967 men and 808 women were coded using the German classification of occupation. Hypertension was defined as blood pressure of ≥140 mmHg (systolic), ≥90 mmHg (diastolic) or use of antihypertensives. Sex-stratified, age-adjusted prevalence risk ratios (PR) with 95% confidence intervals (CI) were calculated for 31 occupational groups.

RESULTS

Hypertension was prevalent in 79% of the population. In men, highest age-adjusted prevalence ratios were observed in metal-processing workers, carpenters/painters, and electricians with PRs of 1.31 (CI 1.04-1.65), 1.28 (CI 1.00-1.64), and 1.21 (0.95-1.53), respectively, compared to office clerks. In women, highest PRs were found in technicians/forewomen, scrutinisers/storekeepers, and food-processing occupations with PR 1.28 (1.09-1.49), 1.23 (0.99-1.51), and 1.22 (1.01-1.48), respectively. Adjustment for education, smoking, body mass index, and current work hours did not fully explain occupational differences. Excluding currently non-working subjects lead to decreased PRs in men and to increased PR in women.

CONCLUSIONS

Differences in the prevalences of hypertension by occupational group were only partly explained by conventional risk factors and may require workplace interventions targeted at high-risk occupations. Longitudinal data with large cohorts and work-related exposure assessment are needed to confirm a temporal relationship between occupation and incident hypertension.

[Dithiols as chelators. A cause of bullous skin reactions]

Chelation therapy with (RS)-2,3-Bis(sulfonyl)propane-1-sulfonic acid (DMPS) after an occupational lead exposure led to the development of a severe bullous drug eruption. Skin tests and histology/immunohistology of the test reactions indicated a T-cell-mediated immune response against DMPS. Metal-binding thiol groups as in DMPS are chemically highly reactive and therefore effectively mediate the development of immunogenic hapten (DMPS)-protein complexes. Therefore, the pharmacological effects and sensitization potential of dithiols are tightly connected. Cross-reactivity of DMPS to other chelators like D-penicillamine is possible; the indications for chelation therapy should be weighed carefully.

Lead and arsenic levels in women with different body mass composition

The objective of this study was to evaluate whether lead (Pb) and arsenic (As) levels in biological fluids were associated to the body composition in a group of reproductive-age women. Voluntary childbearing-age women (n = 107) were divided into three groups according to their body mass index (BMI: weight/height(2) (kg/m(2)): low weight (BMI<18.5 kg/m(2)), normal (BMI > 19 < 24·9 kg/m²), and overweight (BMI>25 kg/m(2)). Body composition and fat mass percentage were determined by the isotopic dilution method utilizing deuterated water. Blood lead concentrations were determined by graphite furnace atomic absorption spectrometry and urinary arsenic (AsU) concentrations by inductively coupled plasma mass spectrometry. The type and frequency of food consumption and lifestyle-related factors were also registered. Most women had PbB levels > 2 < 10μ g/dl, and only 2.6% had AsU concentrations above 50 microg/L. The levels of these toxic elements were not found to be associated with the fat mass percentage.

Trace element status in hemodialysis patients

Patients with chronic kidney disease undergoing hemodialysis (HD) are potentially at risk of deficiency and excess of trace elements. HD exposes patients to large volumes of water (>120 l/week) in the form of dialysate. Although levels of certain ions (such as potassium and calcium) are carefully regulated in dialysate, many others are measured infrequently, if ever. As a result, substances in lower concentrations in the dialysis may be leached from the body. Conversely, toxic trace elements present in water but not in blood may accumulate and cause toxicity. Given that essential trace elements play key roles in multiple biological systems including immunological defense against oxidation and infection, it has been hypothesized that the increased morbidity and mortality seen in HD patients may in part be due to the imbalance of trace elements that has not been recognized. A recent systematic review has shown that compared with healthy controls, HD patients have significantly lower blood levels of zinc, manganese, and selenium, while blood levels of lead are likely to accumulate. Other trace elements, such as mercury and arsenic, are biologically plausible causes of excess mortality in dialysis patients, but available evidence is inconclusive as to whether they consistently accumulate in this population. Whether altered trace element levels are potentially reversible causes of adverse clinical outcomes in dialysis patients remains to be determined. This review highlights key issues related to this hypothesis, with special emphasis on zinc, manganese, selenium, lead, mercury, and arsenic.

Biomarkers of lead exposure and DNA methylation within retrotransposons

BACKGROUND

DNA methylation is an epigenetic mark that regulates gene expression. Changes in DNA methylation within white blood cells may result from cumulative exposure to environmental metals such as lead. Bone lead, a marker of cumulative exposure, may therefore better predict DNA methylation than does blood lead.

OBJECTIVE

In this study we compared associations between lead biomarkers and DNA methylation.

METHODS

We measured global methylation in participants of the Normative Aging Study (all men) who had archived DNA samples. We measured patella and tibia lead levels by K-X-Ray fluorescence and blood lead by atomic absorption spectrophotometry. DNA samples from blood were used to determine global methylation averages within CpG islands of long interspersed nuclear elements-1 (LINE-1) and Alu retrotransposons. A mixed-effects model using repeated measures of Alu or LINE-1 as the dependent variable and blood/bone lead (tibia or patella in separate models) as the primary exposure marker was fit to the data.

RESULTS

Overall mean global methylation (+/- SD) was 26.3 +/- 1.0 as measured by Alu and 76.8 +/- 1.9 as measured by LINE-1. In the mixed-effects model, patella lead levels were inversely associated with LINE-1 (beta = -0.25; p < 0.01) but not Alu (beta = -0.03; p = 0.4). Tibia lead and blood lead did not predict global methylation for either Alu or LINE-1.

CONCLUSION

Patella lead levels predicted reduced global DNA methylation within LINE-1 elements. The association between lead exposure and LINE-1 DNA methylation may have implications for the mechanisms of action of lead on health outcomes, and also suggests that changes in DNA methylation may represent a biomarker of past lead exposure.

A population-based assessment of blood lead levels in relation to inflammation

BACKGROUND

Some experimental and observational research suggests that inflammation may be an important mediator of lead toxicity. However, lead-induced inflammation has not been well-studied in non-occupationally exposed populations.

METHODS

Using data for 9,145 individuals >or=40 years of age from the National Health and Nutrition Examination Survey 1999-2004, we assessed the association between blood lead levels (BLLs) and C-reactive protein (CRP), fibrinogen, and white blood cell (WBC) count via ordinal logistic regression. We also examined the interaction between BLL and gender in relation to the inflammatory markers.

RESULTS

No evidence for an association between lead exposure and inflammatory markers was observed with odds ratios around or below the null. Although men but not women appeared to be at increased risk of lead-induced inflammation, no consistent dose-response patterns were observed across BLL quintiles.

CONCLUSION

Inflammation does not appear to be an important mediator of lead toxicity.

Modification by ALAD of the association between blood lead and blood pressure in the U.S. population: results from the Third National Health and Nutrition Examination Survey

BACKGROUND

Environmental lead exposure has been found to be associated with an increased risk of hypertension. Individuals vary greatly in susceptibility to lead toxicity, and genetic susceptibility has often been cited as the probable cause for such variation.

OBJECTIVE

The main objective is to determine the role of the aminolevulinic acid dehydratase (ALAD) gene, which encodes the main carrier protein of lead in blood, in the association between lead exposure and blood pressure (BP) and hypertension in the U.S. population.

METHODS

We analyzed data from individuals >or= 17 years of age who participated in the Third National Health and Nutrition Examination Survey for whom DNA was available (n = 6,016). Multivariable logistic and linear regressions stratified by race/ethnicity were used to examine whether hypertension and BP were associated with ALAD and blood lead levels (BLL).

RESULTS

BLL was associated with systolic BP in non-Hispanic whites and with hypertension and systolic and diastolic BP in non-Hispanic blacks. BLL was not associated with BP outcomes in Mexican Americans. Non-Hispanic white ALAD2 carriers in the highest BLL quartile (3.852.9 microg/dL) had a significantly higher adjusted prevalence odds ratio for hypertension compared with ALAD1 homozygous individuals. We also found a significant interaction between lead concentration and the ALAD2 allele in non-Hispanic whites and non-Hispanic blacks in relation to systolic BP.

CONCLUSIONS

BLL may be an important risk factor for hypertension and increased systolic and diastolic BP. These associations may be modified by ALAD genotype.

Influence of lead acetate on glutathione and its related enzymes in different regions of rat brain

This study is intended to determine the effect of lead acetate on glutathione and its associated enzymes of rat brain. Wistar male rats were treated with lead acetate (500 ppm) through drinking water for a period of 8 weeks and parallel controls were maintained. They were sacrificed at the first, fourth and eighth week to isolate whole brains, which were separated into cerebellum, hippocampus, frontal cortex and brain stem. The data indicate enhanced (P < 0.05) glutathione peroxidase (G-Px) activity at most of the intervals for cerebellum, frontal cortex and brain stem, suggesting conversion of GSH to GSSG, while the hippocampus showed decreased levels. In contrast, glutathione reductase (GR) decreased significantly (P < 0.05) in cerebellum, frontal cortex and brain stem at all intervals except the fourth week in frontal cortex and brain stem. Hippocampus exhibited a gradual and significant (P < 0.05) increase in GR activity. Glutathione-S-transferase (GSTase) activity increased with exposure time in all four brain tissues, showing protection against lead acetate toxicity. The GSH and GSSG levels correlated well with the activities of GPx, GR and GSTase in all four regions of the brain. Overall the results indicate that lead acetate affects glutathione-related enzymes differentially and these changes can be attributed to differences in tissue susceptibility.

Fugitive dust and human exposure to heavy metals around the Red Dog Mine

Fugitive dust from the Red Dog Mine is a potential source of exposure to heavy metals for residents of the surrounding area. Possible pathways of exposure include direct inhalation of particles, dermal contact with or ingestion of contaminated soils, residential exposure of individuals who have close association with mine workers, and subsistence activities. Study results indicate that soils and mosses close to the haul road are contaminated with dust and metals from hauling activities. However, investigations of exposure from subsistence activities performed near Red Dog Mine do not indicate that human health has been negatively affected by metal contamination. Epidemiological studies of nearby village residents do not show blood lead levels that exceed the CDC level of concern for children. The mine currently uses several control practices to reduce dust and control human dust and metal exposure. Nonetheless, the potential for human health impairment will persist throughout the life of the mine and beyond. Sound environmental management and monitoring of human health should remain a priority for the Red Dog Mine and for agencies that provide regulatory oversight to the mine.

Lead exposure stimulates VEGF expression in the spinal cord and extends survival in a mouse model of ALS

Exposure to environmental lead (Pb) is a mild risk factor for amyotrophic lateral sclerosis (ALS), a paralytic disease characterized by progressive degeneration of motor neurons. However, recent evidence has paradoxically linked higher Pb levels in ALS patients with longer survival. We investigated the effects of low-level Pb exposure on survival of mice expressing the ALS-linked superoxide dismutase-1 G93A mutation (SOD1(G93A)). SOD1(G93A) mice exposed to Pb showed longer survival and increased expression of VEGF in the ventral horn associated with reduced astrocytosis. Pretreatment of cultured SOD1(G93A) astrocytes with low, non toxic Pb concentrations upregulated VEGF expression and significantly abrogated motor neuron loss in coculture, an effect prevented by neutralizing antibodies to VEGF. The actions of Pb on astrocytes might explain its paradoxical slowing of disease progression in SOD1(G93A) mice and the improved survival of ALS patients. Understanding how Pb stimulates astrocytic VEGF production and reduces neuroinflammation may yield a new therapeutic approach for treating ALS.

Use of oral dimercaptosuccinic acid (succimer) in adult patients with inorganic lead poisoning

BACKGROUND

Chelation therapy has been used as a means of reducing the body burden of lead for five decades. Intravenous sodium calcium edetate has been the preferred agent, but there is increasing evidence that dimercaptosuccinic acid (DMSA) is also a potent chelator of lead.

METHODS

Oral DMSA 30 mg/kg/day was administered to adults with blood lead concentrations > or = 50 microg/dl. The impact of DMSA on urine lead excretion, on blood lead concentrations and on symptoms was observed. The incidence and severity of adverse effects was also recorded.

RESULTS

Thirty-five courses were given to 17 patients. DMSA significantly (P < 0.0001) increased urine lead excretion and significantly (P < 0.0001) reduced blood lead concentrations. Mean daily urine lead excretion exceeded the pre-treatment value by a median of 12-fold with wide variation in response (IQR 8.9-14.8, 95% CI 10.1-14.6). Pre-treatment blood lead concentrations correlated well with 5-day urine lead excretion. Headache, lethargy and constipation improved or resolved in over half the patients within the first 2 days of chelation. DMSA was generally well tolerated, but one course was discontinued due to a severe mucocutaneous reaction. There was a transient increase in alanine aminotransferase (ALT) activity during 14% of chelations. DMSA caused a significant increase in urine copper (P < 0.0001) and zinc (P < 0.05) excretion.

CONCLUSION

Oral DMSA 30 mg/kg/day is an effective antidote for lead poisoning, though there is a wide inter- and intra-individual variation in response.

Pb2+: an endocrine disruptor in Drosophila?

Environmental exposure to Pb(2+) affects hormone-mediated responses in vertebrates. To help establish the fruit fly, Drosophila melanogaster, as a model system for studying such disruption, we describe effects of Pb(2+) on hormonally regulated traits. These include duration of development, longevity, females' willingness to mate, fecundity and adult locomotor activity. Developmental Pb(2+) exposure has been shown to affect gene expression in a specific region of the Drosophila genome (approximately 122 genes) involved in lead-induced changes in adult locomotion and to affect regulation of intracellular calcium levels associated with neuronal activity at identified synapses in the larval neuromuscular junction. We suggest ways in which Drosophila could become a new model system for the study of endocrine disruptors at genetic, neural and behavioral levels of analysis, particularly by use of genomic methods. This will facilitate efforts to distinguish between behavioral effects of Pb(2+) caused by direct action on neural mechanisms versus effects of Pb(+2) on behavior mediated through endocrine disruption.