A review of persistent, low-grade lead challenge: neurological and cardiovascular consequences

A systematic review of fish adulteration and contamination in Bangladesh: A way forward to food safety

For decades, the world has been plagued by widespread food adulteration, and Bangladesh is no exception. Dishonest business people and fish farmers unlawfully utilize various preservatives to avoid rotting and extend the shelf life of fish. Although previous research has examined the level of formalin use in fish bodies, no studies focusing on all aspects of fish adulteration and contamination in Bangladesh have been carried out. In this context, the aim of this review is to explore the extent and magnitude of illegal fish adulteration and contamination in Bangladesh. Among the 37 reviewed studies, 11 of them highlighted formalin adulteration in fish samples and fish feed. The extent of formalin use varied between local and imported fish, and between large and small fish. Imported and large fish were substantially more formalin‐contaminated. Several investigations have discovered that antibiotic levels in farm water and fish feed exceed the permitted level. Farmers have used growth promoters incautiously. This study also identifies that certain metal substances, such as chromium, lead, arsenic, cadmium, iron, mercury and cobalt, have been frequently found in fish bodies and feed samples. Furthermore, a distinct type of fish adulteration caused by aromatic compounds has emerged recently. The findings and their ramifications are extremely concerning for human lives. However, since each study employed a different testing kit, the results were quite distinct. Thus, the adoption of a precise and sensitive kit is strongly recommended. The government should make it a top priority to solve the problem of fish adulteration by implementing appropriate food safety laws and policies.

Inorganic Lead Toxicology

Lead is a health hazard for all humans. Especially children under the age of six are most at risk for lead poisoning. Lead toxicity causes hematological, gastrointestinal, and neurological dysfunction. Symptoms are usually noted with blood lead greater than 2 micromoles/L. Severe or prolonged exposure may also cause chronic nephropathy, hypertension, and reproductive impairment. Lead inhibits some enzymes, alters cellular calcium metabolism, stimulates synthesis of binding proteins in kidney, brain, and bone, and slows down nerve conduction. Acute lead poisoning is relatively infrequent and results from ingestion of acid soluble lead compounds or inhalation of lead vapors but chronic exposure to low levels of the metal is still a public health issue, especially among some minorities and socioeconomically disadvantaged groups. Lead has been used since prehistoric times, and has become widely distributed and mobilized in the environment. Exposure to and uptake of this non-essential element have consequently increased. Both occupational and environmental exposures to lead remain a serious problem in many developing and industrializing countries and a public health problem of global dimensions.

One-step synthesis of a dual-emitting carbon dot-based ratiometric fluorescent probe for the visual assay of Pb2+ and PPi and development of a paper sensor

Herein, an easy and effective ratiometric fluorescent nanoprobe for the selective detection of Pb²⁺ and pyrophosphate (PPi) was developed based on label-free carbon dots (CDs).

Determination of Pb (Lead), Cd (Cadmium), Cr (Chromium), Cu (Copper), and Ni (Nickel) in Chinese tea with high-resolution continuum source graphite furnace atomic absorption spectrometry

The contents of lead, cadmium, chromium, copper, and nickel were determined in 25 tea samples from China, including green, yellow, white, oolong, black, Pu’er, and jasmine tea products, using high-resolution continuum source graphite furnace atomic absorption spectrometry. The methods used for sample preparation, digestion, and quantificational analysis were established, generating satisfactory analytical precisions (represented by relative standard deviations ranging from 0.6% to 2.5%) and recoveries (98.91–101.32%). The lead contents in tea leaves were 0.48–10.57 mg/kg, and 80% of these values were below the maximum values stated by the guidelines in China. The contents of cadmium and chromium ranged from 0.01 mg/kg to 0.39 mg/kg and from 0.27 mg/kg to 2.45 mg/kg, respectively, remaining in compliance with the limits stipulated by China’s Ministry of Agriculture. The copper contents were 7.73–63.71 mg/kg; only 64% of these values complied with the standards stipulated by the Ministry of Agriculture. The nickel contents ranged from 2.70 mg/kg to 13.41 mg/kg. Consequently, more attention must be paid to the risks of heavy metal contamination in tea. The quantitative method established in this work lays a foundation for preventing heavy metal toxicity in human from drinking tea and will help establish regulations to control the contents of heavy metals in tea.

Lead and essential trace element levels in school children: a cross-sectional study

BACKGROUND

Nutritional status is thought to modulate susceptibility to lead (Pb) toxicity. The type and nature of these interactions needs to be investigated.

AIM

To assess the prevalence of sub-clinical Pb toxicity (defined by ≥ 10 μ_rm;g/dL blood levels) and trace element deficiencies (Iron (Fe), Zinc (Zn), Copper (Cu) and Magnesium (Mg)) and to find out their possible relationship, if any.

SUBJECTS AND METHODS

A cross-sectional survey was carried out in a total of 195 school children residing in urban (n = 65), urban heavy traffic (n = 65) and urban industrial (n = 65) zones of Hyderabad, India. Blood Pb, trace element levels, haemoglobin and δ-aminolevulinate dehydratase (δ-ALAD) activity was measured.

RESULTS

High blood lead levels ( ≥ 10 μ_rm;g/dL) were observed in 54.3% of children while percentage prevalence of trace element deficiencies such as Fe (16.2%), Zn (68.6%), Mg (41.7%) and Cu (25%) were also high in children included in the study. Higher blood Pb levels and reduced δ-ALAD activity was observed in children residing in heavy traffic and industrial areas. Blood Pb levels but not δ-ALAD activity correlated inversely with serum Fe in heavy traffic and industrial children, respectively. Interestingly, δ-ALAD activity but not blood Pb levels correlated inversely with trace element levels only in urban children.

CONCLUSIONS

These results suggest higher prevalence of sub-clinical Pb toxicity and trace element deficiencies in urban children. Further, high blood Pb levels appear to be correlated with reduced δ-ALAD activity and iron status in Pb exposed children.

Thiamine reduces tissue lead levels in rats: mechanism of interaction

Lead (Pb) toxicity has been a serious concern in industrialized societies because of its association with functional deficits in nervous, haematopoietic and renal systems. Several studies have shown beneficial effects of thiamine on Pb toxicity. It is speculated that Pb chelation by thiamine may be a possible mechanism. However, the exact nature of these interactions remained elusive. In the present study we have characterized the interaction of Pb with thiamine using UV-Vis as well as fluorescence spectroscopic methods and studied the effect of thiamine treatment on blood and tissue Pb levels during simultaneous or post-exposure to Pb in rat model. The spectroscopic studies revealed that Pb interacts with the pyrimidine ring of thiamine, leading to its solubilization at physiological pH. Further, thiamine reduced the Pb levels in blood, kidney and bone during both simultaneous and post-exposure Pb treatment. Interestingly, thiamine appears to prevent the accumulation of Pb in bone during simultaneous treatment. Together these results suggest that pyrimidine ring of thiamine mediates its interaction with Pb, leading to the prevention of its accumulation and/or increased clearance from tissues.

Blood lead level and blood pressure of bus drivers in Bangkok, Thailand

This study aims to evaluate blood lead level (PbB) and blood pressure of bus drivers in Bangkok, Thailand, after the phasing out of lead in gasoline. The subjects comprised of 439 male bus drivers whose age ranged between 23 and 59 yr with the mean age of 42 +/- 8 yr. Average working experience was 10 +/- 7 yr. The mean of the systolic and diastolic blood pressure were 131 +/- 17 and 81 +/- 11 mmHg, respectively. PbB ranged from 2.5 to 16.2 microg/dl with the mean PbB of 6.3 microg/dl. Prevalence rate of systolic and diastolic hypertension among bus drivers were 23.0% and 18.2%, respectively. There were significant correlations between PbB and blood pressure both in systolic and diastolic blood pressure after controlling for age, BMI, alcohol consumption, smoking and physical exercise. However, the data on psycho-social factors which may affect on blood pressure of bus drivers were not available. Therefore, further study is needed to clarify the relationship between blood pressure and psycho-social stress among bus drivers in Bangkok. These findings suggested lead exposure at low PbB is related to increases in blood pressure.

Metals in cigarette smoke

Metals are vital for a huge number of physiological processes in the human body, but can also destroy health when the concentration is not within the physiologically favourable range. Cigarette smoking interferes with the carefully controlled metal homeostasis of the human body. This review focuses on the consequences of metal delivery to the human body by cigarette smoking and discusses the body's responses. The metal content of tobacco plants, smoke, the circulation, and various organs is discussed. Finally, we link individual cigarette smoke contained metals to the genesis of human diseases.

Effects of acute and chronic oval exposure of lead on blood pressure and bone mineral density in rats

The immediate and late deleterious effects of early lead (Pb) exposure on human health are major challenges to the health professionals. Therefore, a major underlying contribution of Pb accumulated earlier in life to chronic disorders such as hypertension and osteopenia, commonly found in the elderly, cannot be definitively excluded. Using Sprague-Dawley rats, we examined the effects of drinking 1% Pb acetate on very young rats for 40 days on Pb kinetics, body weight (BW), systolic blood pressure (SBP) and bone mineral density (BMD) over a year-long period. We also examined the effects of early and later chelation using disodium calcium ethylenediaminetetraacetate (Na2CaEDTA). The early ingestion and accumulation of Pb was associated with an increased SBP acutely that returned to control levels with continuing challenge and later rose above control months later after the Pb challenge had been halted. Early accumulation of Pb over a short period was also associated with decreased BMD at the end of one year. Chelation after the initial Pb challenge at various times favorably influenced the SBP but could not prevent the lowering of BMD.

Bone lead and blood lead levels in relation to baseline blood pressure and the prospective development of hypertension: the Normative Aging Study

Between 1991 and 1997, the authors studied 833 participants of the Normative Aging Study in a substudy of bone lead levels (measured by K-shell x-ray fluorescence), blood lead levels, and hypertension. Among these subjects, 337 were classified as normotensive, and 182 and 314 were classified as having borderline and definite hypertension, respectively, at baseline. These bone and blood lead levels were typical of those of community-exposed men. Among the 519 subjects with no history of definite hypertension at baseline, cross-sectional analyses revealed positive associations between systolic blood pressure and bone lead levels. Of the 474 subjects who were free from definite hypertension at baseline and had follow-up data, 74 new cases of definite hypertension were reported. Baseline bone lead levels were positively associated with incidence of hypertension. In proportional hazards models that controlled for age, age squared, body mass index, and family history of hypertension, an increase in patella (trabecular) lead from the midpoint of the lowest quintile to that of the highest quintile was associated with a rate ratio of definite hypertension of 1.71 (95% confidence interval: 1.08, 2.70). No association was found with blood lead level. These results support the hypothesis that cumulative exposure to lead, even at low levels sustained by the general population, may increase the risk of hypertension.

Reappraisal of the relation between blood lead concentration and blood pressure among the general population in Taiwan

OBJECTIVES

The relation between blood lead concentration (PbB) and blood pressure was examined in a Taiwan nationwide population survey of PbB from July 1993 to June 1994.

METHODS

After multistage sampling procedures, 2800 subjects (1471 males and 1329 females) with a mean (range) age of 44 (15-85) years were enrolled in this study. Anthropometric, blood pressure, and lifestyle factors were measured during household visits. The PbB was measured with a flameless atomic absorption spectrophotometer and all specimens were analysed in triplicate.

RESULTS

The mean (range) PbB among all study subjects was 6.5 (0.1-69.1) micrograms/dl; among males it was 7.3 (0.1-69.1) micrograms/dl and among females 5.7 (0.1-40.1) micrograms/dl). The mean (range) systolic blood pressure among all subjects was 123 (80-210) mm Hg, among males it was 127 (80-200) mm Hg and among females 119 (80-210) mm Hg. The diastolic blood pressure among all subjects was 78 (40-150) mm Hg; among males it was 80 (40-130) mm Hg; and among females 75 (40-150) mm Hg. Age, body height, body weight, and body mass index (BMI) were significantly correlated with systolic blood pressure or diastolic blood pressure in both sexes. The PbB (or the natural logarithmic transformed PbB) was not significantly correlated with blood pressure among males or females. After adjustment for the potential confounders of age, age2, BMI, milk intake, alcohol consumption, and cigarette smoking, systolic blood pressure was significantly associated with PbB among males with a regression coefficient (beta) of 0.185 (p = 0.015). No significant association between PbB and blood pressure was found among females.

CONCLUSIONS

From this study, only a weak association between systolic blood pressure and PbB was found among males. There was no strong evidence that PbB was a good predictor of blood pressure. However, the possibility that long term high body lead burden could cause high blood pressure could not be ruled out on the basis of this survey.

Risk factors for high blood lead levels among the general population in Taiwan

PURPOSE

Environmental and occupational lead pollution is a common problem in both developing and industrialized countries. The purpose of this study is to evaluate the risk factors for high blood lead levels among the general population in Taiwan.

METHODS

After multi-stage sampling, we randomly selected 2803 subjects (1471 males and 1332 females) for this study. Univariate and multivariate logistic regression analyses were conducted to evaluate the risk of high blood lead. To control for differences in age and gender, all analyses were with age-adjusted and gender-stratified.

RESULTS

Among males, the mean age is 46 years (15 to 85 years), mean and median blood lead levels is 7.3 and 6.3 microg/dl, respectively. Among females, the mean age is 43 years (15 to 84 years), mean and median blood lead level is 5.7 and 4.8 microg/dl, respectively. Among males, the history of herbal drug use, drinking water from well or spring sources, and occupational lead exposure are significantly different between relatively high and normal blood lead level subjects. The history of occupational lead exposure, history of herbal drug use, and well or spring sources of drinking water are the major risk factors for high blood lead with odds ratio of 4.62 (95% CI: 2.82-7.55), 3.09 (95% CI: 1.60-5.97), 2.06 (95% CI: 1.13-3.76), and 2.37 (95% CI: 1.39-4.04), respectively. Among females, these characteristics remain important except the sources of drinking water. The history of herbal drug use and occupational lead exposure become the major risk factors for high blood lead with odds ratio of 2.94 (95% CI: 1.26-6.88) and 7.72 (95% CI: 3.51-16.99), respectively. In multivariate logistic regression analyses, we find that the risk factors for high blood lead in both genders include a history of herbal drug use and occupational lead exposure. Among males, the drinking water sources and factories in the neighboring areas are also significant factors for high blood lead.

CONCLUSIONS

For the goal of reducing prevalence of high blood lead by the year 2000, the improvement and monitoring of the working environment, the careful attention to herbal drug use and the lead-free drinking water sources should be executed as thoroughly as possible to reduce the probability of lead pollution.

Lead consumption of 18- to 36-month-old children as determined from duplicate diet collections: nutrient intakes, blood lead levels, and effects on growth

OBJECTIVE

To determine the amount of lead ingested in food by means of duplicate diet collections, nutrient intakes, and anthropometric measurements of young children.

DESIGN

Once a month for a year, data were collected from 24-hour duplicate diets, hand wipes, a dust index, and anthropometric measurements. Quarterly, venous blood samples were obtained. Thermal ionization spectrometry by means of a lead-205 tracer was used to determine lead present in food, blood, and the hand wipes. A dust index was determined on the basis of observation of dust on surfaces in the home. Anthropometric measurements obtained were height, weight, head circumference, and mid-upper arm circumference.

SUBJECTS/SETTING

Subjects were 21 children, aged 18 to 36 months, who resided in homes located in an urban area with potentially high lead levels.

MAIN OUTCOMES MEASURED

Lead contamination in food and on hands, and blood lead values, were determined.

STATISTICAL ANALYSIS PERFORMED

Pearson correlation coefficients were used to determine relationships between lead content in food, blood, and hand wipes and growth. Multiple regression analyses examined the effect of food types and dust lead on lead levels in food, and the effect of these variables on head circumference.

RESULTS

Mean blood levels were 0.3089 +/- 0.1496 micromol/L; 12 samples contained more than 0.4826 micromol/L. Total intake of lead from food was 4.95 microg/day and ranged from 1.10 to -22.10 microg/day. More than a fourth of the diets collected exceeded 6.00 microg/day. Foods considered home prepared were moderately related to blood lead level, and the dust index and hand wipe lead levels were related to total food lead. Home-handled foods, canned foods, and hand-wipe lead were significant predictors of the lead content in food. A negative relationship was found between head circumference and blood lead level.

APPLICATIONS

Level of lead in food was directly related to hand-wipe lead. This finding underscores the need for dietitians and other health professionals to stress the importance of cleanliness in environments that are potentially lead contaminated. Appropriate hand washing and surface cleaning should be emphasized when preparing and consuming food. The inverse relationship between head circumference and blood lead levels points to the need for additional studies to validate this finding while controlling for other extraneous variables.

Obtaining information about susceptibility from the epidemiological literature

Whether people become ill after encountering environmental pollutants depends on the magnitude of their exposure and their capacity to respond. Exposure and intrinsic response capabilities vary within the population. Those that become ill when the general population remains largely unaffected are considered to be highly susceptible. The U.S. Environmental Protection Agency (USEPA), responsible for protecting the public from environmental pollutants, has developed risk assessment procedures to assist in evaluating the likelihood of health effects. However, the Agency's ability to evaluate the risk faced by highly susceptible populations is often hindered by the paucity of adequate health effects data. Response variability can be assessed with animal models and human epidemiological studies. Although animal models are useful when evaluating the effect of gender and developmental stage on susceptibility, inbred rodent strains underestimate the genetic and lifestyle-induced variability in susceptibility found in human populations. Epidemiological approaches are the preferred source of information on variability. This paper reviews the epidemiological literature from the perspective of a risk assessor seeking data suitable for estimating the risk to highly susceptible populations. Epidemiological approaches do not measure the full range of population response variability. Rather, "susceptibility factors" are evaluated either as risk factors or by focusing on the susceptible population, e.g. children. Susceptibility factors due to genetics, developmental stage, gender, ethnicity, disease state and lifestyle are most frequently encountered. Often, the information describing the health impact of the susceptibility factor is incomplete due to, (1) a failure to consider factors modifying susceptibility; (2) inadequate exposure data; (3) a failure to evaluate the health impact of the susceptibility factor. In addition, for a given exposure agent, several susceptibility factors may be relevant. While incomplete data describing susceptibility factors limits the opportunity for quantitative estimations of risk, available information can supplement qualitative evaluations and risk management.

Cardiovascular Effects of Environmental Chemicals

This article presents recent data on several environmental toxins: lead, carbon disulfide, asbestos, arsenic, ozone, cadmium, vinyl chloride, fiuorocarbons, freon, and pesticides. These environmental toxins produce both hypertension and cardiac arrhythmias in most studies, and they are not necessarily related to primary lung disease and secondary heart disease. The possible mechanisms that could cause the cardiovascular diseases include (1) damage to the endothelial barrier in the vascular system, (2) activation of leukocytes and platelets, (3) initiation of plaque formation, (4) stimulation of the inflammatory response, (5) kidney-related hypertension, and (6) direct damage to cardiac and blood vessel tissue. Recommendations are that more animal, human cultured cell, and epidemiologic studies should be conducted on the environmental toxins identified in this article.