Exposure to toxic elements via breast milk

Total mercury concentrations in Steller sea lion bone: Variability among locations and elements

Mercury is a global contaminant that bioaccumulates in a tissue-specific manner in long-lived predators such as Steller sea lions (SSL). Bone is a well-preserved material amenable for studying millennial scale trends; however, little is known about the distribution and variability of total mercury concentrations ([THg]) within individual bones and among bone elements in SSL. We assessed SSL bone [THg] variability with respect to physiologic age, bone type, longitudinally within a bone, and among bone elements. Pup bones (mean ± SD; 31.4 ± 13.58 ppb) had greater [THg] than adults (7.9 ± 1.91 ppb). There were greater and more variable [THg] within individual long bones near epiphyses compared to mid-diaphysis. Pup spongy bone in ribs (62.7 ± 44.79 ppb) had greater [THg] than long bones (23.5 ± 8.83 ppb) and phalanges (19.6 ± 10.78 ppb). These differences are likely due to variability in bone composition, growth, and turnover rate. This study informs standardized sampling procedures for [THg] in bone to improve interpretations of mercury variability over time and space.

Assessment of Soil Heavy Metal Pollution and Health Risks in Different Functional Areas on the Northern Slope of the Eastern Tianshan Mountains in Xinjiang, NW China

In typical semi-arid areas, the timely and effective monitoring and evaluation of soil heavy metal pollution are of critical importance to prevent soil deterioration and achieve the sustainable use of soil resources. To further understand the degree of soil heavy metal pollution in different functional areas, we studied the soil heavy metal pollution on the northern slope of the eastern Tianshan Mountains in Xinjiang. We collected 104 surface soil samples from typical commercial (A), industrial (B), and agricultural (C) areas with different land-use patterns. The contents of Zn, Cu, Cr, Pb, As, and Hg in the soil of different functional areas were evaluated using the geo-accumulation index, the single-factor pollution index, and potential ecological risk. The results showed that the contents of Pb, As, and Hg in soils of different functional areas exceeded 4.47, 8.03, and 1.5 times the background values of Xinjiang soil, respectively. The average contents of Zn, Cu, and Cr were lower than the background values of Xinjiang soil. Except for As in different functional areas, the contents of the other elements in the different functional areas reached the level of soil environmental quality standards in China (GB15618-2018). The geo-accumulation index of heavy metals in different functional areas was in the order of Area C > Area A > Area B, indicating that Area C was the most polluted. The results of the single-factor pollution index showed that the pollution levels of Pb, As, and Hg were higher, and the pollution levels of Cr, Cu, and Zn were lower. The results of the potential ecological risk index showed that the northwest of Area A was higher, the southeast of Area B was more polluted, and the central and eastern parts of Area C were more polluted. From the perspective of spatial distribution, the spatial distribution characteristics of Zn and Cr elements in different functional areas are consistent, but the spatial distribution characteristics of Cu, Pb, As, and Hg in different functional areas are quite different. The high values of these four elements are mainly distributed in residential areas, factories, and metal smelters. It is necessary to divide the functional areas based on different land-use patterns, and the prevention of soil single-element and heavy metal pollution in different functional areas is reasonable for land resources and provides a scientific basis for the effective planning of quality assurance.

Perspective: Human Milk Composition and Related Data for National Health and Nutrition Monitoring and Related Research

National health and nutrition monitoring is an important federal effort in the United States and Canada, and the basis for many of their nutrition and health policies. Understanding of child exposures through human milk (HM) remains out of reach due to lack of current and representative data on HM's composition and intake volume. This article provides an overview of the current national health and nutrition monitoring activities for HM-fed children, HM composition (HMC) and volume data used for exposure assessment, categories of potential measures in HM, and associated variability factors. In this Perspective, we advocate for a framework for collection and reporting of HMC data for national health and nutrition monitoring and programmatic needs, including a shared vision for a publicly available Human Milk Composition Data Repository (HMCD-R) to include essential metadata associated with HMC. HMCD-R can provide a central, integrated platform for researchers and public health officials for compiling, evaluating, and sharing HMC data. The compiled compositional and metadata in HMCD-R would provide pertinent measures of central tendency and variability and allow use of modeling techniques to approximate compositional profiles for subgroups, providing more accurate exposure assessments for purposes of monitoring and surveillance. HMC and related metadata could facilitate understanding the complexity and variability of HM composition, provide crucial data for assessment of infant and maternal nutritional needs, and inform public health policies, food and nutrition programs, and clinical practice guidelines.

Toxic metal and trace element status in the breast milk of Turkish new-born mothers

BACKGROUND AND AIM

This study aims to evaluate the toxic metal and trace element concentrations in breast milk obtained from new-born nursing mothers in rural Giresun province, located on the coast of the Black Sea.

METHODS

Milk samples were randomly collected once from early lactation of 50 nursing mothers. Inductively coupled plasma mass spectrometry was used to analyse the concentrations of iron (Fe), nickel (Ni), manganese (Mn), cobalt (Co), chromium (Cr), copper (Cu), zinc (Zn), arsenic (As), molybdenum (Mo), cadmium (Cd) and lead (Pb) in the breast milk. Shapiro-Wilk test was used to evaluate the distribution of data. The Pearson-J correlation was used for normally distributed elements, and Spearman correlation analysis was used for others.

RESULTS

The mean amounts of elements were 3.36 µg kg^-1 of Cr, 9.26 µg kg^-1 of Mn, 797 µg kg^-1 of Fe, 1.99 µg kg^-1 of Ni, 5.92 µg kg^-1 of Cu, 379 µg kg^-1 of Zn and 2.23 µg kg^-1 of Pb. Co, As, Mo and Cd concentrations were below the detection limit. A highly significant correlation was found between iron and Nickel in breast milk.

CONCLUSION

Our findings were evaluated in comparison with the WHO data, and whether they were in accordance with the recommended Dietary Reference Intake (DRI) values for 0-6-months-old infants was calculated. Pb levels were similar to those of WHO, while As and Cd were below the measurable limit. Fe, Mn, and Cr concentrations were higher than WHO data, while Co, Ni, Cu and Zn were lower. This research is the first study conducted in this region.

Lead, mercury, and cadmium levels in breast milk and infant hair in the late period of lactation in Ankara, Turkey

Lead (Pb), mercury (Hg), and cadmium (Cd) have known harmful effects on children's well-being. The object of this study was to measure the levels of heavy metals (Pb, Hg, and Cd) in breast milk and infant hair, connected environmental factors, and the impact on infant growth and development at 8 months. Seventy-four breast milk samples and 46 infant hair samples were analyzed. Cd, Pb, and Hg were detected in 99%, 91%, and 87% of breast milk samples, respectively. Cd levels were higher in the hair of infants in extended families, living in older houses and when there was a maternal history of anemia and postpartum anemia. Hg levels in breast milk were higher in Denver II suspicious/abnormal infants than in Denver II normal infants. Further biomonitoring studies and preventive measures should be conducted to minimize exposure to toxic metals in early childhood period.

Heavy Metal Pollution and Soil Quality Assessment under Different Land Uses in the Red Soil Region, Southern China

The influences of different land uses associated with human activities on soil quality and the redistribution of heavy metal in soil have been widely concerned. Surface soil samples were obtained to assess comprehensive soil quality in a typical red soil region of southern China, combining the heavy metal pollution evaluation with fertility evaluation. It can be learned from the results that the overall level of soil fertility was at medium and lower level, and soil heavy metal pollution risk in the study area in a few regions had reached warning line and slight pollution line, and there was a risk of potential pollution. TOPSIS evaluation results showed that the comprehensive soil quality was mainly good quality and moderate quality, accounting for 31.7% and 29.0% of the total land area, respectively. Positive matrix factorization (PMF) model results showed that transportation source contributes a lot in terms of Cd and Pb. As for Cr, natural source contributes 53.8%. In terms of Cu and Zn, agriculture source contributes 50.7% and 38.7%, respectively. In a word, the comprehensive soil quality assessment in red soil region of southern China provides an important basis for the scientific management and sustainable utilization of soil resources.

Heavy metal pollution and associated health risk assessment of urban dust in Riyadh, Saudi Arabia

Depending on their particle size and concentration, heavy metals in urban dust pose a health hazard to humans. This study investigated the total concentration, health risk, integrated pollution load index (IPI), and enrichment factor (EF) of various heavy metals in urban dust at different locations in Riyadh City. Surface dust samples were collected from 50 different residential yards in the north, south, west, east, and central corners of the city and analyzed for cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn). With respect to concentrations heavy metals were in the following order Zn > Cu > Mn > Cr > Ni > Pb > Cd. The EF trends exposed repeated anthropogenic activities were responsible for Mn, Cr, and Ni, while Pb, Zn, and Cu appeared to come from Earth's crust. Since the heavy metal concentrations were lower than the threshold values, children and adults are exposed to lower health risk in investigated area. Also, there are no pollution of heavy metals in the dust with respect to IPI which is less than the critical limit (<1) with the exception of a sampling location in north side of the city with higher IPI showed unhealthy respiration conditions in particular areas. It was concluded that rapid industrialization and urbanization and their concentrations in dust may cause health problems in near future in north side as well as other sides of Riyadh City.

Neurotoxic effects of combined exposures to aluminum and mercury in early life (infancy)

Aluminum and mercury are environmentally ubiquitous. Individually they are both neurotoxic elements with shared neuro-pathogenic pathways: oxidative stress, altered neurotransmission, and disruption of the neuroendocrine and immune systems. In the infant, Al and Hg differ in type of exposure, absorption, distribution (brain access), and metabolism. In environmentally associated exposure (breast milk and infant formulas) their co-occurrences fluctuate randomly, but in Thimerosal-containing vaccines (TCVs) they occur combined in a proprietary ratio; in these cases, low-doses of Thimerosal-ethylmercury (EtHg) and adjuvant-Al present the most widespread binary mixture in less developed countries. Although experimental studies at low doses of the binary Hg and Al mixture are rare, when studied individually they have been shown to affect neurological outcomes negatively. In invitro systems, comparative neurotoxicity between Al and Hg varies in relation to the measured parameters but seems less for Al than for Hg. While neurotoxicity of environmental Hg (mainly fish methyl-Hg, MeHg) is associated with neurobehavioral outcomes in children, environmental Al is not associated, except in certain clinical conditions. Therefore, the issues of their neurotoxic effects (singly or combined) are discussed. In the infant (up to six months) the organic-Hg and Al body burdens from a full TCV schedule are estimated to reach levels higher than that originating from breastfeeding or from high aluminum soy-based formulas. Despite worldwide exposure to both Al and Hg (inorganic Hg, MeHg, and Thimerosal/EtHg), our knowledge on this combined exposure is insufficient to predict their combined neurotoxic effects (and with other co-occurring neurotoxicants).

Association between Female Reproductive Health and Mancozeb: Systematic Review of Experimental Models

Mancozeb is a widely used fungicide approved for use in agriculture in many countries with long persistence in the environment and consequent bioaccumulation in tissues and biological fluids. Despite the large amount of studies published in recent years, the relationship between mancozeb exposure and female reproductive health is not fully elucidated. In order to summarize current evidence on mancozeb exposure and female reproductive disease, we performed a systematic review of literature. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used to make this review. An adapted version of the National Toxicology Program’s Office of Health and Assessment and Translation (OHAT) framework was used to evaluate the risk of bias. Electronic search on two databases (PubMed and Scopus) was used to find experimental studies (in vitro and in vivo) on mancozeb exposure. The database search identified 250 scientific articles, 20 of which met our inclusion criteria. Selected data were then reviewed and summarized in tables. Overall, mancozeb represents a hazard for female reproductive health, with different mechanisms of action. Undoubtedly more experimental and epidemiological studies are required to definitively validate mancozeb as reproductive toxicant.

Vitamins E and C prevent apoptosis of testicular and ovarian tissues following mancozeb exposure in the first-generation mouse pups

The aim of this study was to evaluate the role of apoptosis in the first-generation pups' testicular and ovarian tissue changes following mancozeb (MNZ) administration during intrauterine and lactating periods and also the preventive effect of the co-administration of vitamins E and C on these changes. Naval Medical Research Institute (NMRI) pregnant mice were randomly divided into six groups: control, vehicle, MNZ, vitamin E plus MNZ, vitamin C plus MNZ and vitamins E and C plus MNZ. Administered doses of MNZ and vitamins E and C were 500, 200 and 100 mg/kg of body weight, respectively. These agents were administered to the animals by oral gavage every 2 days. Vitamin treatment was carried out 30 min prior to MNZ administration. Treatment was started on the second day of gestation and continued until weaning. Separated testes and ovaries of animals were prepared for apoptosis detection by terminal deoxynucleotidyl transferase end-labeling (TUNEL) staining. The percentage of TUNEL-positive cells was reported using the 4,6-diamidino-2-phenylindole method. As compared to the control and vehicle groups, MNZ induced a significant increase ( p < 0.001) in the number of TUNEL-positive cells. The administration of both vitamins E and C alone and together significantly ( p < 0.001) prevented the apoptotic impacts of MNZ. The preventive effect of the co-administration of these vitamins on the ovary was greater compared to the single administration of vitamins E ( p < 0.001) or C ( p < 0.001). Meanwhile, the results revealed the stronger preventive effect of vitamin C as compared to E on testicular tissue ( p < 0.05). The apoptotic impact of MNZ exposure during intrauterine and lactating periods on first-generation testicular and ovarian tissues was significant. The co-administration of vitamins E and C could prevent MNZ-induced testicular and ovarian changes.

Sexual Maturity and Life Stage Influences Toxic Metal Accumulation in Croatian Brown Bears

The influence of reproductive and (early) life stages on toxic metal levels was investigated in the brown bear (Ursus arctos), the largest mammalian predator species in Croatia. The purpose was to examine critical clusters in a population that might be at a higher risk of adverse health effects caused by metals as environmental contaminants. Levels of cadmium, mercury and lead in muscle, liver and kidney cortex of 325 male and 139 female bears, quantified by inductively coupled plasma mass spectrometry, were analysed according to distinct bear life stages (young: cub, yearling, subadult; mature: adult). Metal levels did not differ among sexes in young animals (< 4 years), except for mercury in muscles (higher in females), and adult females had higher cadmium and mercury. A trend of renal cadmium accumulation with age in immature male animals disappeared once they reached maturity, whereas for females this trend has only slowly declined in mature compared to immature bears. In early life stage (< 1 year), bear cubs had lower cadmium, comparable mercury, and higher lead in the kidneys than the bears of the following age category (yearlings). Due to a higher proportion of renal lead transfer from the mother to the cub compared with cadmium, it may be that the high burden of cadmium found in kidneys of older females has lower toxicological concern for their cubs than the lead content. Sex, reproductive, and life stages of bears were confirmed as important in assessing toxic metal burden.

Use of human milk in the assessment of toxic metal exposure and essential element status in breastfeeding women and their infants in coastal Croatia

Pregnant and lactating women and infants are vulnerable population groups for adverse effects of toxic metals due to their high nutritional needs and the resultant increased gastrointestinal absorption of both, essential and toxic elements. Although breastfeeding is recommended for infants worldwide, as human milk is the best source of nutrients and other required bioactive factors, it is also a pathway of maternal excretion of toxic substances including toxic metals and thus a source of infant exposure. The aim of this research was to assess health risks in breastfeeding women in the coastal area of the Republic of Croatia and their infants (N=107) due to maternal exposure to Cd and Pb via cigarette smoking, and Hg via seafood and dental amalgam fillings, and their interaction with essential elements. Biological markers of exposure were the concentrations of main toxic metals Pb, Cd and Hg in maternal blood and three types of breast milk throughout lactation stages. Biological markers of effects were the levels of essential elements Ca, Fe, Cu, Zn and Se in maternal serum and breast milk. With regard to cigarette smoking as a source of exposure to Cd and Pb, there were effects of smoking on Cd concentration in blood and correlations between the smoking index and Cd concentrations in maternal blood (ρ=0.593; P<0.001) and mature milk (ρ=0.271; P=0.011) and Pb concentration in transitional milk (ρ=0.280; P=0.042). Regarding fish, we found correlations between weekly consumption frequency and total Hg concentrations in maternal blood (ρ=0.292; P=0.003) and mature milk (ρ=0.303; P=0.003). The number of dental amalgam fillings correlated with total Hg concentrations in colostrum (ρ=0.489; P=0.005) and transitional milk (ρ=0.309; P=0.018). As for the essential element status, only Se levels in maternal serum decreased by 10% in persons who continued smoking during pregnancy compared to non-smokers. In conclusion, the levels of main toxic metals Cd, Pb and Hg and essential elements Ca, Fe, Cu, Zn and Se in maternal blood and three types of breast milk samples in the studied area of coastal Croatia showed no risk of disrupted essential element levels with regard of toxic metal exposure in both breastfeeding women and their infants.

ABC- and SLC-Transporters in Murine and Bovine Mammary Epithelium--Effects of Prochloraz

Some chemicals are ligands to efflux transporters which may result in high concentrations in milk. Limited knowledge is available on the influence of maternal exposure to chemicals on the expression and function of transporters in the lactating mammary gland. We determined gene expression of ABC and SLC transporters in murine mammary tissue of different gestation and lactation stages, in murine mammary cells (HC11) featuring resting and secreting phenotypes and in bovine mammary tissue and cells (BME-UV). Effects on transporter expression and function of the imidazole fungicide prochloraz, previously reported to influence BCRP in mammary cells, was investigated on transporter expression and function in the two cell lines. Transporters studied were BCRP, MDR1, MRP1, OATP1A5/OATP1A2, OCTN1 and OCT1. Gene expressions of BCRP and OCT1 in murine mammary glands were increased during gestation and lactation, whereas MDR1, MRP1, OATP1A5 and OCTN1 were decreased, compared to expressions in virgins. All transporters measured in mammary glands of mice were detected in bovine mammary tissue and in HC11 cells, while only MDR1 and MRP1 were detected in BME-UV cells. Prochloraz treatment induced MDR1 gene and protein expression in both differentiated HC11 and BME-UV cells and increased protein function in HC11 cells, resulting in decreased accumulation of the MDR1 substrate digoxin. In conclusion, our results demonstrate that murine (HC11) and bovine (BME-UV) mammary epithelial cells can be applied to characterize expression and function of transporters as well as effects of contaminants on the mammary transporters. An altered expression, induced by a drug or toxic chemical, on any of the transporters expressed in the mammary epithelial cells during lactation may modulate the well-balanced composition of nutrients and/or secretion of contaminants in milk with potential adverse effects on breast-fed infants and dairy consumers.

Maternal blood, plasma, and breast milk lead: lactational transfer and contribution to infant exposure

BACKGROUND

Human milk is a potential source of lead exposure. Yet lactational transfer of lead from maternal blood into breast milk and its contribution to infant lead burden remains poorly understood.

OBJECTIVES

We explored the dose-response relationships between maternal blood, plasma, and breast milk to better understand lactational transfer of lead from blood and plasma into milk and, ultimately, to the breastfeeding infant.

METHODS

We measured lead in 81 maternal blood, plasma, and breast milk samples at 1 month postpartum and in 60 infant blood samples at 3 months of age. Milk-to-plasma (M/P) lead ratios were calculated. Multivariate linear, piecewise, and generalized additive models were used to examine dose-response relationships between blood, plasma, and milk lead levels.

RESULTS

Maternal lead levels (mean±SD) were as follows: blood: 7.7±4.0 μg/dL; plasma: 0.1±0.1 μg/L; milk: 0.8±0.7 μg/L. The average M/P lead ratio was 7.7 (range, 0.6-39.8) with 97% of the ratios being >1. The dose-response relationship between plasma lead and M/P ratio was nonlinear (empirical distribution function=6.5, p=0.0006) with the M/P ratio decreasing by 16.6 and 0.6 per 0.1 μg/L of plasma lead, respectively, below and above 0.1 μg/L plasma lead. Infant blood lead level (3.4±2.2 μg/dL) increased by 1.8 μg/dL per 1 μg/L milk lead (p<0.0001, R2=0.3).

CONCLUSIONS

The M/P ratio for lead in humans is substantially higher than previously reported, and transfer of lead from plasma to milk may be higher at lower levels of plasma lead. Breast milk is an important determinant of lead burden among breastfeeding infants.

Heavy metals in raw cow and ewe milk from north-east Iran

The presence of toxic metals in milk may create significant health problems for the population. In this study, 1440 raw cow and ewe milk samples from 18 townships in north-east Iran were analysed in four different seasons. Lead, cadmium and mercury levels were determined using atomic absorption spectrophotometry. Mean concentration of lead, cadmium and mercury in cow milk samples was 12.9 ± 6.0, 0.3 ± 0.3 and 3.1 ± 0.3 ng g⁻¹, respectively, and in ewe milk samples, these mean values were 14.9 ± 7.8, 1.6 ± 1.2 and 3.1 ± 0.3 ng g⁻¹, respectively. Statistical analyses showed that lead and cadmium concentrations in ewe milk were significantly higher than in cow milk. Concentrations of these metals in ewe milk varied significantly with different seasons. As the concentrations did not exceed the safety limits, they could not pose a serious danger to public health.

Mercury concentrations in hair from neonatal and juvenile Steller Sea Lions (Eumetopias jubatus): implications based on age and region in this northern Pacific marine sentinel piscivore

Mercury is a global contaminant of concern for the fetus and the neonate of piscivores. Methylmercury, produced within marine ecosystems, is of particular concern as a readily absorbed neurotoxicant transported across the blood brain barrier and transplacentally. In the North Pacific Ocean, Steller sea lions are broadly distributed apex predators and, as such, integrate complex food webs and the associated exposure and possible adverse effects of toxic and infectious agents. Hair, including lanugo, was examined using regional and age groupings to assess mercury concentrations in young Alaskan Steller sea lions. The highest concentrations of mercury occurred in the youngest animals, likely via in utero exposure. Based on the adverse developmental outcomes of methylmercury toxicity this specific cohort is of concern. Regionally, higher concentrations of mercury were observed in the endangered western population of Steller sea lions and mirrored patterns observed in human biomonitoring studies of Alaskan coastal communities. These data have broader implications with respect to human and ecosystem health as Steller sea lions rely on similar prey species and foraging areas as those targeted by commercial fisheries and subsistence users and are therefore valuable sentinels of marine ecosystem health.

Mercury concentration in the breast milk of Iranian women

Human milk is usually the only source of food for infants during the first 4 to 5 months of their life. In this research, 80 human milk samples were collected from mothers in Tehran, Noushahr and the countryside of Tabriz, Iran, who were not occupationally exposed to mercury. The mean concentration of mercury in breast milk obtained from mothers in the countryside of Tabriz, Noushahr and Tehran was 0.86, 0.15 and 0.12 μg/L, respectively. There was a significant difference in mercury concentration in human breast milk between that from the countryside of Tabriz with that from Tehran and Noushahr. Only 3.7% of infant samples (three infants) had mercury concentration higher than normal versus the WHO recommended limit (0.5 μg g(-1)). The fish consumption of these mothers in Tehran and Noushahr was a factor that significantly affected the mercury concentration in their breast milk. Also, their age affected the mercury levels in breast milk (p = 0.04).

In which regions is breast-feeding safer from the impact of toxic elements from the environment?

Owing to its unique nutritional and immunological characteristics, breast milk is the most important food source for infants. But, children are at greater risk for exposure to environmental toxicants from breast milk. The aim of this study was to evaluate the influence of environmental pollution on essential and toxic element contents of breast milk and determine the risky locations in our population. This study was conducted on women who were breastfeeding (n=90). Milk samples were collected at three locations in Marmara region, Turkey: highly industrialized region highly affected by pollution, urbanized region moderately and rural area that is affected little. Breast milk samples (5 mL) were collected at approximately one month postpartum (mature milk). The concentrations of cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn) in milk samples were compared to the milk samples coming from different locations.Lead, cadmium, nickel, chromium, iron and manganese levels in the breast milk are highest and engrossing especially in rural areas compared to the other regions but cobalt, copper, zinc levels are highest in highly industrial areas. The levels of essential and toxic elements in breast milk can vary in different regions. The levels presented in our study are above some countries' data albeit not at toxic levels. Because of global effects, environmental pollution is not the problem for industrializing regions only. Rural area also may not be safe for breastfeed babies.

Long-term human exposure to lead from different media and intake pathways

Lead (Pb) is well known as an environmental pollutant: it can accumulate in various media, so actual lead exposure reflects both historical and present contaminations. Two main challenges then emerge: obtaining updated information to gain an overall picture of the sources of exposure, and predicting the resulting internal body exposure levels and effects that occur under long-term exposure conditions. In this paper, a modeling approach is used to meet these challenges with reference to Danish exposure conditions. Levels of lead content in various media have been coupled with data for lead intake and absorption in the human body, for both children and adults. An age-dependent biokinetic model allows then for determination of the blood lead levels resulting from chronic exposure. The study shows that the actual intake of lead is up to 27% of the Provisional Tolerable Daily Intake (PTDI) for children and around 8% for adults. It is confirmed that the critical route of exposure is via ingestion, accounting for 99% of total lead intake, while inhalation contributes only to 1% of total lead intake. The resulting lead levels in the blood after 2 years of exposure to actual contamination conditions have been estimated as up to 2.2μg/dl in children and almost 1μg/dl in adults. Impacts from lead can occur even at such levels. The role of historical and present sources to lead in the environment is discussed, and, for specific child and adult exposure scenarios, external-internal concentration relationships for the direct linkage between lead in environmental media and resulting concentrations of lead in blood are then presented.

Chemical Biomarkers of Human Breast Milk Pollution

Human milk is, without question, the best source of nutrition for infants containing the optimal balance of fats, carbohydrates and proteins for developing babies. Breastfeeding provides a range of benefits for growth, immunity and development building a powerful bond between mother and her child. Recognition of the manifold benefits of breast milk has led to the adoption of breast-feeding policies by numerous health and professional organizations such as the World Health Organization and American Academy of Pediatrics.In industrially developed as well as in developing nations, human milk contamination by toxic chemicals such as heavy metals, dioxins and organohalogen compounds, however, is widespread and is the consequence of decades of inadequately controlled pollution. Through breastfeeding, the mother may transfer to the suckling infant potentially toxic chemicals to which the mother has previously been exposed.In the present review, environmental exposure, acquisition and current levels of old and emerging classes of breast milk pollutants are systematically presented. Although scientific evidences indicated that the advantages of breast-feeding outweigh any risks from contaminants, it is important to identify contaminant trends, to locate disproportionately exposed populations, and to take public health measures to improve chemical BM pollution as possible.

Mercury and lead during breast-feeding

Hg and Pb are of public health concern due to their toxic effects on vulnerable fetuses, persistence in pregnant and breast-feeding mothers, and widespread occurrence in the environment. To diminish maternal and infant exposure to Hg and Pb, it is necessary to establish guidelines based on an understanding of the environmental occurrence of these metals and the manner in which they reach the developing human organism. In the present review, environmental exposure, acquisition and storage of these metals via maternal–infant interaction are systematically presented. Though Hg and Pb are dispersed throughout the environment, the risk of exposure to infants is primarily influenced by maternal dietary habits, metal speciation and interaction with nutritional status. Hg and Pb possess similar adverse effects on the central nervous system, but they have environmental and metabolic differences that modulate their toxicity and neurobehavioural outcome in infant exposure during fetal development. Hg is mainly found in protein matrices of animal flesh (especially fish and shellfish), whereas Pb is mainly found in osseous structures. The potential of maternal acquisition is higher and lasts longer for Pb than for Hg. Pb stored in bone has a longer half-life than monomethyl-mercury acquired from fish. Both metals appear in breast milk as a fraction of the levels found in maternal blood supplied to the fetus during gestation. Habitual diets consumed by lactating mothers pose no health hazard to breast-fed infants. Instead, cows' milk-based formulas pose a greater risk of infant exposure to neurotoxic substances.

Analysis of the health risk of exposure to breast milk mercury in infants in Taiwan

The aim of this study was to assess the total concentration and health risk to infants of breast milk mercury in urban mothers and mothers married to fishermen in relation to fish intake in Taiwan. A total of sixty-eight healthy mothers were recruited for the study. The breast milk mercury geometric mean concentration was 2.02 microgl(-1) (n=56, range: 0.24-9.45 microgl(-1)) for the city group and 2.04 microgl(-1) (n=12, range: 0.26-8.62 microgl(-1)) for the fishermen's group. Of the three sources of mercury exposure (i.e., ingestion (breast milk), inhalation (ambient air), and dermal exposure (shower)), breast-feeding was found to be the largest (96.3-99.6% of the total). From a Monte Carlo simulation, in which methyl mercury accounted for about 50% of total mercury, the hazard quotient (exposure estimate/oral minimal risk level or target organ toxicity dose) exceeded 1.0 for 12.9% of urban babies and 18.8% of fishermen's babies (chronic oral minimal risk level and target organ toxicity dose: 3 x 10(-4)mgkg(-1)d(-1)). The calculated mercury exposure was 3.02 x 10(-1) microgkg(-1)d(-1) for a 3.49 kg urban baby boy and 3.06 x 10(-1) microgkg(-1)d(-1) for a 3.44 kg urban baby girl. These results suggest the life style of mothers (eating raw fish and shellfish such as used in "Sashimi" and "Sushi," and vitamin supplementation) may influence the mercury concentration in breast milk.

Gestational mercury vapor exposure and diet contribute to mercury accumulation in neonatal rats

Exposure of pregnant Long-Evans rats to elemental mercury (Hg0) vapor resulted in a significant accumulation of Hg in tissues of neonates. Because elevated Hg in neonatal tissues may adversely affect growth and development, we were interested in how rapidly Hg was eliminated from neonatal tissues. Pregnant rats were exposed to 1, 2, or 4 mg Hg0 vapor/m3 or air (controls) for 2 hr/day from gestation day 6 (GD6) through GD15. Neonatal brain, liver, and kidney were analyzed for total Hg at various times between birth and postnatal day 90 (PND90). Milk was analyzed for Hg between birth and weaning (PND21). Before weaning, the Hg levels in neonatal tissues were proportional to maternal exposure concentrations and were highest in kidney followed by liver and then brain. There was no elimination of Hg between birth and weaning, indicating that neonates were exposed continuously to elevated levels of Hg during postpartum growth and development. Consumption of milk from exposed dams resulted in a slight increase in kidney Hg concentration during this period. Unexpectedly, neonatal Hg accumulation increased rapidly after weaning. Increased Hg was measured in both control and exposed neonates and was attributed to consumption of NIH-07 diet containing trace levels of Hg. By PND90, tissue Hg levels equilibrated at concentrations similar to those in unexposed adult Long-Evans rats fed the same diet. These data indicate that dietary exposure to trace amounts of Hg can result in a significantly greater accumulation of Hg in neonates than gestational exposure to high concentrations of Hg0 vapor.

Toxic metals status in human blood and breast milk samples in an integrated steel plant environment in Central India

Owing to its unique nutritional and immunological characteristics, human milk is the most important food source for infants. Breast milk can, however, also be a pathway of maternal excretion of toxic elements. Selected toxic elements (As, Pb, Mn,a Hg and Cd) were determined in human breast milk and blood samples obtained from 120 subjects related to an integrated steel plant environment located in central India. Samples of breast milk and blood from subjects living outside the steel plant environment were also analyzed for comparative study. Higher levels of these toxic elements were found in blood samples as compared to breast milk samples. Plant workers showed the higher presence of these metals in their breast milk and blood samples compared to the residents of the area and the subjects living outside the industrial environment, respectively. Mn, Pb and Hg have shown a higher tendency to associate with blood and breast milk than As and Cd. The order of occurrence of these metals in blood and milk samples thus found is Mn > Pb > Hg > As > Cd.

Subchronic mercury treatment of rats in different phases of ontogenesis: functional effects on the central and peripheral nervous system

Electrophysiological changes caused by inorganic mercury administration during the pre- and/or postnatal development were studied. Pregnant female Wistar rats were treated, by gavage, with 0.4, 0.8 or 1.6 mg/kg mercury (HgCl2 diluted in distilled water): 1/ from day 5 to 15 during pregnancy (P protocol); 2/ from day 5 to 15 of pregnancy+for 4 weeks of lactation (P+L protocol); 3/ from day 5 to 15 of pregnancy+for 4 weeks of lactation, and the offspring were further treated for 8 weeks post-weaning (P+L+P protocol). Electrophysiological parameters (electrocorticogram, cortical evoked potentials, conduction velocity and refractory periods of peripheral nerve) of the male offspring from dams in the groups treated according to the above protocols were investigated at the age of 12 weeks. The rats' spontaneous and evoked electrophysiological activity underwent dose- and treatment-dependent changes following the treatment (increased frequency of spontaneous activity, lengthened latencies and duration of evoked potentials, lower conduction velocity of the peripheral nerve, etc.). In the same rats, however, the treatment failed to cause major signs of general intoxication. The results emphasize the functional neurotoxic risk arising from the continuous presence of inorganic mercury in the human environment, and point to possible use of early functional changes for monitoring the effects of mercury.

Effect of breast milk lead on infant blood lead levels at 1 month of age

Nursing infants may be exposed to lead from breast milk, but relatively few data exist with which to evaluate and quantify this relationship. This route of exposure constitutes a potential infant hazard from mothers with current ongoing exposure to lead as well as from mothers who have been exposed previously due to the redistribution of cumulative maternal bone lead stores. We studied the relationship between maternal breast milk lead and infant blood lead levels among 255 mother-infant pairs exclusively or partially breast-feeding through 1 month of age in Mexico City. A rigorous, well-validated technique was used to collect, prepare, and analyze the samples of breast milk to minimize the potential for environmental contamination and maximize the percent recovery of lead. Umbilical cord and maternal blood lead were measured at delivery; 1 month after delivery (+/- 5 days) maternal blood, bone, and breast milk and infant blood lead levels were obtained. Levels of lead at 1 month postpartum were, for breast milk, 0.3-8.0 microg/L (mean +/- SD, 1.5 +/- 1.2); maternal blood lead, 2.9-29.9 microg/dL (mean +/- SD, 9.4 +/- 4.5); and infant blood lead, 1.0-23.1 microg/dL (mean +/- SD, 5.5 +/- 3.0). Infant blood lead at 1 month postpartum was significantly correlated with umbilical cord (Spearman correlation coefficient rS = 0.40, p < 0.0001) and maternal (rS= 0.42, p < 0.0001) blood lead at delivery and with maternal blood (rS= 0.67, p < 0.0001), patella rS = 0.19, p = 0.004), and breast milk (rS = 0.32, p < 0.0001) lead at 1 month postpartum. Adjusting for cord blood lead, infant weight change, and reported breast-feeding status, a difference of approximately 2 microg/L (ppb; from the midpoint of the lowest quartile to the midpoint of the highest quartile) breast milk lead was associated with a 0.82 microg/dL increase in blood lead for breast-feeding infants at 1 month of age. Breast milk lead accounted for 12% of the variance of infant blood lead levels, whereas maternal blood lead accounted for 30%. Although these levels of lead in breast milk were low, they clearly have a strong influence on infant blood lead levels over and above the influence of maternal blood lead. Additional information on the lead content of dietary alternatives and interactions with other nutritional factors should be considered. However, because human milk is the best and most complete nutritional source for young infants, breast-feeding should be encouraged because the absolute values of the effects are small within this range of lead concentrations.

Tagum study II: follow-up study at two years of age after prenatal exposure to mercury

OBJECTIVES

To correlate the presence and levels of total mercury (THg) in cord blood and meconium indicating prenatal exposure with developmental milestones at 2 years and to compare these subjects with controls of comparable age using cognitive adaptive test and clinical linguistic auditory milestone scale (CAT/CLAMS).

METHODS

In 48 of the original Tagum (T) subjects, cord blood and meconium Hg levels, head circumference (HC) at birth, and duration of breastfeeding were correlated with CAT/CLAMS at 2 years. At 2 years, THg levels using cold atomic vapor absorption spectrometry were determined in the hair of 46 T subjects and 88 Saranggani (S) controls; THg levels in blood were tested in 48 T subjects and 45 S controls. These levels were correlated with CAT/CLAMS. Both groups had standard physical and neurologic examinations, hearing screen using transitory evoked otoacoustic emissions, serum glutamate pyruvate transaminase, and routine urinalysis. A prevalidated Socioeconomic Means Test was given to both groups.

RESULTS

The Hg level in cord blood was negatively correlated with CAT/CLAMS at 2 years. The HC at birth was negatively correlated with levels of Hg in hair of T subjects 2 years later. HC at birth and 2 years hence were positively correlated with CAT/CLAMS. The following were significantly higher in S controls than in T subjects: expressive language quotient 82.569 +/- 2.21 versus 71.57 +/- 2.61; CLAMS 87.96 +/- 2.43 versus 77.67 +/- 2.51; CAT 90.57 +/- 2.22 versus 83.15 +/- 1.43; and full-scale developmental quotient 89.31 +/- 2.14 versus 80.56 +/- 1.86. Fifteen percent of T subjects had global delay (full-scale developmental quotient <or=70) versus 5.48% in S controls. Hg levels in hair and blood in both T subjects and S controls at 2 years showed no correlation with CAT/CLAMS. The duration of breastfeeding in both groups likewise showed no correlations with CAT/CLAMS.

CONCLUSION

The study suggests that prenatal Hg exposure is correlated with lower scores in neurodevelopmental screening, but more so in the linguistic pathway. Other confounding factors cannot be eliminated.

Selenium status of low-selenium area residents: Polish experience

The concentration of selenium (Se) in human organism varies widely between geographical areas depending on its content in soil and plants, dietary Se intake, bioavailability and retention, mineral interactions and other factors. The study includes healthy inhabitants of different regions of Poland; pregnant women, lactating women, children from 0 to 15 years of age and adults. Systematic determinations allow us to observe changes of the concentration of Se in time, which may be significant for developing preventive action. The results obtained confirm our thesis that Se concentration in the blood of the inhabitants of Poland depends on the region of the country. In recent years, in a considerable number of Polish inhabitants, the concentration of Se in blood plasma has been relatively low-about 50-55 microg/l, and the calculated daily dietary intake about 30-40 microg/day. The low levels of the element in the blood and urine are probably due to its deficiency in the diet.

Declining risk of methylmercury exposure to infants during lactation

Methylmercury (MeHg) can be transferred to infants through milk, in addition to passage through the placenta during intrauterine life. The higher MeHg accumulation and susceptibility to toxicity in the fetus than in the mother during the gestation period is well known. However, the contribution of Hg exposure through breast milk to the MeHg concentration in infants is not clear. Our objective in this study was to examine the changes in MeHg levels in infants who were reared on breast milk to evaluate the risks between fetal and breast-feeding periods based on Hg concentrations in red blood cells (RBCs-Hg). RBCs-Hg and plasma-Hg concentrations (Plasma-Hg) in seven pairs of maternal and infant blood samples were compared at birth and 3 months after parturition. RBCs to Plasma-Hg ratio was approximately 8:1 for mothers at parturition and after 3 months, suggesting that their Hg source is MeHg from consumed fish as is general in Japanese. In all seven cases, RBCs-Hg in the umbilical cords were higher than those in the mothers at parturition. The geometric mean of RBCs-Hg in umbilical cords (10.6ng/g) was about 1.4 times higher than that in the mothers (7.1ng/g). There was a strong correlation in RBCs-Hg in mothers and umbilical cords. However, all the infants showed declines in Hg concentrations throughout the breast-feeding period. The geometric mean RBCs-Hg at 3 months of age was 5.8ng/g, accounting for 54% of that in the umbilical cords. Consequently, maternal RBCs-Hg surpassed that of infants at 3 months, opposite to the situation at parturition. The decline in infant RBCs-Hg during the breast-feeding period can be explained by the low Hg transfer through breast milk and the rapid growth of infants after birth. The geometric mean Milk-Hg was low (0.21ng/g), around 20% of that in maternal Plasma-Hg. The average body weight of infants at 3 months increased to about 1.9 times of that at birth. Thus, offspring are subjected to MeHg exposure through both the gestation and the breast-feeding periods; the risk is especially high during gestation but may decrease during breast-feeding.

Evaluation of changes in methylmercury accumulation in the developing rat brain and its effects: a study with consecutive and moderate dose exposure throughout gestation and lactation periods

Methylmercury (MeHg) can be transferred to the fetus through the placenta and to newborn offspring through breast milk. The higher mercury (Hg) accumulation and susceptibility to toxicity in the fetus than in the mother during the gestation period is well known. However, the contribution of MeHg exposure through breast milk to the brain Hg concentration in offspring is not clear. The purposes of this study were to evaluate the changes in Hg concentration in the brain of offspring and its effects on the developing rat brain, based on consecutive and moderate doses of MeHg throughout gestation and lactation. Adult female rats were given a diet containing 5 ppm Hg (as MeHg) for 8 weeks. The administration level was thought not to cause adverse effects in adult rats. The rats were then mated and subsequently given the same diet throughout gestation and after parturition. The newborn offspring were placed with the mothers until postnatal day 30. The offspring were exposed to MeHg throughout their intrauterine life through the placenta, and during the postnatal developing phase via contaminated milk. Furthermore, they were given the same diet containing MeHg for 2 months following weaning. On the day of parturition, the concentration of Hg in the brains of newborns was 1.4 times higher than that in the mothers. During the suckling period the concentration in the brain of the offspring rapidly declined to 1/5 of that at birth, suggesting that MeHg transport by milk was limited while the brain and body volumes increased rapidly. The concentration increased gradually again after the offspring started the contaminated diet. In behavioral tests performed at 5 and 6 weeks of age, MeHg-exposed rats showed a significant deficit in motor coordination in the rotarod test and a learning disability in the passive avoidance response test, compared with controls. Histopathologically, focal cerebellar dysplasia, including the heterotopic location of Purkinje cells and granule cells, was observed. These abnormalities may be induced by the effect of highly accumulated MeHg in the brain during the gestation period. Thus, although offspring are subjected to consecutive and moderate dose MeHg exposure throughout both the gestation and suckling periods, the risk is especially high during gestation but may decrease during lactation.

Distribution of methylmercury and inorganic mercury in neonate hamsters dosed with methylmercury during fetal life

The study of the effects of methylmercury (MeHg) contamination has intensified since the MeHg outbreaks in Japan and Iraq. However, most of these studies used high doses of MeHg to obtain its most severe effects. This work identified the MeHg targets in neonate hamsters after administration of two different single oral doses of radiolabeled methylmercury chloride (Me203HgCl) to two groups of pregnant hamsters. The low-dose group received 0.05 microg of 203Hg as Me203HgCl per gram of body weight and the radioactivity was 6.6x10(3) Bq. The high-dose group received 0.55 microg of 203Hg as Me203HgCl per gram of body weight with 2x104 Bq. In the first day of life, the brain was the organ with the highest Me203Hg concentration, followed by the liver, kidneys, and intestines. However, these values of Me203Hg decreased at different rates in all organs until 12 days of life, whereas total 203Hg in the body did not change during the same period. This suggests an age-dependent Me203Hg body distribution instead of an elimination of Me203Hg from the body.

Lead accumulation in human ovarian follicular fluid, and in vitro effect of lead on progesterone production by cultured human ovarian granulosa cells

Lead content of ovarian follicular fluid obtained from 23 women was determined by atomic absorption spectrophotometry. In an in vitro experiment the direct effect of lead on the morphology and on progesterone (P) production by cultured granulosa cells of six women was investigated. Follicular fluid and granulosa cells were obtained from follicular aspirates of women undergoing in vitro fertilization (IVF) and embryo transfer (ET). Granulosa cells were cultured for 48 h to form monolayers in the presence or absence of lead acetate (100-1,600 microM). The effect of the metal proved to be concentration dependent. While 100-400 microM lead had no effect on the integrity of the monolayer, concentrations as high as 800 microM or higher inhibited cell adhesion and induced detachment of cells. The lead levels found in follicular fluid were 11.29 +/- 1.38 microg/L (0.056 +/- 0.007 microM). With lead in vitro at 1,600 microM (331.5 mg/L) there resulted a significant decrease in P production by granulosa cells. This concentration is very much higher than that measured in follicular fluid of IVF/ET patients, specifically nonexposed to lead, and even higher than mean blood levels reported by others in high exposure groups. In conclusion, lead seems not to exert a specific effect on the steroidogenesis by cultured human granulosa cells. Therefore, the lead levels measured in the ovarian follicular fluid seem not to pose a hazard with respect to progesterone secretion by the ovary.

The Tagum study I: analysis and clinical correlates of mercury in maternal and cord blood, breast milk, meconium, and infants' hair

OBJECTIVES

To compare the indicators and levels of mercury (Hg) exposure in the mother with those in the fetal compartments, and determine its effects on the newborn.

METHODS

Hg levels using atomic absorption spectrophotometry were determined in maternal blood, breast milk, cord blood, infants' hair, and meconium of 78 consecutive mother-infant pairs in a community with high Hg pollution. The prevalence and levels of Hg both in meconium and in cord blood were correlated with maternal and infant risk factors.

RESULTS

The prevalence of Hg in the fetal compartments was higher than in the maternal fluid compartments. Hg was present in 6.4% of maternal blood and 6.4% of breast milk, as compared with 16.7% of cord blood, 31.6% of infants' hair, and 46.1% of meconium. Forty-six percent of infants with Hg in cord blood had none in meconium, whereas 80.6% with Hg in meconium had none in cord blood. Hg was not present in the maternal blood of all infants (n = 36) with Hg in their meconium. Among those with detectable Hg, the mean levels were: mothers' blood 24 parts per billion +/- 5.47, cord blood 53.3 parts per billion +/- 37.49, and meconium 48.6 +/- 43.48. Quantitative measurement in hair was not done because of insufficient sample. Paired comparisons were all significant between Hg levels in the mothers' blood and meconium, mothers' blood and cord blood, and cord blood and meconium. Regression analysis showed Hg levels in meconium to be correlated with prevalence of Hg in infants' hair, length of stay in Tagum, and meconium-stained amniotic fluid. Fisher's Exact probability test showed that the prevalence of Hg in meconium was significantly related to the prevalence of Hg in the mothers' blood and length of stay in Tagum. The prevalence of Hg in cord blood was significantly related to the prevalence in the mothers' blood. Regression analysis of levels of Hg in cord blood showed a significant relation to levels in mothers' blood (.0001), prevalence in infants' hair (.0126), gestational age (GA) (.0091), and head circumference (HC) (.0469). By quadrant analysis of weight against HC in 66 full-term infants all of 4 infants weighing an average of >3000 g at birth and with HCs lower than the fifth percentile had Hg in meconium.

CONCLUSION

The higher prevalence and levels of Hg in the fetal compartments reflect the ease of placental transfer with fetal trapping. Hg determinations in the mothers' blood underestimate the degree and extent of fetal exposure. There is a significant difference in each compartment's ability to reflect Hg exposure of the fetus. A small HC may be associated with the presence of Hg in meconium. Hg in meconium should be measured in addition to cord blood to determine the load of fetal Hg.

Reproductive toxicity of occupational mercury. A review of the literature

OBJECTIVES

This paper aims to give the dental practitioner insight into the potential reproductive effects of handling dental silver amalgam, c.q. mercury.

DATA SOURCES

Experimental studies on animals, case reports and epidemiologic studies.

STUDY SELECTION

Experimental animal studies show high doses/concentrations of mercury to increase the risk of reproductive disorders, e.g. infertility, spontaneous abortion, stillbirth and congenital malformations. Some case reports suggest an association between the disorders in humans and high levels of mercury. Therefore, the present article reviews epidemiological studies on the relationship between occupational exposure to mercury, mainly as vapour in the dental practice, and females' procreative ability. Studies concerning the reproductive effects of males' occupational mercury body burden are scarce. The reproductive risk of patients' mercury uptake from silver amalgam fillings is assessed.

CONCLUSIONS

It seems warranted to conclude that negative reproductive effects from exposure to mercury in the dental office are unproven, but safe levels have not been established. Seemingly problems are unlikely to occur, unless a poor hygiene causes the mercury concentration in the air to exceed females' time-weighted long-term Threshold Limit Value (TLV). Consequently, in view of the in general low amounts of mercury stemming from dental amalgam fillings, the population at large is at even less risk than dental staff. The effects of occupational elemental mercury concentrations lower than the TLV on the menstrual cycle, conception, male fertility and children's behaviour need, however, more research.

Determination of lead and other metals in a residential area of greater Calcutta

The aim of the study was to determine the major source and extent of metal pollution in a residential area of Greater Calcutta. In this area approximately 50,000 people reside in the vicinity of a lead factory that produces lead ingots and lead alloys. Many people, especially children, are affected by lead toxicity. Soils, waters, road dust, leaf dust, leaves and pond sediments were sampled in and around the factory area. Aliquots of the samples were mineralized with nitric acid and hydrogen peroxide in a microwave system. Lead and 19 other elements were quantified in the digests by inductively coupled plasma mass spectrometry. The performance of the procedure was confirmed by analyzing NBS-BCR standard reference soil, leaves, sediment samples. The soils are highly contaminated not only with lead (4.7%), but also with Cd (0.08%), Ag (0.001%), Cu (0.02%), Zn (1.0%), As (1.0%), Mo (0.003%), Sn (0.003%) and Hg (0.03%) (metal concentrations given in parentheses are maximum). Moving away from the smelter, most of metal concentrations, especially Pb, As, Mo, Cu, Hg, Zn, Cd, Sn and Ag, decreased exponentially over increasing distance. In the residential areas near the smelter, notably to the west side of the factory, metal concentrations significantly breached the threshold trigger values set in India by the Central Pollution Control Board (CPCB). Particulate materials from the smelter stack appear to contaminate soils up to at least 0.5 km. However, abnormally high metal levels in the immediate smelter area may be due to primarily fugitive emissions. The surface waters are only contaminated by arsenic ranges from 0.05 to 13.5 mg/l, but the ground water is currently not polluted by lead and arsenic. An appropriate treatment plant with some intervention measures should be taken to save the locality.

Mercury content in skin-lightening creams and potential hazards to the health of Saudi Women

It seems evident from a wealth of scientific research that mercury is toxic. Because of the nature of the Saudi markets, different brands of skin-lightening creams are widely available. In this study, 38 skin-lightening cream samples were collected and analyzed for mercury by inductively coupled plasma spectrometry after an acid digestion procedure. About 45% of the tested skin-lightening cream samples contained mercury at levels well above the FDA's acceptable limit of 1 ppm. These findings are alarming and have wide legal and educational implications for Saudi Arabia in particular and developing countries in general. Further investigation for possible adverse health effects is also needed.