Concentrations of lead in blood, hair and saliva of German children living in three different areas of traffic density

A critical review of biomarkers used for monitoring human exposure to lead: advantages, limitations and future needs

Lead concentration in whole blood (Blood-Pb) is the primary biomarker used to monitor exposure to this metallic element. However, the difficulty in assessing the exact nature of Pb exposure is dependent not so much on problems with current analytical methodologies, but rather on the complex toxicokinetics of Pb within various body compartments. If we are to differentiate more effectively between Pb that is stored in the body for years and Pb from recent exposure, information on other biomarkers of exposure may be needed. None of the current biomarkers of internal Pb dose has yet been accepted by the scientific community as a reliable substitute for a Blood-Pb measurement. This review focuses on the limitations of biomarkers of Pb exposure, and the need to improve the accuracy of their measurement. We present here only the traditional analytical protocols in current use and we attempt to assess the influence of confounding variables on Blood-Pb levels. Finally, we discuss the interpretation of Blood-Pb data with respect to both external and endogenous Pb exposure, past or recent exposure, as well as the significance of lead determinations in human specimens including hair, nails, saliva, bone, blood, urine, feces, and exfoliated teeth.

Comparative metal distribution in hair of Pakistani and Libyan population and source identification by multivariate analysis

Using nitric acid-perchloric acid wet digestion based FAAS method ten selected metals (Cd, Co, Cr, Fe, K, Mn, Na, Ni, Pb and Zn) were determined in the scalp hair of male Pakistani and Libyan donors (n = 62), between 3-54 years age and residing in typical urban areas. The study was taken up to identify sources of metal distribution in two diverse population segments exposed to different environments. Sodium emerged with the highest mean hair concentration of 511.0 microg/g and 496.9 mug/g for Libyan and Pakistani donors respectively, followed by K, at 266.2 microg/g and 242.4 microg/g for the two donor categories. Cadmium showed the lowest mean hair concentration for both Pakistani (0.380 microg/g) and Libyan (0.530 microg/g) donors. Levels of Na, K, Pb, Cr and Cd were higher in hair of Libyan donors compared with Pakistani counterparts which showed higher comparative levels of Zn, Fe, Co, Ni and Mn. Strong metal-to-metal correlations were found between Na-K (r = 0.638) and Cd-Co (r = 0.574) for Pakistani donors, while for Libyan donors, Na-K (r = 0.680) and Fe-Mn (r = 0.624) correlations emerged as strongly significant. Only K was found to have a strong positive correlation (r = 0.611) with age for Pakistani donors while this correlation was significantly negative (r = -0.500) for Libyan donors, probably arising from individual food habits. Other metals showed no viable relationship with age. Principal Component Analysis (PCA) and Cluster Analysis (CA) of the data evidenced food, industrial emissions and automobile emissions as possible sources of metal distribution. The results of the present study are compared with those reported for subjects from other regions of the world.

Lead levels in blood and saliva in a low-income population of Detroit, Michigan

The relationships between blood lead (PbB) and saliva lead (PbSa) concentrations and the determinants of PbB and PbSa status in 970 low-income adults in the city of Detroit, Michigan were explored. Average PbB and PbSa values in the sample population were found to be 2.7+/-0.1 microg/dl and 2.4+/-0.13 microg/l (equivalent to 0.24+/-0.13 microg/dl), respectively, and a weak but statistically significant association was found between the lead levels in the two types of body fluid samples. The average PbB level for men (4.0+/-0.56 microg/dl) was higher than that for women (2.7+/-0.11 microg/dl); other significant predictors of PbB included age, level of education, being employed, income level, the presence of peeling paint on the wall at home and smoking. There was no gender- or age-dependent difference in blood saliva values but statistically significant correlations were found between PbSa and level of education, employment, income level and smoking. Dental caries was severe in this population. Only 0.5% of the participants had no clinical signs of caries, over 80% had cavitated carious lesions (i.e., lesions that had progressed into dentin), and the number of lost teeth and carious lesions averaged 3.4 and 30, respectively. Weak but significant associations were found between PbB as well as PbSa and measures of dental caries in the study population. The positive associations are believed to be a reflection of the fact that the risk factors for dental caries, especially in low-income populations of the US, overlap extensively with those of lead poisoning and may not have a causal significance.

A critical review of biomarkers used for monitoring human exposure to lead: advantages, limitations, and future needs

Lead concentration in whole blood (BPb) is the primary biomarker used to monitor exposure to this metallic element. The U.S. Centers for Disease Control and Prevention and the World Health Organization define a BPb of 10 microg/dL (0.48 micromol/L) as the threshold of concern in young children. However, recent studies have reported the possibility of adverse health effects, including intellectual impairment in young children, at BPb levels < 10 microg/dL, suggesting that there is no safe level of exposure. It appears impossible to differentiate between low-level chronic Pb exposure and a high-level short Pb exposure based on a single BPb measurement; therefore, serial BPb measurements offer a better estimation of possible health outcomes. The difficulty in assessing the exact nature of Pb exposure is dependent not so much on problems with current analytical methodologies, but rather on the complex toxicokinetics of Pb within various body compartments (i.e., cycling of Pb between bone, blood, and soft tissues). If we are to differentiate more effectively between Pb stored in the body for years and Pb from recent exposure, information on other biomarkers of exposure may be needed. None of the current biomarkers of internal Pb dose have yet been accepted by the scientific community as a reliable substitute for a BPb measurement. This review focuses on the limitations of biomarkers of Pb exposure and the need to improve the accuracy of their measurement. We present here only the traditional analytical protocols in current use, and we attempt to assess the influence of confounding variables on BPb levels. Finally, we discuss the interpretation of BPb data with respect to both external and endogenous Pb exposure, past or recent exposure, as well as the significance of Pb determinations in human specimens including hair, nails, saliva, bone, blood (plasma, whole blood), urine, feces, and exfoliated teeth.

A comparative study based on gender and age dependence of selected metals in scalp hair

Levels of 10 metals (Ca, Mg, Fe, Zn, Cu, Mn, Cd, Co, Cr and Ni) in the scalp hair of male and female donors, with age groups between 3 and 100 years, were determined by ICP-AES. In total, 58 male and 30 female hair samples were analyzed in triplicate. The donors belonged to the rural area of district Chakwal, a well-known typical non-urban site in Pakistan. Calcium showed the highest concentration of 462 microg/g in the hair of males and 870 microg/g in those of females followed by Zn, at 208 and 251 microg/g for the two sexes. For male donors, Cd showed the lowest concentration (1.15 microg/g) while for female donors Co remained at minimum level (0.92 microg/g). The order of decreasing metal concentration in the hair of male donors was: Ca > Zn > Mg > Fe > Cu > Mn > Ni > Cr > Co > Cd while that for female donors it was: Ca > Zn > Mg > Fe > Cu > Mn > Cr > Ni > Cd > Co. The female group exhibited enhanced levels of all selected metals except Fe and Co in their hair as compared with the male counterparts. A strong bivariate positive correlation was found between Fe and Zn (r = 0.841) for the hair samples from male category while for the female category, strong positive correlations were observed between Ca-Mg (r = 0.617), Ca-Zn (r = 0.569), Ca-Mn (r = 0.565), Mg-Mn (r = 0.655), Cr-Cu (r = 0.655) and Cr-Ni (r = 0.685). The distribution of metals in the hair of donors with respect to different age groups was also investigated for both genders. The study showed that in case of males, the concentration of all selected metals decreased with increasing age except for Cu, Co and Cr. However, for females the hair metal levels increased with age, except for Co for which the concentration decreased with age. No appreciable change in the metal concentration was observed as a function of age for the combined sexes.

Human biomonitoring of cadmium and lead exposure of child-mother pairs from Germany living in the vicinity of industrial sources (hot spot study NRW)

Cadmium (Cd) and lead (Pb) exposure of children and their mothers living in the vicinity of industrial sources (metal refining) was assessed by a cross-sectional study performed in 2000. Study areas were the highly industrialized city of Duisburg and a rural area of North Rhine Westphalia, Germany. Exposure to ambient air concentrations of Cd and Pb was calculated from a Lagrange dispersion model using data sets from ambient air quality measurements. Cd in blood and urine and Pb in blood were measured by AAS. Mean age (years) was 6.4 (range 5.5-7.7) for children (n = 238) and 36 (range 23-48) for mothers (n = 213). A total of 49% of the children were males. Factors suspected to influence metal levels in blood or urine were obtained by questionnaire. Individual ambient Cd and Pb levels according to the home address ranged from 0.5 ng/m3 (Cd) and 0.03 microg/m3 (Pb) (rural area) up to 31.2 ng/m3 (Cd) and 0.73 microg/m3 (Pb) (industrialized area). Cd levels (geometric mean) in blood (0.13 and 0.10 microg/L) and urine (both areas 0.09 microg/L) of children did not differ between the two areas. Cd levels in blood and urine of mothers from the industrialized area were higher (blood 0.39 microg/L, urine 0.28 microg/L) than in those from the rural area (blood 0.25 microg/L, urine 0.25 microg/L). Pb levels in the blood of children from the industrialized area were higher (31 microg/L) than in those from the rural area (21 microg/L). Pb levels in the blood of mothers did not differ between the two areas (both 24 microg/L). Pb levels in blood showed a significant association between child and mother (n = 192; r = 0.26, p < 0.001). This did not apply for Cd in blood or urine. Regression analysis clearly revealed that Pb levels in ambient air were associated with Pb in the blood of children. Minor associations were also found between Cd in air and Cd in the blood of mothers and between Cd in air and urine of mothers.

Content of lead in human hair from people with various exposure levels in Lithuania

A study has been performed to estimate if hair lead (Pb) can be used assessing environmental and occupational exposure to the metal. From 1994-1997, 622 ceramic plant employees, 520 randomly selected controls from Kaunas without occupational exposure to Pb aged 18-64 years, and 380 10-13 year old children living in Kaunas participated in this study. The concentration of Pb in the hair samples was measured by atomic absorption spectrometry. The geometric mean of Pb in the hair of workers occupationally exposed to Pb was significantly higher than that in persons not exposed to the metal (7.6 microg/g, 95% CI = 6.5-8.7 for exposed workers, 3.2 microg/g, 95% CI = 2.8-3.6 for not exposed workers and 2.6 microg/g, 95% CI = 2.4-2.9 for randomly selected controls, p < 0.05). Pb content in hair of boys and girls was 2.9 microg/g (95% CI = 2.6-3.3) and 3.1 microg/g (95% CI = 2.6-3.6), respectively. Lead in hair was not related to gender. Multiple regression analysis in adults with age as a continuous variable showed a positive relationship between Pb in hair and age. Also different exposure levels were significantly related to Pb in hair. In men, a positive association was found between Pb in hair and smoking. The data obtained suggest that human hair could be used to identify lead exposure in epidemiological surveys.

Dietary intake of lead by children and adults from Germany measured by the duplicate method

The dietary lead intake was studied among children and adults from Germany. Two different age groups of children (A: 1.8, 1.3-3.0 years, B: 3.8, 1.8-5.2 years) and one group of adults (D: 40.9, 24-64 years) were from the highly industrialized Ruhr district and one group of children from the North Sea island Amrum (C: 3.9, 1.5-5.3 years). A total of 229 duplicate food portions were collected from 49 individuals between December 1994 and May 1995. Sampling period for each participant was either 3 (groups B and D) or 7 days (groups A and C). Lead levels in duplicate samples were measured by electrothermal atomic absorption spectrometry. The lead intakes (median, range) for the different groups were as follows: Group A: 0.21 (0.05-1.5) microgram/(kg bw.day), group B: 0.68 (0.06-1.6) microgram/(kg bw.day), group C: 0.29 (0.04-1.6) microgram/(kg bw.day) and group D: 0.26 (0.07-0.83) microgram/(kg bw.day). No value exceeded the provisional tolerable weekly intake (PTWI) of 25 micrograms/(kg bw.week) proposed by the WHO. The median and maximum of the different groups amounted to 7.2-16% and 16-36% of the PTWI, respectively. It is concluded that health risks due to dietary lead intake seem to be low in Germany.

Mercury concentrations in urine, scalp hair, and saliva in children from Germany

Mercury levels measured in urine, hair, and saliva of 245 German children (8-10 years old) are reported. Mercury concentrations in urine ranged between <0.1 and 5.3 microg/l [geometric mean (GM) 0.26 microg/l or 0.25 microg/g creatinine; median for both, 0.22 in microg/l and microg/g, respectively]. Using multiple linear regression analysis, two predictors have been found accounting for 25.3% of the variance of mercury levels in urine: the number of teeth with amalgam fillings (23.2%) and the number of defective amalgam fillings (2.1%). The mercury content in hair ranged from <0.06 to 1.7 microg/g (GM 0.18 microg/g; median 0.18 microg/g). The frequency of fish consumption, the smoking habits of the parents, and the age of the children accounted for 20.4% of the variance of mercury levels in hair. The correlation between the hair mercury content and urine mercury concentration was low (r=0.297). Mercury levels in saliva ranged between <0.32 and 4.5 microg/l (median 0.16 microg/l). The mercury concentration in saliva was below the limit of quantification of 0.32 microg/l in more than 70% of the samples. Mercury analysis in urine is suitable to estimate mercury exposure due to amalgam fillings, whereas hair mercury better reflects mercury intake by fish consumption. Up to now, saliva does not seem to be a suitable tool to monitor the mercury burden, at least not at low exposure levels.