Lead levels in deciduous teeth of children in Bahrain

Historic variation of trace elements in pinnipeds with spatially segregated trophic habits reveals differences in exposure to pollution

Marine mammals and the ecological functions they provide to coastal and pelagic ecosystems are increasingly threatened by the intensification of anthropogenic impacts. The Uruguayan coastline throughout the 20th century, like other coastal environments worldwide, has been the sink of a variety of trace metals derived from the rapid urbanization and industrialization of related land areas. This coastline is inhabited by two species of pinnipeds trophically and spatially segregated. Otaria byronia feeds in coastal environments while Arctocephalus australis preys mainly offshore. The present study aimed to analyze historic changes in concentrations of trace elements in teeth of both species from 1941 to the present day. We analyzed the dentin of 94 canine teeth using stable isotope analysis (δ¹³C) and ICP-MS to determine their feeding areas and the concentration of 10 trace elements (Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) respectively. The concentration of Cr was significantly higher during '70-'80s, in both species coinciding with tannery industry development. Both species of pinnipeds have been differentially exposed to trace elements depending on their feeding area. A pelagic diet, possibly based on squid, increased the concentration of Cd in A. australis, while O. byronia has been more exposed to anthropogenic Pb and Cu associated to a costal and more benthic diet. Our results highlight dentin as a reliable matrix for historic studies on the exposure to trace elements. In light of our results, the O. byronia's declining population could be the result of the synergistic effects of trace elements together with other ecological pressures faced in their environment.

Relating tooth- and blood-lead levels in children residing near a zinc-lead smelter in India

BACKGROUND

Lead toxicity particularly affects children because of their increased capacity for absorption and retention. Blood-lead (BPb) levels reflect recent exposure and are of limited value in predicting neurotoxicity, whereas in teeth, lead accumulates over a long period of time and provides an integrated record of lead exposure from intrauterine life until the teeth are shed.

AIM

The present study aimed to relate tooth-lead (TPb) and BPb levels in children residing near a zinc-lead smelter in India, and to evaluate the effectiveness of primary teeth as bioindicators of life-long lead exposure.

DESIGN

The lead levels in primary teeth and blood of 100 children aged between 5 and 13 years, living in the proximity of a zinc-lead smelter were measured by atomic absorption spectrophotometry. The mean levels were tabulated based on village, age, sex and tooth type, and analysed statistically.

RESULTS

The mean BPb level was significantly influenced by proximity to the lead source, but not by age or sex. There was no consistent pattern of correlation between BPb and TPb levels.

CONCLUSION

Primary teeth showed significantly high lead levels compared to blood; they reflect cumulative exposure to lead and prove to be better indicators of body lead burden.

Tooth element levels indicating exposure profiles in diabetic and hypertensive subjects from Mysore, India

Element contents of teeth elucidate exposure nature, but less is known about association of tooth element concentrations of diabetics and hypertensives with exposure profile. Present study aims to estimate copper, chromium, iron, zinc, nickel, and lead concentrations in the permanent teeth of control, diabetic, and hypertensive subjects from Mysore. The results show that lead levels of teeth (Pb-T) are higher in the hypertensives and diabetics, whereas copper levels of teeth (Cu-T) are lower in the hypertensives and users of stainless steel utensils than that of controls and users of mixed utensils. The elevated Cu-T levels found in the users of mixed utensils that being made of several metals are ascribed to leaching effect of sour and spicy food of Indian cuisine. The element levels were influenced by diet (Zn-T), place of living, sex and income (Pb-T) of the subjects, but not by age, drinking water from different sources, and certain habits viz., smoking, alcohol consumption, chewing betel, and nut. Thus, it is evident that high Pb-T and low Cu-T levels may be related with diabetes and hypertension and high Pb-T and Cu-T levels, respectively, in the urbanites, and the users of mixed utensils may show different exposure profiles from environment and utensils.

Dental lead levels in children from two different urban and suburban areas of Turkey

The lead content of shed primary teeth has proved to be a reliable measure of cumulative lead exposure in children as it is an indicator of the degree of exposure over several years, from in utero life to loss of the tooth. Totally 297 shed deciduous teeth were collected from 263 children between ages 4 and 15 to determine the level of lead exposure in Ankara and Balikesir in Turkey. Ankara is the capital of Turkey and characterized by heavy traffic and high air pollution. On the other hand, Balikesir has less traffic. Balikesir-Centre (R) had the highest mean (SD) lead level (1.77+/-1.03microg/g) whereas Ankara-Centre (U) had the lowest level (1.30+/-0.59microg/g). We could not observe a statistically significant difference between urban and suburban regions (Table 1), and in terms of type of tooth, incisors had a statistically significant higher lead level than canines and molars (p<0.05, Table 2). No difference was observed between boys and girls and the accumulation of lead in teeth (p<0.05, ).

Environmental influences on the trace element content of teeth--implications for disease and nutritional status

The aim of this study was to compare the trace element content of children's primary teeth from Uganda and the UK. The Ugandan teeth were from children living in an area where endomyocardial fibrosis (EMF), a cardiac disease, is prevalent. The latter has been putatively linked to insufficient magnesium intake and excess cerium exposure. Primary teeth were collected from 21 Ugandan and 27 UK children. The crowns and roots of the teeth were separated and the former digested and analysed for several major and trace elements by inductively coupled plasma mass spectrometry (ICP-MS) and atomic emission spectrometry (ICP-AES). In addition, the enamel and dentine of eight UK and seven Ugandan primary teeth were isolated via density separation and analysed as above. The data were assessed using non-parametric statistical tests. The Ugandan teeth contained significantly (P < 0.05) greater concentrations of strontium, barium, cerium, lanthanum, praseodymium and significantly less zinc than the UK teeth. No significant difference in the concentrations of aluminium, calcium, copper, magnesium, lead and uranium were found. Analysis of enamel and dentine demonstrated that the former was enriched with several elements including cerium. It is concluded, that the environment, influences the trace element content of primary teeth and this may be useful for monitoring nutritional status. With respect to a geochemical cause for EMF, there is no positive evidence that EMF in Uganda is associated with reduced magnesium and increased cerium uptake in primary teeth. This does not, however, exclude cerium from playing a role in the aetiology of EMF.

Lead-associated deficits in stature, mental ability and behaviour in children in Karachi

This study was conducted to evaluate the cumulative and steady-state lead burden in children from Karachi, an area of high lead exposure, and to assess the degree of damage to physical growth and mental ability related to lead exposure. A cross-sectional survey was conducted in seven primary schools from around Karachi. Shed primary teeth and blood samples were collected from students of grades I to III (age range 6-10 years) and were analysed for lead by atomic absorption spectrophotometry. Haemoglobin concentration, height, weight and head circumference were measured. IQ was estimated using Raven's Standard Progressive Matrices. Classroom behaviour was rated by teachers and school performance was estimated from the percentage mark in a school examination taken just before the date of the IQ test. Complete data were available for 138 children. Over 80% of children had lead levels above the safety limit set by the United States Centers for Disease Control and Prevention. The blood lead levels in boys did not differ significantly from that in girls. Significant differences were observed between the schools. Univariate analysis showed negative association of blood lead with haemoglobin, IQ and height. Tooth lead was negatively associated with height, classroom behaviour and performance. When adjusted for other confounding variables, blood lead was negatively associated with haemoglobin and IQ, whereas tooth lead was negatively associated only with classroom behaviour. Height was negatively associated with blood or tooth lead. These results were further supported when the upper and lower quintiles for blood or tooth lead were compared. Tooth lead level was not a better marker of lead poisoning than blood lead level in our study population. These data demonstrate the association of increased lead with impaired learning and adverse behaviour in Karachi children and call for strict government regulations to limit environmental lead burden.

Lead levels in primary teeth of children in Karachi

The majority of children in Karachi have blood lead levels above 10 micrograms/dl, the upper safety limit set by the United States Centers for Disease Control and Prevention. A study was undertaken to evaluate chronic lead exposure in children by measuring lead levels in shed primary teeth collected from primary school children in Karachi. A total of 309 teeth were collected from nine different schools, and analysed for lead content by atomic absorption spectrophotometry with electrothermal atomization. The mean (SD) age of the subjects was 7.6 (1.2) years and the mean lead level was 5.78 micrograms/g of whole tooth (dry weight), ranging from 0.42 to 39.75 micrograms/g. Incisor teeth had a significantly higher mean (SD) lead level, 6.42 (4.19) micrograms/g, than canines and molars which contained 4.91 (5.12) micrograms and 4.50 (2.67) micrograms lead whole tooth (dry weight), respectively. Significant differences were observed between different schools. No difference was observed between boys and girls and the accumulation of lead in teeth was not correlated with chronological age.