Concentration of zinc in the hair of schoolchildren

Metallic elements in human hair from residents in smelting districts in northeast China: Environmental factors and differences in ingestion media

The health of residents in Huludao City is affected by the emissions of heavy metals from smelting, diet and atmospheric precipitation. This study investigated the concentrations of Hg, Cd, Pb, Cu and Zn in scalp hair samples from 259 residents of different ages and genders from five districts in Huludao City and examined the main factors for heavy metal exposure. Cd and Pb concentrations in hair samples exceeded the normal concentration ranges for human hair (Cd < 0.3 mg/kg; Pb < 9.3 mg/kg), and the highest Pb concentrations were found in subjects in the age range 0-15 years. Samples from men were higher in Cd and Pb compared to those for women. Workers from the Huludao zinc plant (HZP) had higher concentrations of all metals in their hair relative to other occupations except for Cu. Geographically, the highest Cd and Pb concentrations in hair were found for residents living in Daochi district (DCD) and the Zn plant district (ZPD), respectively. In smelting regions, the effects of dust ingestion on heavy metal exposure were more important than in non-smelting regions.

Distribution of metal and metalloid elements in human scalp hair in Taiyuan, China

This study investigated the levels of metal and metalloid elements (As, Ca, Cd, Cr, Cu, Fe, Hg, Mg, Ni, Pb, and Zn) in scalp hair samples collected from 161 people of different age and gender groups living in the six districts of Taiyuan, an industrial city with rich coal reserve in Shanxi province in China. Levels of most elements in the hair were high in the 26-40 age groups and increased with the length of residence. Calcium, Cr, Mg, Ni and Zn levels in the females' hair were significantly higher than those in the males' (p < 0.05). Element levels in the hair didn't have significantly differences between industrial and non-industrial districts because most of industry factories are in the upper wind position in Taiyuan, and contamination is prone to spread to non-industrial districts. The principal component analysis indicates that the main sources of these elements are mining activities, the neighboring stainless steel industry, and coal combustion. These results indicate that the industrial activities primarily contribute to the metal and metalloid pollution in Taiyuan, whereas numerous factors caused the metals accumulation in hair.

Gender as a key factor in trace metal and metalloid content of human scalp hair. A multi-site study

This multi-site study discusses the content of metals and metalloids (MM) in scalp hair of children, living in different environmental contexts, with the purpose of verifying if hair level of some MM is distinctively gender-specific. A total of 943 hair samples (537 females and 406 males) from adolescents were analyzed for their content of Al, As, Ba, Cd, Co, Cr, Cu, Li, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sr, U, V and Zn. Elemental quantification was performed by ICP-MS. The obtained data identified different metal distributions in adolescent girls which exhibited significantly higher hair concentrations of some trace metals, especially Sr, Zn and Ni, than boys. On the base of the median value, hair of female donors contained 3.8 times more Sr (6.6μg/g) than males (1.7μg/g). Highest concentrations of Zn in females were observed in samples from the mining area of Sardinia (587μg/g). Nickel showed significant differences resulting 2.5-fold higher in female hair. Regardless of the residence site, these elements resulted always significantly different (at p<0.01) between female and male indicating that gender is a confounding factor that has to be more extensively considered for a correct interpretation of metal profiles in human hair.

Biomarkers of Nutrition for Development (BOND)-Zinc Review

Zinc is required for multiple metabolic processes as a structural, regulatory, or catalytic ion. Cellular, tissue, and whole-body zinc homeostasis is tightly controlled to sustain metabolic functions over a wide range of zinc intakes, making it difficult to assess zinc insufficiency or excess. The BOND (Biomarkers of Nutrition for Development) Zinc Expert Panel recommends 3 measurements for estimating zinc status: dietary zinc intake, plasma zinc concentration (PZC), and height-for-age of growing infants and children. The amount of dietary zinc potentially available for absorption, which requires an estimate of dietary zinc and phytate, can be used to identify individuals and populations at risk of zinc deficiency. PZCs respond to severe dietary zinc restriction and to zinc supplementation; they also change with shifts in whole-body zinc balance and clinical signs of zinc deficiency. PZC cutoffs are available to identify individuals and populations at risk of zinc deficiency. However, there are limitations in using the PZC to assess zinc status. PZCs respond less to additional zinc provided in food than to a supplement administered between meals, there is considerable interindividual variability in PZCs with changes in dietary zinc, and PZCs are influenced by recent meal consumption, the time of day, inflammation, and certain drugs and hormones. Insufficient data are available on hair, urinary, nail, and blood cell zinc responses to changes in dietary zinc to recommend these biomarkers for assessing zinc status. Of the potential functional indicators of zinc, growth is the only one that is recommended. Because pharmacologic zinc doses are unlikely to enhance growth, a growth response to supplemental zinc is interpreted as indicating pre-existing zinc deficiency. Other functional indicators reviewed but not recommended for assessing zinc nutrition in clinical or field settings because of insufficient information are the activity or amounts of zinc-dependent enzymes and proteins and biomarkers of oxidative stress, inflammation, or DNA damage.

Associations of socio-demographic and behavioral variables with hair zinc of Vancouver preschoolers

Marginal zinc deficiency (MZD) exists in children of industrialized societies and impairs growth and development. MZD is believed to be one of the most common deficiencies, even though there is no data available on its global prevalence. This is partly because of the lack of sensitivity and specificity of serum zinc, the most commonly used biomarker of zinc status, to detect MZD. In children, MZD is always accompanied by a decrease in hair zinc. This cross-sectional study was designed to explore if there are any associations between some socio-demographic and behavioral variables with hair zinc status in an attempt to understand the social determinants of MZD and the profile of at risk children. Our citywide survey (n = 719) indicated a mean hair zinc of 116 ± 43 μg/g with 17% below the cutoff. Logistic regression analysis indicated that age, maternal education, number of adults at home, being described as "eating unhealthy", and Child Behavior Questionnaire scores of "activity level" as the significant predictors of hair zinc status. Our study provides important information on the hair zinc status of Vancouver preschoolers and some factors in children and their environment associated with hair zinc, which may help in better understanding of hair zinc as a biomarker of MZD.

Tissue zinc levels in a child with hypercalprotectinaemia and hyperzincaemia: A case report and a review of the literature

BACKGROUND

A girl suffering from a rare syndrome of unknown aetiology, termed hypercalprotectinaemia, was evaluated for tissue zinc status, because calprotectin is a protein which chelates Zn at multiple binding-sites, which might have affected the distribution of Zn in her body.

METHODS

Measurement of serum, urine, hair and nail zinc (Zn) concentration, complemented with measurement of total Zn in ultrafiltrates of plasma.

RESULTS

Her serum Zn concentration was 105-133 μmol/L. Zn levels in her hair (102 μg/g), nail (90 μg/g) and urine (3-12 μmol/L; 20-80 μg/dL) were all at the lower end of the reference intervals described in the sparse literature. Zn concentrations in ultrafiltrates of plasma were below the detection limit (<100 nmol/L). Thus, the elevated serum Zn did not translate into a similarly increased level of Zn in any of the tissues tested, nor in free Zn concentrations. Instead it appeared to be a result of Zn being chelated to binder proteins, most probably calprotectin.

CONCLUSION

Her grossly elevated serum calprotectin concentration is probably able to raise circulating total Zn concentrations without raising ionized concentrations, but this Zn remains confined to the circulating blood as well as to excreted body fluids, particularly faeces.

Concentration and reference interval of trace elements in human hair from students living in Palermo, Sicily (Italy)

Trace element contents in specimens of hair collected from 137 children aged 11-13 years old, living in Palermo (Sicily, Italy) were determined by ICP-MS. This work reports analytical data for the following 19 elements: Al, As, Ba, Cd, Co, Cr, Cu, Li, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sr, U, V and Zn. The most abundant chemical elements were zinc and copper (Zn > Cu), with concentrations exceeding 10 μg/g (Zn = 189.2 μg/g; Cu = 22.9 μg/g). Other elements with concentrations greater than 1 μg/g were, in order of abundance, Al>Sr>Ba>Pb. The remaining elements were all below 1 μg/g. The average elemental concentrations in hair were statistically compared by Kolmogorov-Smirnov's test taking children's gender into account. Al, Ba, Cr, Li, Rb, Sb, Sr, V and Zn were statistically different according to gender, with significance p < 0.001. This study thus confirms the need for hair analysis to differentiate female data from those of males. IUPAC coverage intervals and coverage uncertainties for trace elements in the analysed hair samples are also reported.

Age-based differences in hair zinc of Vancouver preschoolers

Marginal zinc deficiency (MZD), the subclinical stage of zinc deficiency, is common in industrialized societies. Serum zinc, the most common biomarker of zinc status, lacks sensitivity and specificity to diagnose this deficiency. Hair zinc, however, is sensitive and specific enough to detect MZD in children. Differences in hair zinc associated with age and sex have been reported. These differences have not been investigated thoroughly; therefore, interpretation of the results of hair analyses is difficult. This cross-sectional study was designed to examine the hair zinc status of a group of Vancouver preschoolers (24-71 months) and assess the age- and sex-based differences in their hair zinc. Hair samples were obtained (n = 719) and analyzed for zinc using inductively coupled plasma mass spectrometry. Our results indicated a mean hair zinc of 115 +/- 43 microg/g with 17% below the low hair zinc cutoff (70 microg/g). Boys and girls had comparable mean hair zinc, while girls had a significantly higher occurrence of low hair zinc than boys (21% vs. 12%). Children <4 years of age had significantly lower mean hair zinc and higher rate of low hair zinc compared to children > or =4. Our study provides important reference values for the hair zinc of healthy North American preschoolers.

Determination of copper and zinc levels in human hair: influence of sex, age, and hair pigmentation

The Cu and Zn levels of both 607 men (1-85 y old) and 649 women (1-92 y old) were determined by atomic absorption spectrometry. Sex does not influence Cu (14.89 + or - 0.89 mu g/g and 15.26 + or - 0.79 mu g/g hair for males and females, respectively) and Zn contents (200.97 + or - 9.68 mu g/g for men and 209.81 + or - 9.49 mu g/g hair for women). Age influences Cu and Zn concentrations, but only significantly in females: Cu levels decrease over 60 y of age; whereas Zn levels increase significantly from age groups 2-5 to 20-40 years. Hair color influences Cu concentrations in both males and females. In males, white hair contains less Cu than black hair; in females, white hair's Cu levels are significantly lower than those of dark blond, red, light brown, and brown hair. There are no significant differences in Zn concentrations with respect to different hair colors, in either males or females.

Trace elements nutritional status. Use of hair as a diagnostic tool

In this study, hair levels of Cu and Zn were determined in healthy male and female individuals (n = 192) ages 3.6-14.5 yr and the correlations with Cu and Zn daily intakes were examined. Determinations of Cu and Zn concentrations were performed by way of atomic absorption spectrometry and X-ray fluorescence. Nutritional data were collected with the aid of an individual questionnaire. Statistical analysis revealed no effect of age and sex either on Cu concentrations in hair or on Cu daily intakes. Zn concentrations were significantly higher in hair of both pubescent males and females compared with prepubescent individuals. There was no influence of age on Zn daily intake in males, however, whereas pubescent girls had a lower intake than males. Correlation coefficients between Cu concentrations in hair and daily nutritional intakes calculated for males and females were r = 0.1694 and r = 0.1677, respectively; those for Zn were r = -0.2223 (p < 0.05) in males and r = -0.2787 (p < 0.01) in females. These data confirm that the analysis of Zn in hair represents an addition to conventional materials in the assessment of the nutritional status of groups of individuals.

The influence of color, age, and sex on the content of zinc, copper, nickel, manganese, and lead in human hair

The hair of 132 healthy subjects between 6 and 40 yr old living in the Veneto region in Italy was analyzed by means of HPLC method in order to determine the presence of zinc, copper, nickel, manganese, and lead. The collected samples were subdivided on the basis of age (6-11 and 19-40 yr), and sex and color (black, red, brown, and blond). From the data some evident differences were emphasized. In female hair the content of metals was higher than in male hair independently of color. Blond hair gave the lowest concentration values of the elements studied independently of sex. The maximum amount of the metals was found generally in black hair, followed by red and brown hair. Age seems to have a different influence, with the copper element decreasing appreciably in brown and blond female hair as the age of the subjects increased.

Hormonal effects of zinc on growth in children

Zinc deficiency impairs the metabolism of thyroid hormones, androgens, and above all growth hormones. In view of their important role in growth, it is not surprising to find growth disorders associated with zinc deficiency. Stunted growth linked to zinc deficiency is found during gestation, and also in the newborn and children up to adolescence. Depending on the country, 5-30% of children suffer from moderate zinc deficiency, responsible for small-for-age height. Zinc supplementation has proven effective in many studies, mainly in children where zinc deficiency has first been found. Finally, zinc supplementation makes it possible in certain cases to overcome resistance to growth hormone treatment.

Hair zinc of young children from rural and urban areas in North Rhine-Westphalia, Federal Republic of Germany

Hair zinc levels were estimated by atomic absorption spectrophotometry in 474 children, aged 3-7 years, from 11 kindergartens in a highly industrialized and polluted area (Duisburg) and 8 kindergartens in a rural area of North Rhine-Westphalia. The mean hair zinc level amounted to 118 micrograms/g, increasing between the 4th and 7th year of life. At all ages the values from the urban toddlers were lower than from rural toddlers, and in both regions they were higher in winter than in summer. Children with frequent upper respiratory tract infections (greater than 6 infections/year) showed significantly lower zinc hair values, independent of their age. Low hair zinc values (below 70 micrograms/g) were frequently found, raising the question as to whether this is a normal, age-related phenomenon, or whether it indicates a suboptimal zinc status of young children from North Rhine-Westphalia.

Trace element levels in hair of eight-year-old children

A study of trace element levels in hair was performed on 183 eight-year-old schoolchildren living in Bijlmermeer, a suburb of Amsterdam, the Netherlands. Microlevel-elements, such as Au, Co, Ag, Se and Cd, and macrolevel-elements, such as Pb, Cu, Fe and Zn, were analyzed using the NAA and AAS methods. The total group of children was divided into subgroups, according to ethnic origins: Caucasian boys and girls, Hindustani children and a Surinamese rest group. The relation between element levels in hair and nutritional status, anthropometric and haematological variables were studied. Most levels corresponded reasonably with literature data. The iron in hair may be positively related to daily dietary intake of iron.

Zinc and the skin

Zinc is an essential trace element integrally involved in a wide range of metabolic processes required for tissue growth and repair as well as being necessary for maintaining host defences. Zinc deficiency can occur from lack of adequate dietary intake, decreased intestinal absorption, and increased losses in the gastrointestinal tract, urine, and sweat. The clinical signs of zinc deficiency can present in a florid manner with dermatitis, alopecia, and diarrhea, or they can be chronic changes with dwarfism and hypogonadism or, the signs may be barely perceptible with low growth rates and hypogeusia. As with all nutritional deficiencies, the possibility of its existence must be considered before the diagnosis can be made. It is not known how severe zinc deficiency must be or how long it has to be present before the characteristic rash appears. However, as biochemical changes of zinc deficiency occur before any clinical changes do, it is likely that metabolic processes have been affected before the rash heralds the presence of zinc deficiency.

Zinc status of Libyan children -- a pilot study

Hair zinc has been investigated in children of North and South Libya. The hair zinc content amounts to 213 +/- 36 micrograms/g in newborns. There is no difference between the values of newborns from North Libya and newborns from South Libya. The hair zinc values decrease during infancy. In toddlers and school-children the hair zinc content is 88 +/- 35 micrograms/g, 89 +/- 25 micrograms/g resp. These values are as low as those reported in American children with low height percentiles or nearly as low as those found in dwarfs with poor zinc status from Egypt and Iran.

The zinc, copper, and manganese status of children with malabsorption syndromes and inborn errors of metabolism

The zinc, copper, and manganese status of seven children with malabsorption syndromes of varied etiology (MVE) and 12 with inborn errors of metabolism (IEM) receiving semi-synthetic diets was investigated using serum and hair trace element concentrations, dietary trace element intakes, and anthropometric measurements as the principal indices. The hair zinc levels of both test groups and hair manganese levels of the IEM group were significantly lower (p<0.05) than those of their respective healthy controls matched by age, sex, and geographic location, despite comparable dietary zinc and manganese intakes in test and control subjects. Four subjects from the malabsorption and five from the inborn errors group had hair zinc levels below 100 μg/g (range 30-88 μg/g). Of these nine subjects, serum zinc levels were determined for six, and five were less than normal (range 64-74 μg/dL). In contrast, the copper status of the MVE and IEM subjects, as indicated by hair and dietary copper levels, was not lower than the controls. Mean serum copper levels were 136±30 and 171±40 μg/dL for the IEM and MVE groups, respectively. Levels for the MVE subjects were higher than published normal values. The suboptimal zinc and manganese status observed in some of these test subjects probably arose from malabsorption and decreased availability of dietary zinc and manganese. However, the zinc depletion was not severe enough to result in linear growth retardation.