Cognitive abilities, androgen levels, and body mass index in 5-year-old children

This study explores the potential relationship between a series of cognitive abilities and testosterone, dehydroepiandrosterone (DHEA), androstenedione, and body mass index (BMI) measurements in 5-year-old children. 60 boys and 69 girls were administered a test (K-BIT) which provided measurements of fluid intelligence (Matrices subtest), crystallized intelligence (Vocabulary subtest), and IQ composite (the combination of the two subtests); a sub-sample of 48 boys and 61 girls was also subjected to diverse tests related to theory of mind (affective labeling, appearance-reality distinction, display rules, and false belief). Testosterone, DHEA, and androstenedione levels were measured using an enzyme immunoassay technique in saliva samples. An analysis of variance failed to reveal any significant differences between boys and girls in any of the cognitive abilities assessed. The correlation analysis revealed a positive relationship between fluid intelligence and testosterone levels in boys, a negative relationship between crystallized intelligence and androstenedione levels in girls, and between affective labeling and androstenedione levels in boys. A multiple regression analysis indicated that androstenedione and BMI were the best predictors for some of the cognitive abilities assessed.     

Gender differentiations of cognitive-motor functioning in prepubertal and pubertal children

The aim of this study was to determine cognitive and motor status factors in female and male children aged 10-14, as well as developmental and/or integration functions according to gender. The study included 162 girls and 134 boys aged 10-14, divided into four groups: 84 girls aged 10-12 (mean age 11.26, SD 0.68), 84 boys aged 10-12 (mean age 11.41, SD 0.50), 78 girls aged 13-14 (mean age 13.52, SD 0.63) and 50 boys aged 13-14 (mean age 13.21, SD 0.53). The significance of quantitative differences between boys and girls in the overall system of variables was defined based on the results of canonic discriminant analysis of variance, and within each variable based on the results on univariate analysis of variance (ANOVA). In the younger age group (10-12 years), girls were superior to boys in a test assessing flexibility (Seated straddle stretch), whereas, compared to girls, boys had greater strength of the trunk (Crossed-arm sit-ups), greater explosive strength ofjump and sprint type (Standing broad jump and 20 m dash), and coordination (Obstacle course backwards and Steps laterally). In the older age group (13-14 years) differences in flexibility were even more prominent in favor of girls, whereas the differences in explosive strength increased in favor of boys, especially of the throwing type with better agility (Steps laterally), balance (Board balance) and greater static strength of arms and shoulders (Bent-arm hang). In order to determine qualitative differences between pubertal and prepubertal girls and boys, the matrix of variable inter-correlations was factorized by the procedure of principal components procedure, that were then transformed to promax solution. The results showed that cognitive functioning had a significant role in the motor efficacy of girls and boys aged 10 to 14. In the age group of 10-12 years, in females, cognitive functioning is related to the motor system which integrates the regulation of muscle tone with agility/coordination, whereas in males there is a relation between cognitive abilities and the regulator of speed of upper extremities movement frequency. In the age group of 13-14 years, in females, cognitive functioning is involved in forming the factors for regulation of coordination and the intensity of energy mobilization in lower extremities, and to some degree, in the factor for regulation of intensity of energy mobilization in upper extremities and strength of the trunk, whereas in males the integration of synergetic regulation of movement in terms of balance and agility in terms of speed of direction change is carried out with significant involvement of cognitive abilities.     

Influence of cognitive load on the body functional state in children aged 9 to 12 years during early stages of puberty

This article analyzes heart rate variability (HRV), the glucocorticoid function of adrenal glands, and brain electrical activity (EA) in children aged 9 to 12 years to study their functional state during early stages of puberty. The cognitive load (mental arithmetic) caused low-frequency waves in the heart rate spectrum in all subjects, regardless of the puberty stage and gender. With respect to the age range under study, the hormonal response to the arithmetic test, expressed in a decrease in the level of cortisol, was observed in boys only at the third stage of puberty. The visual analysis of the background electrical encephalogram showed frequent generalized bilateral and synchronous changes in the electrical activity (EA) in the form of diencephalic signs in children. The features of the relationship between the autonomic nervous system and the hypothalamic pituitary-adrenal system have been revealed in children aged 9 to 12 years during cognitive load. The closest correlations between HRV indices and cortisol levels have been found in girls at the first stage and boys at the third stage of puberty.     

The role of chronotype,gender, test anxiety,and conscientiousness in academic achievement of high school students

Previous findings have demonstrated that chronotype (morningness/intermediate/eveningness) is correlated with cognitive functions, that is, people show higher mental performance when they do a test at their preferred time of day. Empirical studies found a relationship between morningness and higher learning achievement at school and university. However, only a few of them controlled for other moderating and mediating variables. In this study, we included chronotype, gender, conscientiousness and test anxiety in a structural equation model (SEM) with grade point average (GPA) as academic achievement outcome. Participants were 158 high school students and results revealed that boys and girls differed in GPA and test anxiety significantly, with girls reporting better grades and higher test anxiety. Moreover, there was a positive correlation between conscientiousness and GPA (r = 0.17) and morningness (r = 0.29), respectively, and a negative correlation between conscientiousness and test anxiety (r = –0.22). The SEM demonstrated that gender was the strongest predictor of academic achievement. Lower test anxiety predicted higher GPA in girls but not in boys. Additionally, chronotype as moderator revealed a significant association between gender and GPA for evening types and intermediate types, while intermediate types showed a significant relationship between test anxiety and GPA. Our results suggest that gender is an essential predictor of academic achievement even stronger than low or absent test anxiety. Future studies are needed to explore how gender and chronotype act together in a longitudinal panel design and how chronotype is mediated by conscientiousness in the prediction of academic achievement.     

Analysis of cognitive and motor functioning during pubertal development: a new approach

We investigated cognitive-motor abilities in 303 (156 female) school children from Zagreb, Croatia, in the age span 10 to 14 years using a newly developed chronometrical reactionmeter system (CRD). The following tests were applied: CRD-311 (simple visual discrimination of signal location), CRD-324 (short-term memory actualisation), CRD-21 (simple convergent visual orientation), and CRD-11 (arithmetically conceptualised/operationalised convergent thinking). In both gender a statistically significant age related improvement of the performance for time related parameters (minimum time of test item solving (MT), total ballast (TB), and total time of test solving (TT) was observed. In contrast, the number of errors (NE), which was the only non-time related parameter tested, did not significantly change with age. Significant differences between boys and girls were observed for the time related parameters TB and MT. TB was significantly lower in girls, whereas boys tended to be faster in MT measurements. In TT as a composed measure of the mentioned parameters, no major differences were observed. We conclude that the CRD system is a new useful tool for investigating the complexity of cognitive-motor abilities in children. Our cross-sectional study demonstrated that the time-related parameters were significantly affected by age and gender during puberty.     

Positive Effect of Large Birth Intervals on Early Childhood Hemoglobin Levels in Africa Is Limited to Girls: Cross-Sectional DHS Study

Background

Short birth intervals are independently associated with increased risk of adverse maternal, perinatal, infant and child outcomes. Anemia in children, which is highly prevalent in Africa, is associated with an increased risk of morbidity and mortality. Birth spacing is advocated as a tool to reduce anemia in preschool African children, but the role of gender differences and contextual factors has been neglected. The present study aims to determine to what extent the length of preceding birth interval influences the hemoglobin levels of African preschool children in general, as well as for boys and girls separately, and which contextual factors thereby play a crucial role.

Methods and Findings

This cross-sectional study uses data from Demographic and Health Surveys (DHS) conducted between 2003 and 2011 in 20 African countries. All preschool children aged 6–59 months with a valid hemoglobin measurement and a preceding birth interval of 7–72 months as well as their corresponding multigravida mothers aged 21–49 years were included in the study. Hemoglobin levels of children and mothers were measured in g/l, while birth intervals were calculated as months difference between consecutive births. Multivariate analyses were done to examine the relationship between length of preceding birth interval and child hemoglobin levels, adjusted for factors at the individual, household, community, district, and country level. A positive linear relationship was observed between birth interval and the 49,260 included children’s hemoglobin level, whereby age and sex of the child, hemoglobin level of the mother, household wealth, mother’s education and urbanization of place of residence also showed positive associations. In the interaction models, the effect of a month increase in birth interval is associated with an average increase of 0.025 g/l in hemoglobin level (P = 0.001) in girls, while for boys the effect was not significant. In addition, for girls, the effect of length of preceding birth interval was highest in young mothers and mothers with higher hemoglobin levels, while for boys, the highest effect was noticed for those living in more highly educated regions. Finally, significantly higher hemoglobin levels of girls compared to boys were observed at birth but with increasing age, the sex difference in hemoglobin level gradually becomes smaller.

Conclusions

A longer birth interval has a modest positive effect on early childhood hemoglobin levels of girls, and this effect is strongest when their mothers are in their early twenties and have a high hemoglobin level. Remarkably, although the physiological iron requirement is higher for boys than girls, birth spacing has little influence on hemoglobin levels of preschool boys. We speculate that the preference for male offspring in large parts of Africa significantly influences nutritional patterns of African preschool boys and girls, and as such also determines the different effect of birth spacing. Finally, gender aspects should be considered in intervention programs that aim to improve anemia in African children.     

Cross-sectional comparisons of BMI and waist circumference in British children: mixed public health messages

Research suggests that there has been a leveling off in obesity prevalence occurring in the child population. However, a concern with the evidence base is that all of the studies have relied upon the use of BMI. The purpose of this study was to compare waist circumference (WC), BMI, and waist-to-height ratio (WHtR) data in three different sample of children (total number: 14,697) typically aged 11-12 years. Obesity prevalence defined by BMI did not change significantly between measurement years (2005 boys 20.6%, girls 18.0%; 2006 boys 19.3%, girls 17.3%; 2007 boys 19.8%, girls 16.4%). Obesity prevalence defined by WC was considerably higher especially, in girls (2005 boys 26.3%, girls 35.6%; 2006 boys 20.3%, girls 28.2%; 2007 boys 22.1%, girls 30.1%). The prevalence of children defined as "at risk" according to WHtR (2005 boys 23.3%, girls 21.1%; 2006 boys 16.7%, girls 15.6%; 2007 boys 17.6%, girls 17.2%) was found to be between obesity prevalence, estimated using BMI and WC. This data are the most up to date collection that includes BMI and WC in three large samples of children and clearly demonstrates inconsistencies between different measurements based on current classification systems. There is a need to understand the relationship between BMI and WC, with growth and health risk to establish a consistent public health message that is easily understood by the public.     

Negative associations between corpus callosum midsagittal area and IQ in a representative sample of healthy children and adolescents

Documented associations between corpus callosum size and cognitive ability have heretofore been inconsistent potentially owing to differences in sample characteristics, differing methodologies in measuring CC size, or the use of absolute versus relative measures. We investigated the relationship between CC size and intelligence quotient (IQ) in the NIH MRI Study of Normal Brain Development sample, a large cohort of healthy children and adolescents (aged six to 18, n = 198) recruited to be representative of the US population. CC midsagittal area was measured using an automated system that partitioned the CC into 25 subregions. IQ was measured using the Wechsler Abbreviated Scale of Intelligence (WASI). After correcting for total brain volume and age, a significant negative correlation was found between total CC midsagittal area and IQ (r = −0.147; p = 0.040). Post hoc analyses revealed a significant negative correlation in children (age<12) (r = −0.279; p = 0.004) but not in adolescents (age≥12) (r = −0.005; p = 0.962). Partitioning the subjects by gender revealed a negative correlation in males (r = −0.231; p = 0.034) but not in females (r = 0.083; p = 0.389). Results suggest that the association between CC and intelligence is mostly driven by male children. In children, a significant gender difference was observed for FSIQ and PIQ, and in males, a significant age-group difference was observed for FSIQ and PIQ. These findings suggest that the correlation between CC midsagittal area and IQ may be related to age and gender.     

Household wealth and gender gap widening in height: Evidence from adolescents in Ethiopia,India, Peru,and Vietnam

This study investigates the relationship between household wealth and child height utilizing longitudinal data on 7150 children from Ethiopia, India, Peru, and Vietnam. The concept of conditional wealth is applied to separate the influence of wealth in early childhood. Conditional wealth is the change in wealth that was unpredicted at the age of 5 years. This study finds two dimensions of heterogeneity in the wealth-gradient of adolescent height: gender and stunting status at the age of 5 years. For all four countries in the study, the effect of conditional wealth on adolescent height is stronger for boys than for girls. The estimates for the pooled sample indicate that after the age of 5 years, the growth of children who were stunted at that age is significantly more responsive to conditional wealth than the growth of non-stunted children. The analysis results show that for boys in Ethiopia, a one-standard-deviation increase in preadolescence wealth is associated with an increase of 1 cm (standard error [SE]: 0.3) in height at the age of 15 years. For boys in the Indian state of Andhra Pradesh, Peru, and Vietnam, the corresponding figures are 1.1 cm (SE: 0.4), 1.8 cm (SE: 0.4), and 1.2 cm (SE: 0.4), respectively. The effect of preadolescence wealth on adolescent height is not statistically significant for girls, except in some regions. Overall, the results suggest that household wealth in preadolescence disproportionately benefits the male population in these countries when using height as a proxy for health.     

The relationship of lean limb volume to performance in the handgrip and standing long jump tests in boys and girls, aged 11.6–13.2 years

Twenty-three girls and 19 boys performed the handgrip and standing long jump (SLJ) tests. Their total forearm and leg volumes were calculated from circumference and length measurements and the lean volumes (bone + muscle) were calculated by making allowance for skinfold thickness. Although the boys were older than the girls (12.8 and 12.4 years), there was no significant difference in their heights or body masses. The absolute performances of the boys were superior to those of the girls in both tests (handgrip 234 and 205 N and SLJ 1.53 and 1.34 m), but when jumping performance was expressed as distance x body mass, there was no significant difference. In both tests, performance in terms of unit lean limb volume showed no significant gender difference. When performance was related to lean limb volume, both boys and girls showed a linear relationship in the two tests, with no significant difference between them. This absence of a gender difference contrasts with the results of a previous study on young adults and comparison shows that the relationships between lean limb volume and performance in the two tests for both boys and girls lie just below those of the young, adult females. The difference between the girls and the young adult females was just significant in the handgrip (p less than 0.05), but not significant in the SLJ (p greater than 0.25), whereas the differences between the boys and young adult males were significant (p less than 0.01) in both tests. Thus it would appear that a gender difference in the performance of skeletal muscle develops during adolescence and possible contributory factors are discussed.     

Gender, culture, and sex-typed cognitive abilities

Although gender differences in cognitive abilities are frequently reported, the magnitude of these differences and whether they hold practical significance in the educational outcomes of boys and girls is highly debated. Furthermore, when gender gaps in reading, mathematics and science literacy are reported they are often attributed to innate, biological differences rather than social and cultural factors. Cross-cultural evidence may contribute to this debate, and this study reports national gender differences in reading, mathematics and science literacy from 65 nations participating in the 2009 round of the Programme for International Student Assessment (PISA). Consistently across all nations, girls outperform boys in reading literacy, d = −.44. Boys outperform girls in mathematics in the USA, d = .22 and across OECD nations, d = .13. For science literacy, while the USA showed the largest gender difference across all OECD nations, d = .14, gender differences across OECD nations were non-significant, and a small female advantage was found for non-OECD nations, d = −.09. Across all three domains, these differences were more pronounced at both tails of the distribution for low- and high-achievers. Considerable cross-cultural variability was also observed, and national gender differences were correlated with gender equity measures, economic prosperity, and Hofstede’s cultural dimension of power distance. Educational and societal implications of such gender gaps are addressed, as well as the mechanisms by which gender differences in cognitive abilities are culturally mediated.     

Fetal growth: boys before girls

At term birth, boys are heavier than girls. This difference is thought to be generated in part by androgen action; its time course has not been deciphered. Androgen action may not only increase weight gain, but may also alter its time course. We have tested this hypothesis by examining the difference in gestational age of 281,894 boys and girls with weights between 500-4,749 g. The age at which children are born with a given weight was found to depend on gender: boys were consistently younger than girls (p < 0.001), the age difference being most pronounced in the lower birth weight classes. Thus, the gender difference in fetal growth appears to be rather pronounced before the third trimester and relatively less marked towards term. In conclusion, the male conceptus seems to grow not only more, but also earlier than the female. Hence, some critical time windows of development may be slightly different in boys and girls, and this phenomenon may be one of the bases for gender differences in the sensitivity to fetal programming. Copyrightz1999S. KargerAG,Basel     

Gender bias in nineteenth-century England: Evidence from factory children

Gender bias against girls in nineteenth-century England has received much interest but establishing its existence has proved difficult. We utilise data on heights of 16,402 children working in northern textile factories in 1837 to examine whether gender bias was evident. Current interpretations argue against any difference. Here our comparisons with modern height standards reveal greater deprivation for girls than for boys. Discrimination is measured in girls’ height-for-age score (HAZ) falling eight standard errors below boys’ at ages 11, 11.5 and 12 years of age, capturing the very poor performance of factory girls. But this result cannot be taken at face value. We query whether modern standards require adjustment to account for the later timing of puberty in historical populations and develop an alternative. We also test the validity of the age data, considering whether parents were more prone to lie about the ages of their daughters, and question whether the supply of girls was fundamentally different from that of boys. We conclude that neither proposition is justified. Disadvantage to girls remains, although its absence amongst younger children precludes an indictment of culturally founded gender bias. The height data must remain mute on the source of this discrimination but we utilise additional information to examine some hypotheses: occupational sorting, differential susceptibility to disease, poorer nutrition for girls, disproportionate stunting from the effects of nutritional deprivation, and type and amount of work undertaken. Of these we suggest that girls had to do arduous physical labour in the home alongside their factory work. The only (unsubstantiated) alternative is that girls were more likely than boys to be put into factory work below the legal age limit. Both represent forms of gender bias.     

Understanding the Influence of Race/Ethnicity,Gender, and Class on Inequalities in Academic and Non-Academic Outcomes among Eighth-Grade Students: Findings from an Intersectionality Approach

Socioeconomic, racial/ethnic, and gender inequalities in academic achievement have been widely reported in the US, but how these three axes of inequality intersect to determine academic and non-academic outcomes among school-aged children is not well understood. Using data from the US Early Childhood Longitudinal Study—Kindergarten (ECLS-K; N = 10,115), we apply an intersectionality approach to examine inequalities across eighth-grade outcomes at the intersection of six racial/ethnic and gender groups (Latino girls and boys, Black girls and boys, and White girls and boys) and four classes of socioeconomic advantage/disadvantage. Results of mixture models show large inequalities in socioemotional outcomes (internalizing behavior, locus of control, and self-concept) across classes of advantage/disadvantage. Within classes of advantage/disadvantage, racial/ethnic and gender inequalities are predominantly found in the most advantaged class, where Black boys and girls, and Latina girls, underperform White boys in academic assessments, but not in socioemotional outcomes. In these latter outcomes, Black boys and girls perform better than White boys. Latino boys show small differences as compared to White boys, mainly in science assessments. The contrasting outcomes between racial/ethnic and gender minorities in self-assessment and socioemotional outcomes, as compared to standardized assessments, highlight the detrimental effect that intersecting racial/ethnic and gender discrimination have in patterning academic outcomes that predict success in adult life. Interventions to eliminate achievement gaps cannot fully succeed as long as social stratification caused by gender and racial discrimination is not addressed.     

Social cognition and underlying cognitive mechanisms in children with an extra X chromosome: a comparison with autism spectrum disorder

Individuals with an extra X chromosome are at increased risk for autism symptoms. This study is the first to assess theory of mind and facial affect labeling in children with an extra X chromosome. Forty‐six children with an extra X chromosome (29 boys with Klinefelter syndrome and 17 girls with Trisomy X), 56 children with autism spectrum disorder (ASD) and 88 non‐clinical controls, aged 9–18 years, were included. Similar to children with ASD, children with an extra X chromosome showed significant impairments in social cognition. Regression analyses showed that different cognitive functions predicted social cognitive skills in the extra X and ASD groups. The social cognitive deficits were similar for boys and girls with an extra X chromosome, and not specific for a subgroup with high Autism Diagnostic Interview Revised autism scores. Thus, children with an extra X chromosome show social cognitive deficits, which may contribute to social dysfunction, not only in children showing a developmental pattern that is ‘typical’ for autism but also in those showing mild or late presenting autism symptoms. Our findings may also help explain variance in type of social deficit: children may show similar social difficulties, but these may arise as a consequence of different underlying information processing deficits.     

The influence of gender and somatotype on single-leg upright standing postural stability in children

The purpose of this study was to investigate the influence of gender and somatotypes on single-leg upright standing postural stability in children. A total of 709 healthy children from different schools were recruited to measure the anthropometric somatotypes and the mean radius of center of pressure (COP) on a force platform with their eyes open and eyes closed. The results were that (a) girls revealed significantly smaller mean radius of COP distribution than boys, both in the eyes open and eyes closed conditions, and (b) the mesomorphic, muscular children had significantly smaller mean radius of COP distribution than the endomorphic, fatty children and the ectomorphic, linear children during the eyes closed condition. The explanation for gender differences might be due to the larger body weight in boys. The explanation for somatotype differences might be due to the significantly lower body height and higher portion of muscular profile in the mesomorphic children.     

Race and gender differences in the relationships between anthropometrics and abdominal fat in youth

Objective: We examined the influence of race and gender on abdominal adipose tissue (AT) distribution for a given anthropometric measure including waist circumference (WC), waist‐to‐hip ratio (WHR) and waist‐to‐height (W/Ht) in youth. Methods and Procedures: Subjects included healthy 62 black and 98 white youth. A single transverse image of the abdomen (L4–L5) was obtained using computed tomography. Results: For a given BMI, there was a significant (P < 0.05) main effect of race and sex on the relationship between BMI and WC, such that boys and whites had a higher WC than girls and blacks. There was a significant (P < 0.05) main effect and interaction effect of gender on the relationship between WC and visceral AT, such that boys had a higher visceral AT than girls, and the difference was magnified with increasing WC. For a given WC, black boys and girls had higher abdominal subcutaneous AT (SAT) than white peers, wherein the magnitude of the difference is increased with increasing WC. For a given W/Ht, black boys had significantly (P < 0.05) lower visceral AT than white boys, but with no difference in girls. Black boys and girls had higher SAT than white peers, wherein the magnitude of the difference is increased with increasing W/Ht. Discussion: Our findings demonstrate a significant race and gender differential in the abdominal AT distribution for a given BMI, WC, WHR, and W/Ht. Future studies should take these differences into consideration when developing race‐ and gender‐specific anthropometric cut‐offs for obesity and obesity‐related health risks in youth.     

Prenatal hormones and childhood sex segregation: playmate and play style preferences in girls with congenital adrenal hyperplasia

We investigated playmate and play style preference in children with congenital adrenal hyperplasia (CAH) (26 females, 31 males) and their unaffected siblings (26 females, 17 males) using the Playmate and Play Style Preferences Structured Interview (PPPSI). Both unaffected boys and girls preferred same-sex playmates and sex-typical play styles. In the conflict condition where children chose between a same-sex playmate engaged in an other-sex activity or an other-sex playmate engaged in a same-sex activity, boys (both CAH and unaffected brothers) almost exclusively chose playmates based on the preferred play style of the playmate as opposed to the preferred gender label of the playmate. By contrast, unaffected girls used play style and gender label about equally when choosing playmates. Girls with CAH showed a pattern similar to that of boys: their playmate selections were more masculine than unaffected girls, they preferred a boy-typical play style and, in the conflict condition, chose playmates engaged in a masculine activity. These findings suggest that prenatal androgen exposure contributes to sex differences in playmate selection observed in typically developing children and that, among boys and girls exposed to high levels of androgens prenatally, play style preferences drive sex segregation in play.     

Estimating height from arm span measurement in Malawian children

Arm span and standing height were measured in 289 boys and 337 girls aged 6-15 years who were free from physical deformities which can affect stature or arm span. The arm span exceeded height in all age groups of boys and in older girls. At the age of 7, 11 and 12 years girls were significantly taller than the boys and had longer arm span while at the age of 15 years, the trend was opposite. The mean difference between the two anthropometric parameters for boys was 5.45 +/- 4.21 cm (t = 3.556, p < 0.001) and for girls was 4.94 +/- 4.96 cm (t = 3.542, p < 0.001). Correlation coefficient between height and arm span measurements for Malawian boys was 0.983 and for girls was 0.986. Height, arm span and height-arm span difference increased with age of children while height to arm span ratio decreased. The gender difference in height-arm span differences was only significant at the age of 15 years. Multiple regression and cross validation were performed. Height of Malawian children of both sexes can be estimated from equation: Height (cm) = 15.756 + (0.168 x age) + (0.839 x arm span) (SEE = 0.760, R2 = 0.988).     

Town and Gender Effects on Hair Lead Levels in Children from Three Sardinian Towns (Italy) with Different Environmental Backgrounds

This study reports hair lead (PbH) levels measured in 2002 in 193 children from three Sardinian towns: Carbonia, Gonnesa, and Sinnai. Carbonia and Gonnesa are in a polluted area of Sardinia due to their vicinity to the industrial zone of Portovesme. As a consequence of its economy and location, Sinnai is not exposed to lead pollution. PbH concentrations were determined by inductively coupled plasma atomic absorption spectrometry. The aim of this study was to evaluate if hair is a reliable biomarker to determine different degrees of exposure of populations to lead pollution and if there is a tendency to higher accumulation by males or females. The girls of Carbonia had the highest mean PbH value (2.21 microg/g), followed by the Gonnesa girls (2.03 microg/g), Carbonia boys (1.86 microg/g), Gonnesa boys (0.91 microg/g), and finally the Sinnai boys (0.68 microg/g) and girls (0.50 microg/g). Two-way analysis of covariance, with age as covariate, revealed a significant effect of town and sex on log PbH. Spearman's rank correlation coefficient indicated a significant positive concordance between PbH levels and gender (score for males=1, females=2). The results suggest that hair is a reliable biomarker to determine different levels of exposure of populations to lead pollution, and they indicate that females tend to accumulate lead in the hair more than males of the same age.