Blood selenium concentration in a selected population of children inhabiting industrial regions in Upper Silesia (Poland)

Impact of Lead Exposure on Thyroid Status and IQ Performance among School-age Children Living Nearby a Lead-Zinc Mine in China

BACKGROUND

Lead exposure is one of the most concerning public health problems worldwide, particularly among children. Yet the impact of chronic lead exposure on the thyroid status and related intelligence quotient performance among school-age children remained elusive.

OBJECTIVE

The aim of this study was to evaluate the influence of lead exposure on the thyroid hormones, amino acid neurotransmitters balances, and intelligence quotient (IQ) among school-age children living nearby a lead-zinc mining site. Other factors such as rice lead levels, mothers' smoking behavior, and diet intake were also investigated.

METHODS

A total of 255 children aged 7-12 years old were recruited in this study. Blood lead level (BLL), thyroid hormones including free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH), and amino acid neurotransmitters such as glutamate (Glu), glutamine (Gln), and γ-aminobutyric acid (GABA) were measured using graphite furnace atomic absorption spectroscopy (GFAAS), chemiluminescence immunoassay, high performance liquid chromatography (HPLC). Raven's standard progressive matrices (SPM) and the questionnaire were used to determine IQ and collect related influence factors.

RESULTS

The average BLL of children was 84.8 μg/L. The occurrence of lead intoxication (defined as the BLL ≥ 100 μg/L) was 31.8%. Serum TSH levels and IQ of lead-intoxicated children were significantly lower than those without lead toxicity. The GABA level of girls with the lead intoxication was higher than those with no lead-exposed group. Correlation analyses revealed that BLL were inversely associated with the serum TSH levels (R= -0.186, p < 0.05), but positively related with IQ grades (R = 0.147, p < 0.05). Moreover, BLL and Glu were inversely correlated with IQ. In addition, this study revealed four factors that may contribute to the incidence of lead intoxication among children, including the frequency of mother smoking (OR = 3.587, p < 0.05) and drinking un-boiled stagnant tap water (OR = 3.716, p < 0.05); eating fresh fruits and vegetables (OR = 0.323, p < 0.05) and soy products regularly (OR = 0.181, p < 0.05) may protect against lead intoxication.

CONCLUSION

Lead exposure affects the serum TSH, GABA levels and IQ of school-aged children. Developing good living habits, improving environment, increasing the intake of high-quality protein and fresh vegetable and fruit may improve the condition of lead intoxication.

Interaction between blood selenium concentration and a levels of oxidative stress and antioxidative capacity in healthy children

The study aimed at defining the relationship between blood selenium concentration (Se-B) and levels of oxidative stress and antioxidative capacity in healthy children. The studies were conducted on 337 children (mean age: 8.53±1.92 years). The groups of individuals with Se-B <1st quartile (group I, Se-B<70μg/L), with Se-B fitting the range of 1st quartile and median (group II, Se-B: 70-76.9μg/L), with Se-B between the median and 3rd quartile (group III, Se-B: 77-83.9μg/L) and those with Se-B above the 3rd quartile (group IV, Se-B≥84μg/L) were distinguished. Level of oxidative stress was defined using determination of urine malonyldialdehyde concentration (MDA) and urine 8-hydroxy-2-deoxyguanosine concentration (8-OHdg). Urine total antioxidant status (TAS) was determined. In group IV TAS was significantly higher than in groups I-III. A positive correlation was detected between Se-B and TAS. In healthy children an appropriately high Se-B seems to ensure higher total antioxidative status.