Dose-response relationship between blood lead levels and hematological parameters in children from central China.

BACKGROUND: Lead is a heavy metal that can affect the human hematological system. However, reports are limited on the dose-response relationship between blood lead levels (BLLs) and hematological parameters in children. This study aimed to explore the dose-response relationship between BLLs and hematological measurements among children in China. METHODS: A cross-sectional design was used. A total of 743 children aged 5-8 years were recruited from two counties in central China. The BLLs and blood levels of iron, zinc, and calcium were determined, and hematological parameters were measured. RESULTS: All hematological measurements and BLLs were logarithm-transformed to ensure a normal distribution. The geometric mean of the BLLs of all children was 82.4 µg/L. Forty-one percent of the children had BLLs ≥ 100 µg/L. The lead-poisoning percentages of the children were significantly associated with gender, age, district of residence, and environmental lead exposure level. Multivariate linear regression analyses showed no significant linear correlation between BLL and each hematological parameter among the children with BLLs ≥ 100 µg/L. The analyses also revealed a small increase in red blood cell count (RBC) with increasing BLLs in the BLLs < 100 µg/L group (ß = 0.03, P =  0.048). A negative association was noted between BLLs and blood platelet (PLT) count in the children with BLLs < 100 µg/L (ß = -0.90, P < 0.001). Logistic regression analyses showed that BLLs were significantly associated with decreased hemoglobin (Hb) levels, RBC counts, PLT counts and mean corpuscular hemoglobin (MCH) after adjusting for potential confounders. Such analyses also revealed a dose-response relationship between the BLLs and hematological parameters (Hb level, RBC count, and PLT count). The children with BLLs ≥ 100 µg/L were 2.72, 2.51, and 3.76 times more likely to achieve decreased RBC counts, Hb levels and PLT counts, respectively, compared to those with BLLs < 100 µg/L. Compared with children with BLLs < 100 µg/L, those with BLLs ≥ 100 µg/L were 3.16 and 4.38 times more likely to show decreased Hb levels and PLT counts respectively in the high-level lead-exposure group and 4.33 times more likely to achieve a decreased PLT count in the low-level lead-exposure group. The individuals with BLLs of the highest quartile were 3.65, 5.87, and 29.23 times more likely to exhibit decreased Hb levels, RBC counts, and PLT counts, respectively, than the children with BLLs of the lowest quartile. CONCLUSION: Our findings suggested a negative association between BLLs and hematological indicators (Hb level, RBC count, PLT count and MCH). A strong negative, non-linear dose-response relationship was also showed between BLLs and hematological parameters (Hb level, RBC count, and PLT count).

Association of Bone Turnover Levels with MTHFR Gene Polymorphisms among Pregnant Women in Wuhan, China.

Pregnancy is a critical stimulator of bone mineral resorption. We used to find the MTHFR gene polymorphisms are related with blood lead levels among pregnant women. Pregnancy-stimulated bone turnover may be associated with MTHFR gene polymorphisms too. In this article, we aimed to determine the relationship between MTHFR gene polymorphisms and bone turnover rates among the pregnant women. The participants including pregnant and non-pregnant women were selected and recruited during their routine prenatal or physical examination from July to October in 2012. A total of 1000 participants, including 250 pregnant women in the first, second, and third trimesters and 250 non-pregnant women, were enrolled in the study. Finally, after excluding 27 participants unable to provide blood samples, 973 eligible participants (i.e., 234,249, and 248 pregnant women in the first, second, and third trimesters, respectively, and 242 non-pregnant women) were included in the research. The MTHFR gene 1298CC homozygote carriers were more susceptible to yield higher plasma homocysteine levels than the 1298AA/AC carriers, with standardized coefficients of 0.086 (P<0.05) and 0.104 (P<0.01) of all the participants and the pregnant women, respectively. The MTHFR gene 1793AA homozygote carriers more likely showed higher plasma osteocalcin levels (standardized ß=0.091,P<0.01) than the 1793GG/GA carriers among all the subjects. Plasma homocysteine levels were positively correlated with blood lead levels among the participants and the pregnant women with standardized coefficients of 0.320 (P<0.01) and 0.179 (P<0.01), respectively. Plasma osteocalcin levels were positively associated with blood lead levels among pregnant and non-pregnant women with standardized coefficients of 0.084 (P<0.05) and 0.125 (P<0.01), respectively. In conclusion, homocysteine and osteocalcin contents in plasma are associated with the MTHFR gene A1298C polymorphism and blood lead levels among pregnant women. The MTHFR gene A1298C polymorphism-related homocysteine is a possible risk factor for increased blood lead levels among Chinese women.

Benchmark dose estimation for cadmium-induced renal tubular damage among environmental cadmium-exposed women aged 35-54 years in two counties of China.

BACKGROUND: A number of factors, including gender, age, smoking habits, and occupational exposure, affect the levels of urinary cadmium. Few studies have considered these influences when calculating the benchmark dose (BMD) of cadmium. In the present study, we aimed to calculate BMDs and their 95% lower confidence bounds (BMDLs) for cadmium-induced renal tubular effects in an age-specific population in south-central China. METHODS: In this study, urinary cadmium, ß2-microglobulin, and N-acetyl-ß-D-glucosaminidase levels were measured in morning urine samples from 490 randomly selected non-smoking women aged 35-54 years. Participants were selected using stratified cluster sampling in two counties (counties A and B) in China. Multiple regression and logistic regression analyses were used to investigate the dose-response relationship between urinary cadmium levels and tubular effects. BMDs/BMDLs corresponding to an additional risk (benchmark response) of 5% and 10% were calculated with assumed cut-off values of the 84th and 90th percentile of urinary ß2-microglobulin and N-acetyl-ß-D-glucosaminidase levels of the controls. RESULTS: Urinary levels of ß2-microglobulin and N-acetyl-ß-D-glucosaminidase increased significantly with increasing levels of urinary cadmium. Age was not associated with urinary cadmium levels, possibly because of the narrow age range included in this study. Based on urinary ß2-microglobulin and N-acetyl-ß-D-glucosaminidase, BMDs and BMDLs of urinary cadmium ranged from 2.08 to 3.80 (1.41-2.18) µg/g cr for subjects in county A and from 0.99 to 3.34 (0.74-1.91) µg/g cr for those in county B. The predetermined benchmark response of 0.05 and the 90th percentiles of urinary ß2-microglobulin and N-acetyl-ß-D-glucosaminidase levels of the subjects not exposed to cadmium (i.e., the control group) served as cut-off values. CONCLUSIONS: The obtained BMDs of urinary cadmium were similar to the reference point of 1 µg/g cr, as suggested by the European Food Safety Authority, indicating that cadmium exposure must be reduced to protect human health.

Application of BMD approach to identify thresholds of cadmium-induced renal effect among 35 to 55 year-old women in two cadmium polluted counties in China.

BACKGROUND: Cadmium (Cd) is a heavy metal that can cause renal tubular dysfunction in humans. Women are among the high-risk group for Cd health effects. Determining the thresholds of Cd-induced renal effects is important. Thus, in this article, we aimed to identify the benchmark dose (BMD) and its low limit (BMDL) levels as the Cd thresholds for Chinese women. METHODS: Epidemiologic investigation was performed in county A and county B to obtain data on Cd exposure and its renal effect on respondents. Levels of Cd (UCd), ß2-microglobulin (UB2M), and N-acetyl-ß-D-glucosaminidase (UNAG) were measured in morning urine samples. The BMD approach was mainly performed. RESULTS: Results of the BMD approach were similar whether the method was conducted for the two sets of data (collected in CA and CB, respectively) separately or cooperatively. The BMD/BMDL values of UCd for all subjects were 1.07/0.44 and 2.12/0.53 µg/g cr based on UB2M and UNAG, respectively, given a predetermined BMR of 0.05. CONCLUSIONS: The presented thresholds of Cd-induced renal effects (i.e., the BMDLs of UCd) are close to the counterpart values reported in Japan, Sweden and Belgium.

delta-Aminolevulinic acid dehydratase activity, urinary delta-aminolevulinic acid concentration and zinc protoporphyrin level among people with low level of lead exposure.

To evaluate the relationship of delta-aminolevulinic acid dehydratase (ALAD) activity, urinary delta-aminolevulinic acid (ALAU) level and blood zinc protoporphyrin (ZPP) concentration to low blood lead (PbB) levels, these biomarkers were determined for all subjects enrolled from a rural area of southeast China where people had low levels of exposure to lead. The mean values of PbB, ALAD, ALAU and ZPP were 67.11 microg/L (SD: 1.654, range: 10.90-514.04), 339.66 nmol ml(-1)h(-1) (1.419, 78.33-793.13), 20.64 microg/L (1.603, 2.00-326.00), and 0.14 micromol/L (3.437, 0.01-2.26), respectively. ALAD was inversely associated with low levels of PbB. ZPP was inversely related to low levels of PbB but positively related to relatively higher levels of PbB. Alcohol drinking contributed to low ALAD in men. Women had higher ZPP than men. ALAU had no significant association with PbB. In conclusion, ALAD possibly has a non-linear relation with low to moderate levels of PbB. At moderate levels of PbB, ZPP increases with increasing levels of PbB. ALAU is not suitable as an indicator for low levels of lead exposure.

[Logistic analysis on risk factors related to smear positive pulmonary tuberculosis].

OBJECTIVE: To explore the risk factors on relapsing tuberculosis related to smear positive pulmonary tuberculosis which had been cured for five years. METHODS: Patients with smear positive pulmonary tuberculosis registered in 1995 from ten countries in Hubei province were studied and logistic regression was used for data analysis. RESULTS: The 5-year relapse rate of smear positive pulmonary tuberculosis was 3.85 percent. Risk factors related to relapse would include being non-modeled county, negative smear after treated for three months, the class of retreatment, management of non-DOTS, method of chemotherapy and patients that did not get treated by the tuberculosis institute, with odds ratios of 0.15, 4.62, 3.68, 5.88 and 6.47, respectively. CONCLUSION: Effect standard, regulation DOTS and the centralized management measure might have had effects on decreasing the relapse rate.