Neurotoxicity and Biomarkers of Lead Exposure: a Review

Appropriate selection and measurement of lead biomarkers of exposure are critically important for health care management purposes,public health decision making,and primary prevention synthesis.Lead is one of the neurotoxicants that seems to be involved in the etiology of psychologies.Biomarkers are generally classified into three groups:biomarkers of exposure,effect,and susceptibility.The main body compartments that store lead are the blood,soft tissues,and bone;the half-life of lead in these tissues is measured in weeks for blood,months for soft tissues,and years for bone.Within the brain,lead-induced damage in the prefrontal cerebral cortex,hippocampus,and cerebellum can lead to a variety of neurological disorders,such as brain damage,mental retardation,behavioral problems,nerve damage,and possibly Alzheimer’s disease,Parkinson’s disease,and schizophrenia.This paper presents an overview of biomarkers of lead exposure and discusses the neurotoxic effects of lead with regard to children and adults.

Breast Milk Lead and Cadmium Levels in Suburban Areas of Nanjing,China

Objective To evaluate levels of lead(Pb) and cadmium(Cd) in the breast milk in the second postpartum month,to investigate the relationship between Pb/Cd levels in breast milk and some sociodemographic parameters,and to explore whether these levels affect the infants' physical status or the mothers' psychological status(postpartum depression).Methods A cross-sectional study was conducted between November 2009 and December 2010.Altogether 170 healthy mothers were enrolled from Nanjing Maternity and Child Health Care Hospital.The inclusion criteria were:voluntary to participate in this study,healthy,with no chronic disease,breastfeeding in the second postpartum month,living in a suburban but not non-industrial area of Nanjing,and not occupationally exposed to toxic metals.All the mothers completed a questionnaire and were evaluated based on the Edinburgh Postpartum Depression Scale(EPDS) to identify the risk of postpartum depression.Pb and Cd levels in breast milk were determined by inductively coupled plasma mass spectroscopy.The infants of these mothers were examined for their z scores of weight for age,length for age,head circumference for age,and body mass index for age.Results The median breast milk levels of Pb and Cd were 40.6 μg/L and 0.67 μg/L,respectively.In 164(96.5%) of the 170 samples,Pb levels were higher than the limit reported by the World Health Organization(> 5 μg/L).Breast milk Cd level was > 1 μg/L in 54(31.8%) mothers.The mothers with a history of anemia had a higher breast milk Pb level than those without a history of anemia(41.1 μg/L vs.37.9 μg/L,P = 0.050).The median breast milk Cd level in those who were active and passive smokers during pregnancy was significantly higher than that in non-smokers(0.88 μg/L vs.0.00 μg/L,P = 0.025).The breast milk Cd level in the mothers not taking iron and vitamin supplements for 2 months postpartum was higher than in those taking the supplements(iron supplement:0.74 μg/L vs.0.00 μg/L,P = 0.025;vitamin supplement:0.78 μg/L vs.0.00 μg/L,P = 0.005).Breast milk Cd level at the second postpartum month was negatively correlated with the z scores of head circumference(r = 0.248,P = 0.042) and weight for age at birth(r = 0.241,P = 0.024) in girls.No correlation was found between the breast milk Pb/Cd levels and the EPDS scores.Conclusion Considering the high levels of Pb and Cd in breast milk in this study,breast milk monitoring programs are necessary.

Primary Screening for Breast Diseases among 17618 Women in Wufeng Area, a Region with High Incidence of Cervical Cancer in China

In this study, the current status for breast diseases in a region with high-incidence of cervical cancer were epidemiologically investigated. From March to August, 2009, 17618 women, from Wufeng area of Hubei province, China, were recruited to screen breast diseases by using breast infrared diagnostic apparatus. Other diagnostic methods, such as B-mode ultrasound, X-ray mammography, needle biopsy and pathological examination were, if necessary, used to further confirm the diagnosis. The screening showed that 5990 of 17618 cases (34.00%) had breast diseases, 5843 (33.16%) had mammary gland hyperplasia, 48 (0.27%) had breast fibroadenoma, 11 (0.06%) had breast carcinoma, and 88 (0.50%) had other breast diseases. The peak morbidity of breast cancer was found in the women aged 50–60 ages. The morbidity of breast cancer was significantly increased in women elder than or equal to 50 years old (n=8, 0.157%) in comparison with that in the subjects younger than 50 years old (n=3, 0.024%) (u=2.327, P<0.05). It was shown that the occurrence of breast diseases was concentrated in women aged 20–40 years, while the total morbidity reached its peak at the age of 30 years and then decreased sharply after age of 40. Compared with the patients elder than or equal to 40 years old (n=3289, 27.46%), the morbidity rate of breast diseases was significantly increased in women less than 40 years old (2648 cases, 47.18%; P<0.001). However, there was no significant difference in the morbidity of breast diseases between the age group of 20–29 years and that of 30–39 years (P=0.453), and both of them were high. There was no significant association between the morbidity of breast diseases and cervical cancer. Since the morbidity of breast diseases was higher among young women, more attention should be paid to the screening of breast diseases among young women for early diagnosis.

Priming effects in Chinese character recognition for Chinese children with developmental dyslexia

BACKGROUND： Dyslexic children exhibit reading ability unmatched to age, although they possess normal intelligence and are well educated. OBJECTIVE： To examine the performance of dyslexic children in Chinese characters visual recognition tasks and to investigate the relationship between priming effect in character recognition and dyslexia. DESIGN, TIME AND SETTING： A case-control study was performed at the Department of Children and Adolescent Health and Maternal Care, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology between March and June 2007. PARTICIPANTS： A total of 75 primary school students in grades 3 and 5 were selected from two primary schools in Wuhan City, Hubei province, China, and were assigned to three groups. （1） Reading disability （RD, n = 25）; （2） chronological age （CA） group （n = 25 normal readers that were intelligence quotient and age-matched to the RD group）; （3） reading level （RL） group （n = 25 normal readers that were intelligence quotient and RL-matched to the RD group）. All children were right-handed and had normal or corrected-to-normal vision. METHODS： Recognition of target characters was performed in each child using a masked prime paradigm. Recognition speed and accuracy of graphic, phonological, and semantic characters were examined. Simultaneously, data, with respect to response time for each target character and error rate, were recorded to calculate facilitation values （unrelated RT-related RT）. MAIN OUTCOME MEASURES： Response time, facilitation, and error rate in Chinese character recognition task were calculated. RESULTS： The baseline-adjusted facilitation of graphic, phonological, and semantic priming for dyslexic children was -0.010, -0.010, and 0.001, respectively. Dyslexic children displayed inhibition in graphic and phonological prime conditions. Facilitations under the three prime conditions were 0.026, 0.026, and 0.022 for the CA group. In the RL group, results were 0.062, 0.058, and 0.031 respectively. The differences of baseline-adjusted facilitation across the three groups were significant [F （2, 216） = 17.91, P 〈 0.01 ], whereas the main effect of prime condition IF （2, 216） = 0.49, P 〉 0.05] and the interaction of group x prime condition [F （4, 216） = 0.91, P 〉 0.05] were not significant. The error rate under the three prime conditions was 0.066, 0.077, and 0.079 for the RD group. As for the CA group, the results were 0.057, 0.071, and 0.074 accordingly, and in the RL group, the results were 0.119, 0.111, and 0.121, respectively. The difference of error rate across the three groups was significant （F = 6.61, P = 0.002）. The error rate was significantly greater in the RL group, compared with the CA and RD groups, while no significant difference existed between the RD and CA groups. CONCLUSION： Dyslexic children were slower to recognize target characters than normal readers, and did not exhibit significant prime effects in graphic and phonological primer condition. These results suggested that dyslexic children exhibited general deficits in phonological and graphic processing, and presented a different pattern in character recognition. These results could be interpreted by parallel-distributed processing models.

Towards prenatal biomonitoring in Nanjing, China： lead and cadmium levels in the duration of pregnancy

Background Prenatal lead and cadmium exposure will not only influence the mother＇s organ systems,but also will provide an environment that may influence the fetus and neonate in a harmful way.In the present study,we detected the blood lead levels （BLLS） and cadmium levels for the duration of pregnancy and 6-12 weeks after delivery and to analyze the influencing factors of BLLs in healthy pregnant women.Methods A cohort study survey was carried out.We recruited 174 healthy pregnant women without pregnancy or obstetric complications or abnormal pregnancy outcomes as the gravida group,and 120 healthy non-pregnant women as the control group.Results The lead concentrations in the three pregnancy trimesters and in the postpartum period were：（5.98±2.43）,（5.54±2.01）,（5.59±1.97）,and （6.76±1.74） μg/dl; and （6.75±2.13） μg/dl in the control group.The cadmium concentrations in the three pregnancy trimesters and postpartum period were 1.61±0.45,1.63±0.46,1.64±0.49,and 1.67±0.57.We found that the BLLs in the gravida group were lower than in the control group during all three trimesters.Occupations,supplement nutritional elements （dietary supplements and nutritional （food） elements）,and the time of house painting could affect BLLs in pregnant women.Lead-related occupations,using cosmetics,and living in a house painted more recently than one year previously are risk factors of high BLLs among pregnant women,while calcium,iron,zinc,and milk supplements are protective factors.Conclusions These findings may help people,especially pregnant women,to reduce lead exposure via supplements of calcium,iron,zinc,and milk or avoiding contacting risk factors.

Endoplasmic reticulum stress-induced apoptosis in the development of reproduction

Proteins synthesized in the endoplasmic reticulum （ER） are properly folded with the assistance of ER chaperones. Accumulation of misfolded protein in the ER triggers an adaptive ER stress （ERS） response termed the unfolded protein response. Recent interest has focused on the possibility that the accumulation of misfolded proteins can also contribute to reproductive response, including preimplantation embryos, testicular germ cell, placenta, and unexplained intrauterine growth restriction （IUGR）. The major ERS pathway constituents are present at all stages of preimplantation development and that the activation of ERS pathways can be induced at the 8-cell, morula and blastocyst stage. This review mainly introduced the research progress of ERS induced apoptosis of reproductive cells, providing a new direction for the research of reproductive disease therapy.