Measurements of radiation exposure of dentistry students during their radiological training using thermoluminescent dosimetry.

Exposure among dentistry students has not been assessed or regulated in Mexico. This work assessed the average exposure of 35 dentistry students during their training with the aid of LiF:Mg,Cu,P+PTFE thermoluminescent dosimeters. For the students in the roles of dentist and observers, maximum accumulated equivalent dose obtained was 2.59±0.11 and 4.64±0.39 mSv, respectively. Students in the role as patients received a maximum accumulated effective dose of 28.41±0.31 mSv. If compared to occupational dose limits, this latter value is 56% of the recommended value of 50 mSv in any year. It was found that in all cases, values of equivalent dose to the women breasts were equal to the background dose. Results are discussed and compared to previous published work. Suggested recommendations were given to authorities in order to minimize exposure of the students in the role as patients.

Defectos del tubo neural y de labio y paladar hendido: un estudio morfológico / Neural tube defects, cleft lip and palate: a morphological study

El objetivo del trabajo fue realizar una evaluación morfológica externa de recién nacidos (RN) y lactantes con diagnóstico de defectos de tubo neural (DTN) y labio hendido c/s paladar hendido (LH c/s PH) para determinar el tipo de defecto, ubicación, extensión, clasificación y evaluar la proporción de RN con retardo del crecimiento intauterino (RCIU) y lactantes desnutridos. Estudio descriptivo. Se estudiaron 36 niños desde su nacimiento hasta los 12 meses de edad; 20 con DTN y 16 con LH c/s PH. El estudio se realizó en cinco hospitales de la ciudad de Chihuahua, México. Se hizo una evaluación morfológica externa y antropometría de los niños. Los DTN se clasificaron como lesiones abiertas y cerradas, como defectos altos o bajos, según el modelo de sitios múltiples y por la CIE-10. Los LH c/s PH se clasificaron como unilaterales o bilaterales, completos e incompletos y como aislados o múltiples. Se determinó RCIU en los RN y desnutrición en los lactantes. El análisis estadístico se realizó con el paquete STATA 8.0 para Windows. Se estudiaron 20 casos de DTN; 3 lactantes y 17 RN. De LH c/s PH fueron 8 lactantes y 8 RN. En cuanto a los DTN, 60 por ciento fueron mielomeningocele y correspondían a lesiones abiertas. El 85 por ciento se localizaron a nivel alto. En el modelo de cierres múltiples, el Z1 fue el 80 por ciento. Los LH c/s PH más frecuentes fueron aquellos con hendidura completa (50 por ciento). El 35 por ciento de los RN con DTN tuvieron RCIU y el 67 por ciento de los lactantes presentaron desnutrición. Es importante conocer los mecanismos del desarrollo de las anomalías congénitas ya que esto permite precisar el momento en que ocurrió la falla y permite estudiar los factores predisponentes, con lo cual se puede ofrecer asesoramiento genético para una posible prevención.

The objective of this study was to perform an external morphological evaluation of newborn (NB) and lactating children (LC) with diagnosis of neural tube defects (NTD) and cleft lip c/s palate (CL/s PH) to determine the type of defect, location, extent, classification and assess the proportion of infants with intrauterine growth retardation (IUGR) and malnourished infants. A descriptive study in 36 children from birth to 12 months of age , 20 with NTD and 16 with LH c / s PH was carried out. The study was conducted in five hospitals in the city of Chihuahua, Mexico. An external morphological assessment and anthropometry of children were performed. The DTN lesions were classified as open and closed, as defects high or low, depending on the model of multiple sites and ICD-10. The LH c / s PH were classified as unilateral or bilateral, complete or incomplete, and as isolated or multiple. IUGR was determined in the RN and malnutrition in infants. A statistic analysis was made with STATA 8.0 for Windows. We studied 20 cases of NTDs, 3 LCs and 17 RN. LH c/s PH were 8 LC and 8 RN. The DTN, 60 percent were myelomeningocele and corresponded to open lesions. Eighty five percent were located at high level. In the model of multiple closures, the Z1 was 80 percent. The LH c/s PH were more frequent with complete cleft (50 percent). The 35 percent of newborns with NTD had IUGR and 67 percent of LC had malnutrition. It is important to understand the mechanisms of development of congenital anomalies as this allows to specify the time the fault occurred and to study the underlying diseases to offer genetic counseling for possible prevention.

Altered expressions of MMP-2, MMP-9, and TIMP-2 in placentas from women exposed to lead.

Experimental studies have shown that prenatal exposure to lead (Pb) produces morphological changes related to extracellular matrix remodelling. To analyse whether the matrix metalloproteinases (MMPs), particularly MMP-2, MMP-9, and the tissue inhibitor of metalloproteinases-2 (TIMP-2), are associated with morphological alterations found in placentas, the expression of these enzymes was evaluated by immunohistochemical and image analyses in placentas of women with histories of environmental exposure to Pb. The median maternal concentration of Pb in blood was 4.68 µg/dL (x = 5.85 ± 6.48 µg/dL). Significant differences related to the exposure to Pb were not detected in newborn or placenta weight. MMP-2, MMP-9, and TIMP-2 were expressed in the syncytiotrophoblast layer of placental villi. A significant increase in both MMP-2 and MMP-9 was observed in placentas of women with concentrations of Pb in blood ≥4.68 µg/dL (p = 0.01 and 0.03 for MMP-2 and MMP-9, respectively) and decrease in TIMP-2 expression (p = 0.01) resulted in a significant increase in MMP-2/TIMP-2 ratio (p < 0.01). Increased expression of MMPs may be induced to aid in repairing placental tissue damaged by the exposure to Pb and that TIMP-2 decreases its expression to permit tissue repair. Increased expression of MMPs may be important to consider as a mechanism for generating placental abnormalities and in the induction of preterm delivery or abortion.

Mother-fetus transference of lead and cadmium in rats: involvement of metallothionein.

This study was designed to assess the effect of Cadmium (Cd) and lead (Pb) exposure during pregnancy in rats and their correlation with metallothionein (MT). Rats were exposed to either 10 ppm Cd or 300 ppm Pb through drinking water during pregnancy. Both metals were measured in placenta, fetus brain and fetal and maternal blood. MT was quantified in placenta and fetus brain and it was also observed in placenta by immunohistochemical technique. Offspring weight was found to be significantly lower for the Cd exposure group than for the control group. A Cd increase in the placenta of the exposed group was accompanied by MT induction; these effects were related to a limited accumulation of Cd in fetus brain. In contrast, dam Pb exposure caused an accumulation of Pb in the fetus brain and induced damage to placenta. The results account for differences in the transference of these metals during pregnancy that could be related to their toxicity.

Relación entre los niveles de ácido fólico, vitamina B12 y homocisteína materna y los defectos de tubo neural y labio hendido / Relation between levels of folic acid, vitamin B12 and maternal homocysteine with neural tube defects and cleft lip

El objetivo del trabajo fue determinar la asociación entre los niveles de ácido fólico, vitamina B (Vit B12) y homocisteína (Hci) maternos, con defectos del tubo neural (DTN) y labio hendido (LH) con y sin paladar hendido (c/s PH). Se realizó un estudio tipo casos y controles. Casos, con diagnóstico de DTN y LH c/s PH (n=36) y cuatro controles hospitalarios por caso (n=141). Se incluyeron recién nacidos (RN) y lactantes hasta 12 meses de edad. Las variables de pareamiento fueron: edad del RN o lactante, etnia y hospital. Un 23 por ciento de etnia Tarahumara y 77 por ciento mestizos. Se determinó ácido fólico intraeritrocitario (AFI), plasmático (AFP) y Vit B12 por radioinmunoensayo, la Hci por inmunoensayo de fluorescencia polarizada. Se consideró deficiencia si el AFI fue <160 ng/mL, AFP <3.5 ng/ mL y la Vit B12 <200 pg/mL e hiperhomocisteinemia, si Hci >15 J.mol/L. El análisis estadístico se realizó a través de regresión logística condicionada. Se identificó deficiencia de AFI en el 22 por ciento de las mujeres cuyos recién nacidos o lactantes presentaron algún tipo de defecto congénito y en el 12 por ciento de los controles. La relación entre AFI y DTN, LH c/s PH ajustada por edad materna, exposición a plaguicidas y zona de residencia fue RM 2,96 (IC 95 por ciento 0,92-9,46). No se encontraron diferencias en los niveles de Hci ni de Vit B12. Conclusiones: Nuestros resultados sugieren que RN cuyas madres cursan con una deficiencia de AFI tienen mayor riesgo de presentar DTN y LH c/s PH.

Objective: To determine the association between maternal folate deficiency, neural tube defects (NTDs), and cleft lip, with and without cleft palate (CL/P). Material and methods: A case/control study was conducted. The cases included subjects with diagnoses of NTD and CL/P (n=36) and four hospital controls per case (n=141); the study included newborns (NBs) and nursing babies up to 12monthsof age. The parameter variables were the following: the age of the NB or nursing baby, the ethnic group, and the hospital of origin. The Tarahumara ethnic group made up 23 percent of the cases, while 77 percent were mestizos. The red cell folate (RCF), the plasma folie acid (PFA), and the vitamin B12 levels were determined by radioimmunoassay and the homocysteine levels by polarized fluorescence immunoassay. A deficiency was considered to be present if the RCF were <160 ng/mL, the PFA <3.5 ng/mL and the vitamin B <200 pg/ mL; hyperhomocysteinemia was defined as HC >15 J,mol/L. The statistical analysis was carried out through of conditional logistic regression. Results: An RCF deficiency was identified in 22 percent of the women whose newborn or nursing babies presented with some type of congenital defect and in 12 percent of the controls. The correlation adjusted by maternal age, exposure to pesticides and zone of residence was OR 2.96 (CI 95 percent 0.92-9.46). There was no difference in vitamin B12 or homocysteine levels between groups. Conclusions: Our results suggest that newborns whose mothers present with an RCF deficiency have an increased risk of displaying NTD and CL/P.

Non-cancer health effects of pesticides: systematic review and implications for family doctors.

OBJECTIVE: To investigate whether there are associations between exposure to pesticides and 4 chronic non-cancer health effects: dermatologic, neurologic, reproductive, and genotoxic effects. DATA SOURCES: We searched PreMedline, MEDLINE, and LILACS using the key word pesticide combined with the term for the specific health effect being searched. Reviewers scanned the references of all articles for additional relevant studies. STUDY SELECTION: Studies since 1992 were assessed using structured inclusion and quality-of-methods criteria. Studies scoring <4 on a 7-point global methodologic quality scale were excluded. In total, 124 studies were included. These studies had a mean quality score of 4.88 out of 7. SYNTHESIS: Strong evidence of association with pesticide exposure was found for all neurologic outcomes, genotoxicity, and 4 of 6 reproductive effects: birth defects, fetal death, altered growth, and other outcomes. Exposure to pesticides generally doubled the level of genetic damage as measured by chromosome aberrations in lymphocytes. Only a few high-quality studies focused on the dermatologic effects of pesticides. In some of these studies, rates of dermatitis were higher among those who had had high exposure to pesticides on the job. CONCLUSION: Evidence from research on humans consistently points to positive associations between pesticide exposure and 3 of the 4 non-cancer health outcomes studied. Physicians have a dual role in educating individual patients about the risks of exposure and in reducing exposure in the community by advocating for restrictions on use of pesticides.

Relation between birth weight and placenta weight.

With the goal to establish a model that relates birth weight to placenta weight, adjusted for the most documented predictors of birth weight, 300 live newborns were studied, all were products of single gestation. Inclusion criteria were newborns with gestational age of 37 weeks or older according to the date of last menstruation, whose mothers did not have diabetes mellitus, high blood pressure, pre-eclampsia, or eclampsia. The weight of the newborn was identified from the anthropometry data collected by previously trained nursing personnel in each of the participating hospitals. Immediately after delivery, the placenta was weighed. Multiple linear regression was used to see the effect of placenta weight and each variable on birth weight. The mean of birth weight was 3,369 g with a standard deviation (SD) of 445 g. Placenta weight had a mean of 537 g (SD: 96 g). The relation between the weight of the placenta and the birth weight was significant, and we found that for each gram increase in placenta weight, birth weight is increased by 1.98 g (SE = 0.25, p < 0.01) and this relation is not linear, since the quadratic term is significant. Placenta weight has a nonlinear relation to the birth weight and is an important predictor of birth weight. Together with the gestational age and the maternal age and size, it explains 32% of the variability of birth weight. Placenta weight can be a 'sentinel' indicator of nutritional and/or environmental problems.

Effect of maternal lead burden on infant weight and weight gain at one month of age among breastfed infants.

INTRODUCTION: Transfer of lead from bone to the bloodstream increases during lactation. However, the effect of maternal lead burden on growth in breastfed newborns is still unknown. This study examined early postnatal growth in a cohort of healthy breastfed newborns in relation to maternal bone lead burden. METHODS: Lead levels were measured among 329 mother-infant pairs in umbilical cord blood at birth and in maternal and infant venous blood at 1 month postpartum. Maternal evaluations at 1 month postpartum included lead measures in blood and bone (measured in the tibia and the patella). Blood lead was determined by graphite furnace atomic absorption spectrophotometry. Bone lead was measured by (109)Cd Kx-radiograph fluorescence instrument. The primary endpoints were attained weight 1 month of age, and weight gain from birth to 1 month of age, which were analyzed in relation to lead biomarkers and relevant covariates by linear regression models. RESULTS: Infants studied had an average weight gain of 33.1 g/day (standard deviation [SD] = 11.6). Mean infant (at 1 month of age) and maternal blood lead levels were 5.6 microg/dL (SD = 3.0) and 9.7 microg/dL (SD = 4.1), respectively. Mean maternal bone lead levels were 10.1 microg of lead/g (SD = 10.3) and 15.29 microg of lead/g (SD = 15.2) of bone mineral for tibia and patella, respectively. Infant blood lead levels were inversely associated with weight gain, with an estimated decline of 15.1 g per microg/dL of blood lead. Children who were exclusively breastfed had significantly higher weight gains; however, this gain decreased significantly with increasing levels of patella lead. The multivariate regression analysis predicted a 3.6-g decrease in weight at 1 month of age per microg of lead per gram bone mineral increase in maternal patella lead levels. CONCLUSIONS: Maternal lead burden is negatively associated to infant attained weight at 1 month of age and to postnatal weight gain from birth to 1 month of age. Additional studies are needed to better understand this source of exposure and to develop interventions to minimize its impact.

Predictors of blood lead levels in agricultural villages practicing wastewater irrigation in Central Mexico.

To investigate whether the agricultural use of untreated wastewater (i.e. crop irrigation) was associated with elevated blood lead levels in a farming population in the Mezquital Valley and which risk factors, other than exposure to untreated wastewater, were associated with elevated blood lead levels, lead levels were measured in venous blood obtained from 735 individuals. Blood samples were analyzed by atomic absorption spectrophotometry. Food habits and dietary intake were gathered by interview, using a semi-quantitative food-frequency questionnaire. The average blood lead level was 7.8 microg/dL (SD 4.66 microg/dL; range 1.2-36.7 microg/dL). 23% of the study population had blood lead levels exceeding 10 microg/dL. The use of lead-glazed ceramics (LGC) was significantly associated with elevated lead levels (p = < 0.001). Other significant variables included age, gender (males), and non-farming-related occupations (e.g., technicians, factory workers). p = 0.005, 0.08, and 0.001, respectively. When the analysis was stratified by the use of LGC for food preparation, an inverse relationship between higher daily calcium intake and blood lead level was detected (beta = - 0.040, p = < 0.05). Thus, blood lead levels were positively associated with the use of LGC. Calcium intake showed a protective effect, maybe by decreasing absorption of lead in the gastrointestinal tract. No association between occupational exposure to untreated wastewater or crop consumption and blood lead levels was detected. Further environmental and health surveillance is recommended.

Determinants of bone and blood lead concentrations in the early postpartum period.

OBJECTIVE: This study investigated determinants of bone and blood lead concentrations in 430 lactating Mexican women during the early postpartum period and the contribution of bone lead to blood lead. METHODS: Maternal venous lead was measured at delivery and postpartum, and bone lead concentrations, measured with in vivo K-x ray fluorescence, were measured post partum. Data on environmental exposure, demographic characteristics, and maternal factors related to exposure to lead were collected by questionnaire. Linear regression was used to examine the relations between bone and blood lead, demographics, and environmental exposure variables. RESULTS: Mean (SD) blood, tibial, and patellar lead concentrations were 9.5 (4.5) microg/dl, 10.2 (10.1) microg Pb/g bone mineral, and 15.2 (15.1) microg Pb/g bone mineral respectively. These values are considerably higher than values for women in the United States. Older age, the cumulative use of lead glazed pottery, and higher proportion of life spent in Mexico City were powerful predictors of higher bone lead concentrations. Use of lead glazed ceramics to cook food in the past week and increased patellar lead concentrations were significant predictors of increased blood lead. Patellar lead concentrations explained one third of the variance accounted for by the final blood lead model. Women in the 90th percentile for patella lead had an untransformed predicted mean blood lead concentration 3.6 microg/dl higher than those in the 10th percentile. CONCLUSIONS: This study identified the use of lead glazed ceramics as a major source of cumulative exposure to lead, as reflected by bone lead concentrations, as well as current exposure, reflected by blood lead, in Mexico. A higher proportion of life spent in Mexico City, a proxy for exposure to leaded gasoline emissions, was identified as the other major source of cumulative lead exposure. The influence of bone lead on blood lead coupled with the long half life of lead in bone has implications for other populations and suggests that bone stores may pose a threat to women of reproductive age long after exposure has declined.

[Relationship between pregestational body mass index and body composition in the immediate puerperium]. / Relación entre el índice de masa corporal pregestacional y la composición corporal en el puerperio inmediato.

To determine the correlation between pregestational body mass index and certain body composition parameters measured by bioelectric impedance (percentage of fat weight, fat mass, and lean weight) and to compare the body composition of women in immediate puerperal period with non-pregnant women, a cross sectional study was done including 86 women in physiologic puerperal period and 90 healthy non-pregnant women, from the Instituto Mexicano del Seguro Social, in Chihuahua, Mexico, aged 16 to 40 years old. The variables considered were the body mass index (BMI) before pregnancy, percentage of fat, fat mass, lean weight, total water and bio-resistance. Body composition was measured by bioelectric impedance (BIO) from 4 to 12 hours after delivery. Correlation coefFicient for BMI and percentage of fat was r = 0.66 (p < 0.01), and for BMI and fat mass, it was r = 0.74 (p < 0.01). In non-pregnant women the total water was 35.5 +/- 5 L and in women in the immediate puerperal period 38.5 +/- 5 L (p < 0.01). In conclusion, BMI before pregnancy is a suitable predictor for body composition in the puerperal period. However, it does not discriminate important variables such as total body water, so it may be convenient to use BIA for surveillance of body composition during pregnancy.

Blood lead levels and calcium intake in Mexico City children under five years of age.

OBJECTIVE: The relationship between daily calcium intake and blood lead levels was evaluated among children under five years of age living in Mexico City. METHODS: A random sample of 200 children under five years of age, resident in two neighborhoods of Mexico City was selected: Xalostoc, an industrial neighborhood, and Tlalpan, a residential neighborhood (100 from each area). The mothers of these children filled out a questionnaire on predictors of blood lead levels including daily calcium intake. Lead levels were determined from the venous blood samples. Calcium intake was assessed using a short Food Frequency Questionnaire including 11 food items that accounted for 95% of calcium intake in Mexico. RESULTS: The average blood lead level was 9.93 microg dl(-1) (range 1-31 microg dl(-1)). An inverse relationship was observed between blood lead levels and daily calcium intake. This relationship was statistically significant among children aged 13 months-5 years. CONCLUSION: The results suggest that calcium provided a protective effect against lead accumulation in the body among children. Further studies should be undertaken to evaluate this hypothesis through experimental design.

[Accumulation of lead in bone and its effects on health]. / Acumulación de plomo en hueso y sus efectos en la salud.

The adverse effects of lead have been known for long since the metal affects practically all organs and systems of the human body. Recently, toxic effects have been reported in the cardiovascular and nervous systems at lead levels previously considered to be secure. The main lead storage site in the body is bone. The toxicologic significance of this fact has been clarified only recently. The present study analyzes the role of lead as an endogenous source of exposure, as a chronic exposure biomarker and as a target organ. Recent advances to measure bone lead through fluorescent X-Rays are discussed. Additionally, the importance of bone lead from a public health perspective in places with a chronic history of exposure such as Mexico City, and in some occupational environments is reviewed with particular attention placed on reproductive age women, who are potential lead sources for the fetus and lactating infant.

The influence of bone and blood lead on plasma lead levels in environmentally exposed adults.

There is concern that previously accumulated bone lead stores may constitute an internal source of exposure, particularly during periods of increased bone mineral loss (e.g., pregnancy, lactation, and menopause). Furthermore, the contribution of lead mobilized from bone to plasma may not be adequately reflected by whole-blood lead levels. This possibility is especially alarming because plasma is the main circulatory compartment of lead that is available to cross cell membranes and deposit in soft tissues. We studied 26 residents of Mexico City who had no history of occupational lead exposure. Two samples of venous blood were collected from each individual. One sample was analyzed by inductively coupled plasma-magnetic sector mass spectrometry for whole-blood lead levels. The other sample was centrifuged to separate plasma, which was then isolated and analyzed for lead content by the same analytical technique. Bone lead levels in the tibia and patella were determined with a spot-source 109Cd K-X-ray fluorescence instrument. Mean lead concentrations were 0.54 microg/l in plasma, 119 microg/l in whole blood, and 23.27 and 11.71 microg/g bone mineral in the patella and tibia, respectively. The plasma-to-whole-blood lead concentration ratios ranged from 0.27% to 0.70%. Whole-blood lead level was highly correlated with plasma lead level and accounted for 95% of the variability of plasma lead concentrations. Patella and tibia lead levels were also highly correlated with plasma lead levels. The bivariate regression coefficients of patella and tibia on plasma lead were 0.034 (p<0. 001) and 0.053 (p<0.001), respectively. In a multivariate regression model of plasma lead levels that included whole-blood lead, patella lead level remained an independent predictor of plasma lead level (ss = 0.007, p<0.001). Our data suggest that although whole-blood lead levels are highly correlated with plasma lead levels, lead levels in bone (particularly trabecular bone) exert an additional independent influence on plasma lead levels. It will be important to determine whether the degree of this influence increases during times of heightened bone turnover (e.g., pregnancy and lactation).

[Length and weight at birth: the role of maternal nutrition]. / Longitud y peso al nacer: el papel de la nutrición materna.

OBJECTIVE: To identify determinants of weight (BW) and length at birth (BL). MATERIAL AND METHODS: We studied 481 mother-newborn pairs in three Mexico City hospitals. Multiple regression models were developed to identify statistically significant predictors of BW and BL with respect to a predetermined biological model. Independent variables included were: maternal anthropometry, age, smoking habits, and civil status, parental education, obstetric history, hypertension, and neonatal characteristics. RESULTS: In the group with calf circumference (CC), height and head circumference below the median BW was 133, 92 and 96 g lower (+/- 35 standard error -SE-, p < 0.01) than the group above the median, adjusting for socioeconomic, obstetric history, and neonatal characteristics (NC). In the group below the median CC or height, BL was 5.8 or 6.2 mm (+/- 1.9 mm SE, p < 0.01) respectively, adjusting for obstetric history and NC. CONCLUSIONS: Results suggest that maternal anthropometry is the most important predictor of birth size and that predictors for BW and BL differ.

Decrease in birth weight in relation to maternal bone-lead burden.

OBJECTIVES: Birth weight predicts infant survival, growth, and development. Previous research suggests that low levels of fetal lead exposure, as estimated by umbilical cord blood-lead levels at birth, may have an adverse effect on birth weight. This report examines the relationship of lead levels in cord blood and maternal bone to birth weight. METHODS: Umbilical cord and maternal venous blood samples and anthropometric and sociodemographic data were obtained at delivery and 1-month postpartum. Blood-lead levels were analyzed by atomic absorption spectrophotometry. Maternal tibia and patella lead levels were determined at 1-month postpartum with use of a spot-source 109Cd K-X-ray fluorescence instrument. The relationship between birth weight and lead burden was evaluated by multiple regression with control of known determinants of size at birth. RESULTS: Data on all variables of interest were obtained for 272 mother-infant pairs. After adjustment for other determinants of birth weight, tibia lead was the only lead biomarker clearly related to birth weight. The decline in birth weight associated to increments in tibia lead was nonlinear and accelerated at the highest tibia lead quartile. In the upper quartile, neonates were on average, 156 grams lighter than those in the lowest quartile. Other significant birth weight predictors included maternal nutritional status, parity, education, gestational age, and smoking during pregnancy. CONCLUSIONS: Our results indicate that bone-lead burden is inversely related to birth weight. Taken together with other research indicating that lead can mobilize from bone into plasma without detectable changes in whole blood lead, these findings suggest that bone lead might be a better biomarker than blood lead. Because lead remains in bone for years to decades, mobilization of bone lead during pregnancy may pose a significant fetal exposure with health consequences, long after maternal external lead exposure has declined.

Higher milk intake during pregnancy is associated with lower maternal and umbilical cord lead levels in postpartum women.

Lead exposure and its deleterious effects continue to be a problem in many countries. The lack of effective and safe treatments for low-level intoxication has promoted environmental interventions to control different sources of lead. In this study we evaluated the effect of milk consumption in 1849 mother-and-child pairs participating in the lead surveillance program in Mexico City. The mean lead levels were 11.2 micrograms/dL for maternal blood lead (MBL) and 10.8 micrograms/dL in umbilical cord. The correlation between blood lead and umbilical cord lead was r = 0.74. Forty-eight percent of the MBL exceeded 10 micrograms/dL and 9.5% exceeded 20 micrograms/dL. Maternal blood lead was positively related to the use of lead-glazed ceramic were and to traffic exposure and was inversely related to the consumption of milk and orange juice. Women who reported the consumption of more than 7 glasses of milk per week had a blood lead level of 8.7 micrograms/dL; in comparison, those women who reported a consumption of less than 7 glasses per week had a blood lead level of 11.1 micrograms/dL. Similar findings were observed for lead measured in umbilical cord. The association between lead levels and milk intake remained unchanged after taking in consideration other predictors of blood lead. This study suggests that a simple intervention could reduce lead burden among women and their newborns.