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Effect of lead levels in breast milk on the estimated infant daily intake of lead
S302
Abstracts / Toxicology Letters 196S (2010) S37–S351
The objective of this work was to determine the exposure condition in which metal uptake and toxic effects could be detected optimally. Two metals were studied: cadmium (as cadmium chloride) and silver (as silver nitrate and as colloidal nanosilver) and a set of experiments were carried out at various exposure times and starting at different stages of the embryos–larvae development. All experiments were carried out to a maximum length of 5 days post-fecundation in order to operate within the limits allowing the performance of an alternative toxicity test. No dechorionation was performed to maintain the status of the embryos as a natural as possible. At the end of the exposure, cadmium and silver were quantified in the embryos as well as in the exposure suspension by Atomic Absorbance Spectrometry. Lethal and sub-lethal effects were determined for all the exposure condition studied. Moreover, the expression of some toxicity biomarker genes was tested. The results obtained showed that higher levels of metal intake corresponded to a higher toxicity. The optimal exposure conditions where identified in experiments carried out on hatched larvae at 48 hpf or 72 hpf. doi:10.1016/j.toxlet.2010.03.953
P307-016 Oral cadmium exposure and placental steroidogenesis in rats ´ M. Piasek A. Mikolic, Institute for Medical Research and Occupational Health, Croatia Cadmium is a pervasive environmental pollutant. Contaminated food and water are the main sources of cadmium exposure. Gastrointestinal absorption of cadmium is up to 10% in adult human, up to 1% in laboratory rat, and the absorption increases 2–3 times during gestation. Cadmium accumulates in mammalian internal organs, including placenta, and interacts with most essential elements. Placental cadmium accretion can compromise placental functions including essential element transfer to the foetus and the synthesis of placental hormones. We evaluated effects of oral cadmium exposure during gestation on distribution of essential trace element in maternal and foetal tissues and on placental steroids in rats. Female rats (Wistar) with regular 4-day estrous cycles were randomly assigned to Cadmium group (exposed to 50 ppm Cd as chloride in demineralised drinking water; 5.83 ± 0.625 mg Cd/kg b.wt. a day from gestation day 1) and to Control (supplied with demineralised drinking water ad libitum). Experiment ended on gestation day 20, mother rats were anaesthetised, exsanguinated from abdominal aorta after blood sampling from the hart, and liver, kidney, placentas and foetuses dissected, weighed and prepared for element analysis (by atomic absorption spectrometry). Placentas were also used for steroid hormone assay (by enzyme-immunometric method). In Cadmium group, maternal body weights decreased, and organ, blood and foetal cadmium concentrations increased. Of essential trace elements, iron decreased in the maternal kidney, zinc decreased in placentas, and iron and zinc decreased in whole foetuses. Copper concentrations did not change. In Cadmium group, placental concentrations of progesterone increased and testosterone decreased. The results showed that cadmium accumulation in the placenta was associated with reduced transplacental transfer of iron and zinc from the mother rat to the foetuses and with placental steroid hormone disruption. All these could have unfavourable effects on foetal growth and development in utero and on postnatal organ and sexual development. doi:10.1016/j.toxlet.2010.03.954
P307-017 Age-related relationship between cadmium exposure and its renal adverse effect observed in female Japanese farmers exposed to cadmium through rice consumption H. Horiguchi 1 , E. Oguma 1 , S. Sasaki 2 , H. Okubo 2 , K. Murakami 2 , K. Miyamoto 1 , Y. Hosoi 1 , F. Kayama 1 1
Jichi Medical University, Japan, 2 Tokyo University, Japan
There are some cadmium (Cd)-contaminated areas in Japan, where farmers have been exposed to Cd through consumption of rice. We made a cross-sectional study on female farmers in those areas to investigate the renal adverse effect of Cd and establish the threshold of Cd nephropathy. After obtaining informed consents, we conducted group health examinations on female farmers at 20–70 s in two areas where rice with relatively high Cd contamination has often been detected (B: 659 subjects; C: 362), and one control in the same prefecture (A: 223). We collected peripheral blood and urine samples from the subjects, and measured the Cd concentrations as well as urinary alpha 1-microglobulin (MG) and beta 2-MG for indicators of renal tubular dysfunction. Urinary data were normalized by creatinine. At first, we stratified the subjects by age and compared the 3 areas. The highest blood and urinary Cd levels were observed in area C, especially at 70 s. On the other hand, urinary beta 2-MG levels at 60 s and 70 s in area C were significantly higher than those in area A. Next we mixed all data and stratified them by age and urinary Cd levels (<5 g/g cr., 5≤ and <10, 10≤). In subjects at lower than 70 years old, there were slow increases in urinary alpha 1- and beta 2-MG levels along with urinary Cd, but in subjects at 70 s, both urinary protein levels showed rapid increased at urinary Cd over 10 g/g cr. These results suggest that there would be two types of relationship between Cd exposure and its renal adverse effect; a slow dose–response relationship and a two-phase one with an inflection point at 10 g/g cr. of urinary Cd (i.e., threshold of Cd nephropathy), which is observed over 70 years old. doi:10.1016/j.toxlet.2010.03.955
P307-018 Effect of lead levels in breast milk on the estimated infant daily intake of lead M. Paoliello 1 , G. Koyashiki 1 , E. De Capitani 2 State University of Londrina, Brazil, 2 State University of Campinas, Brazil
1
Breast milk is the first food for infants and it serves as a major nutrient source for biological functions and growth during the early stages of life. However, maternal milk may sometimes contain chemical contaminants, which could have adverse effects on neonates or nursing infants. Women are chronically exposed to environmental lead since infancy, and they accumulate a significant bone lead burden into the child-bearing age. Maternal body burden and current exposure are major lead sources for the fetus, because lead can pass through the placenta. Mobilization of maternal bone lead into blood during lactation is favored by the increased bone turnover secondary to the increased calcium demand peculiar to this period. The contribution of lead in the breast milk, as the only dietary source, to the blood lead level of newborns was estimated to be in the range of 40–65%. The objective of this study was to establish the Hazard Index (HI) of the children’s exposure to lead through maternal milk. From January to July of 2007 milk lead
Abstracts / Toxicology Letters 196S (2010) S37–S351
levels of 92 usual milk donor women from the Bank of Milk of University Hospital of Londrina, State of Paraná, Brazil, were assessed. Although the concentrations of the metal founded in the milk were low (median equal to 3.0 g/L, varying from 1.0 to 8.0 g/L), the exposure of infants through the breast-feeding can be extended in time. The Hazard Index is the ratio between a parameter of exposure and the reference dose. A HI exceeding 1.0 indicates that infant consuming breast milk has a potential health risk. For the lead levels in the breast milk obtained in the present study, the HI ranged from 0.055 to 0.329. It means that the body burden of lead in the infants was not affected by the exclusive consume of breast milk. doi:10.1016/j.toxlet.2010.03.956
P307-019 Could selenium and omega-3 modify the oxidative damage promoted by methylmercury at low doses in rats? D. Grotto 1 , J.M. Serpeloni 1 , A.M. Moro 2 , M.F. Charão 2 , S.C. Garcia 2 , F. Barbosa Junior 1 1
Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Brazil, 2 Universidade Federal do Rio Grande do Sul, Brazil Methylmercury (MeHg) in one of the most malignant metals in the environmental and the main process responsible for its toxicity is the oxidative stress. It is recognized that diet and nutrition can modulate Hg toxicity. Thus, in the present study we have evaluated the possible protective effects of selenium (Se), and omega-3 on the oxidative damage caused by exposure to MeHg at low levels in rats. Animals were used according to the guidelines of the Committee on Care and Use of Experimental Animal Resources, University of São Paulo, Brazil (Process Approbation number: 07.1.1185.53.3). Animals were divided in 7 groups (6 rats/group)—I: Control; II: MeHg; III: Se; IV: Omega-3; V: MeHg + Se; VI: MeHg + Omega-3; VII: MeHg + Se + Omega-3. Rats were treated during 100 days and the doses were: MeHg 140 g/kg/day by gavage, Se 2 mg/L in drink water, Omega-3 dose supported by the recommended daily intake from the fabricant (two capsules three times a day for an adult individual, adapted for the rat weights) by gavage. Plasma MDA levels were quantified by high performance liquid chromatography, and blood GSH and plasma PC by spectrophotometric methods. Results were analyzed by Statistica 6.0 software. There was a significative increase in lipid peroxidation and a depletion in GSH levels in the MeHg exposed group compared to the controls. However, administration of selenium provided protective effects, restoring MDA and GSH concentrations. Respecting PC, none significant difference was found among the groups. In a different way, omega-3 administration was ineffective to alter MDA levels or GSH levels after MeHg exposure. Thus, our findings provide evidence of the oxidative property of MeHg, even at low doses, and the antioxidant capacity of Se. However, omega-3 did not show the same ability.Financial support: FAPESP. doi:10.1016/j.toxlet.2010.03.957
S303
P307-020 Additive effect of dl-penicillamine plus Prussian blue for the antidotal treatment of thallotoxicosis in rats A. Monroy 1 , C. Ríos 2 , S. Montes 2 1
Universidad Autonoma del Estado de Morelos, Mexico, 2 Instituto Nacional de Neurología y Neurocirugía, Mexico dl-Penicillamine (LD-P), given alone and in combination with Prussian blue (PB) was characterized in rats as treatments against acute thallium toxicity. Rats were intoxicated by intraperitoneal (ip) injection of thallium (I) acetate at dose 32 mg/kg (DL50 by rats). Later (24 h), pharmacological treatment was administered until day 5, as follows: PB 50 mg/kg, oral route, twice daily; LD-P 25 mg/kg ip route, twice daily. All animals were treated with ethical principles of National Institutes of Health of Mexico. Estimation Probability Survival was recorded during along experiment for each treatment. DL-P given alone not showed a significant survival. However, it in combination with PB increased significantly the survival (p < 0.05) with respect to control group. The Thallium levels were analyzed in blood, five organs and five brain regions after antidotal treatments. DL-P given alone decreased slightly thallium content in blood, body organs and brain regions. While its administration in combination with PB diminished significantly (p < 0.05) the thallium levels in the majority of tissues and brain regions studied. These thallium levels were lesser than PB group that diminished significantly (p < 0.05) metal content in most tissues. Results indicate in spite of DL-P administered alone no prevent significantly the mortality and metal accumulation in body tissues, its combination with PB could be considerate as an alternative antidotal treatment in the thallium toxicity due to this chelating agent given alone not redistribute thallium to the brain and in combination with PB has a pharmacological additive effect in acute thallotoxicosis. This work was partially supported by CONACYT project 985675. doi:10.1016/j.toxlet.2010.03.958
P307-021 Endogenous levels of tributyltin decreases GluR2 expression causing higher susceptibility to glutamate toxicity Y. Kotake, Y. Nakatsu, T. Takishita, S. Ohta Hiroshima University, Japan Tributyltin (TBT), an endocrine-disrupting chemical, has been used as a heat stabilizer, agricultural pesticide and component of antifouling paints. In this study, the influence of long-term exposure of TBT during neuronal development on glutamate receptors was investigated. Cortical neurons were exposed to 1–50 nM TBT for 9 days (from day 2 to day 10 in vitro). Long-term exposure of 1–20 nM TBT (endogenous levels) did not reduced number of neurons, but 50 nM TBT exposure to neurons did. Long-term exposure of 20 nM TBT affected mRNA expression of glutamate receptors. mRNA expression of NR1, NR2A, GluR1 and GluR2 was decreased, while that of GluR3 and GluR4 was increased. GluR2 protein was also reduced by long-term exposure of TBT. Because AMPA receptor lacking GluR2 has Ca2+ permeability, we investigated whether Ca2+ influx and toxicity was affected by glutamate. In the results, Ca2+ influx by glutamate was increased in TBT-treated neurons. Consistent with increase of Ca2+ influx, neurons became susceptibility to glutamate toxicity by long-term exposure of TBT and this susceptibility was abolished by a GluR2-lacking AMPA receptor antagonist. Thus, it is suggested that long-term exposure of endogenous levels
Abstracts / Toxicology Letters 196S (2010) S37–S351
The objective of this work was to determine the exposure condition in which metal uptake and toxic effects could be detected optimally. Two metals were studied: cadmium (as cadmium chloride) and silver (as silver nitrate and as colloidal nanosilver) and a set of experiments were carried out at various exposure times and starting at different stages of the embryos–larvae development. All experiments were carried out to a maximum length of 5 days post-fecundation in order to operate within the limits allowing the performance of an alternative toxicity test. No dechorionation was performed to maintain the status of the embryos as a natural as possible. At the end of the exposure, cadmium and silver were quantified in the embryos as well as in the exposure suspension by Atomic Absorbance Spectrometry. Lethal and sub-lethal effects were determined for all the exposure condition studied. Moreover, the expression of some toxicity biomarker genes was tested. The results obtained showed that higher levels of metal intake corresponded to a higher toxicity. The optimal exposure conditions where identified in experiments carried out on hatched larvae at 48 hpf or 72 hpf. doi:10.1016/j.toxlet.2010.03.953
P307-016 Oral cadmium exposure and placental steroidogenesis in rats ´ M. Piasek A. Mikolic, Institute for Medical Research and Occupational Health, Croatia Cadmium is a pervasive environmental pollutant. Contaminated food and water are the main sources of cadmium exposure. Gastrointestinal absorption of cadmium is up to 10% in adult human, up to 1% in laboratory rat, and the absorption increases 2–3 times during gestation. Cadmium accumulates in mammalian internal organs, including placenta, and interacts with most essential elements. Placental cadmium accretion can compromise placental functions including essential element transfer to the foetus and the synthesis of placental hormones. We evaluated effects of oral cadmium exposure during gestation on distribution of essential trace element in maternal and foetal tissues and on placental steroids in rats. Female rats (Wistar) with regular 4-day estrous cycles were randomly assigned to Cadmium group (exposed to 50 ppm Cd as chloride in demineralised drinking water; 5.83 ± 0.625 mg Cd/kg b.wt. a day from gestation day 1) and to Control (supplied with demineralised drinking water ad libitum). Experiment ended on gestation day 20, mother rats were anaesthetised, exsanguinated from abdominal aorta after blood sampling from the hart, and liver, kidney, placentas and foetuses dissected, weighed and prepared for element analysis (by atomic absorption spectrometry). Placentas were also used for steroid hormone assay (by enzyme-immunometric method). In Cadmium group, maternal body weights decreased, and organ, blood and foetal cadmium concentrations increased. Of essential trace elements, iron decreased in the maternal kidney, zinc decreased in placentas, and iron and zinc decreased in whole foetuses. Copper concentrations did not change. In Cadmium group, placental concentrations of progesterone increased and testosterone decreased. The results showed that cadmium accumulation in the placenta was associated with reduced transplacental transfer of iron and zinc from the mother rat to the foetuses and with placental steroid hormone disruption. All these could have unfavourable effects on foetal growth and development in utero and on postnatal organ and sexual development. doi:10.1016/j.toxlet.2010.03.954
P307-017 Age-related relationship between cadmium exposure and its renal adverse effect observed in female Japanese farmers exposed to cadmium through rice consumption H. Horiguchi 1 , E. Oguma 1 , S. Sasaki 2 , H. Okubo 2 , K. Murakami 2 , K. Miyamoto 1 , Y. Hosoi 1 , F. Kayama 1 1
Jichi Medical University, Japan, 2 Tokyo University, Japan
There are some cadmium (Cd)-contaminated areas in Japan, where farmers have been exposed to Cd through consumption of rice. We made a cross-sectional study on female farmers in those areas to investigate the renal adverse effect of Cd and establish the threshold of Cd nephropathy. After obtaining informed consents, we conducted group health examinations on female farmers at 20–70 s in two areas where rice with relatively high Cd contamination has often been detected (B: 659 subjects; C: 362), and one control in the same prefecture (A: 223). We collected peripheral blood and urine samples from the subjects, and measured the Cd concentrations as well as urinary alpha 1-microglobulin (MG) and beta 2-MG for indicators of renal tubular dysfunction. Urinary data were normalized by creatinine. At first, we stratified the subjects by age and compared the 3 areas. The highest blood and urinary Cd levels were observed in area C, especially at 70 s. On the other hand, urinary beta 2-MG levels at 60 s and 70 s in area C were significantly higher than those in area A. Next we mixed all data and stratified them by age and urinary Cd levels (<5 g/g cr., 5≤ and <10, 10≤). In subjects at lower than 70 years old, there were slow increases in urinary alpha 1- and beta 2-MG levels along with urinary Cd, but in subjects at 70 s, both urinary protein levels showed rapid increased at urinary Cd over 10 g/g cr. These results suggest that there would be two types of relationship between Cd exposure and its renal adverse effect; a slow dose–response relationship and a two-phase one with an inflection point at 10 g/g cr. of urinary Cd (i.e., threshold of Cd nephropathy), which is observed over 70 years old. doi:10.1016/j.toxlet.2010.03.955
P307-018 Effect of lead levels in breast milk on the estimated infant daily intake of lead M. Paoliello 1 , G. Koyashiki 1 , E. De Capitani 2 State University of Londrina, Brazil, 2 State University of Campinas, Brazil
1
Breast milk is the first food for infants and it serves as a major nutrient source for biological functions and growth during the early stages of life. However, maternal milk may sometimes contain chemical contaminants, which could have adverse effects on neonates or nursing infants. Women are chronically exposed to environmental lead since infancy, and they accumulate a significant bone lead burden into the child-bearing age. Maternal body burden and current exposure are major lead sources for the fetus, because lead can pass through the placenta. Mobilization of maternal bone lead into blood during lactation is favored by the increased bone turnover secondary to the increased calcium demand peculiar to this period. The contribution of lead in the breast milk, as the only dietary source, to the blood lead level of newborns was estimated to be in the range of 40–65%. The objective of this study was to establish the Hazard Index (HI) of the children’s exposure to lead through maternal milk. From January to July of 2007 milk lead
Abstracts / Toxicology Letters 196S (2010) S37–S351
levels of 92 usual milk donor women from the Bank of Milk of University Hospital of Londrina, State of Paraná, Brazil, were assessed. Although the concentrations of the metal founded in the milk were low (median equal to 3.0 g/L, varying from 1.0 to 8.0 g/L), the exposure of infants through the breast-feeding can be extended in time. The Hazard Index is the ratio between a parameter of exposure and the reference dose. A HI exceeding 1.0 indicates that infant consuming breast milk has a potential health risk. For the lead levels in the breast milk obtained in the present study, the HI ranged from 0.055 to 0.329. It means that the body burden of lead in the infants was not affected by the exclusive consume of breast milk. doi:10.1016/j.toxlet.2010.03.956
P307-019 Could selenium and omega-3 modify the oxidative damage promoted by methylmercury at low doses in rats? D. Grotto 1 , J.M. Serpeloni 1 , A.M. Moro 2 , M.F. Charão 2 , S.C. Garcia 2 , F. Barbosa Junior 1 1
Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Brazil, 2 Universidade Federal do Rio Grande do Sul, Brazil Methylmercury (MeHg) in one of the most malignant metals in the environmental and the main process responsible for its toxicity is the oxidative stress. It is recognized that diet and nutrition can modulate Hg toxicity. Thus, in the present study we have evaluated the possible protective effects of selenium (Se), and omega-3 on the oxidative damage caused by exposure to MeHg at low levels in rats. Animals were used according to the guidelines of the Committee on Care and Use of Experimental Animal Resources, University of São Paulo, Brazil (Process Approbation number: 07.1.1185.53.3). Animals were divided in 7 groups (6 rats/group)—I: Control; II: MeHg; III: Se; IV: Omega-3; V: MeHg + Se; VI: MeHg + Omega-3; VII: MeHg + Se + Omega-3. Rats were treated during 100 days and the doses were: MeHg 140 g/kg/day by gavage, Se 2 mg/L in drink water, Omega-3 dose supported by the recommended daily intake from the fabricant (two capsules three times a day for an adult individual, adapted for the rat weights) by gavage. Plasma MDA levels were quantified by high performance liquid chromatography, and blood GSH and plasma PC by spectrophotometric methods. Results were analyzed by Statistica 6.0 software. There was a significative increase in lipid peroxidation and a depletion in GSH levels in the MeHg exposed group compared to the controls. However, administration of selenium provided protective effects, restoring MDA and GSH concentrations. Respecting PC, none significant difference was found among the groups. In a different way, omega-3 administration was ineffective to alter MDA levels or GSH levels after MeHg exposure. Thus, our findings provide evidence of the oxidative property of MeHg, even at low doses, and the antioxidant capacity of Se. However, omega-3 did not show the same ability.Financial support: FAPESP. doi:10.1016/j.toxlet.2010.03.957
S303
P307-020 Additive effect of dl-penicillamine plus Prussian blue for the antidotal treatment of thallotoxicosis in rats A. Monroy 1 , C. Ríos 2 , S. Montes 2 1
Universidad Autonoma del Estado de Morelos, Mexico, 2 Instituto Nacional de Neurología y Neurocirugía, Mexico dl-Penicillamine (LD-P), given alone and in combination with Prussian blue (PB) was characterized in rats as treatments against acute thallium toxicity. Rats were intoxicated by intraperitoneal (ip) injection of thallium (I) acetate at dose 32 mg/kg (DL50 by rats). Later (24 h), pharmacological treatment was administered until day 5, as follows: PB 50 mg/kg, oral route, twice daily; LD-P 25 mg/kg ip route, twice daily. All animals were treated with ethical principles of National Institutes of Health of Mexico. Estimation Probability Survival was recorded during along experiment for each treatment. DL-P given alone not showed a significant survival. However, it in combination with PB increased significantly the survival (p < 0.05) with respect to control group. The Thallium levels were analyzed in blood, five organs and five brain regions after antidotal treatments. DL-P given alone decreased slightly thallium content in blood, body organs and brain regions. While its administration in combination with PB diminished significantly (p < 0.05) the thallium levels in the majority of tissues and brain regions studied. These thallium levels were lesser than PB group that diminished significantly (p < 0.05) metal content in most tissues. Results indicate in spite of DL-P administered alone no prevent significantly the mortality and metal accumulation in body tissues, its combination with PB could be considerate as an alternative antidotal treatment in the thallium toxicity due to this chelating agent given alone not redistribute thallium to the brain and in combination with PB has a pharmacological additive effect in acute thallotoxicosis. This work was partially supported by CONACYT project 985675. doi:10.1016/j.toxlet.2010.03.958
P307-021 Endogenous levels of tributyltin decreases GluR2 expression causing higher susceptibility to glutamate toxicity Y. Kotake, Y. Nakatsu, T. Takishita, S. Ohta Hiroshima University, Japan Tributyltin (TBT), an endocrine-disrupting chemical, has been used as a heat stabilizer, agricultural pesticide and component of antifouling paints. In this study, the influence of long-term exposure of TBT during neuronal development on glutamate receptors was investigated. Cortical neurons were exposed to 1–50 nM TBT for 9 days (from day 2 to day 10 in vitro). Long-term exposure of 1–20 nM TBT (endogenous levels) did not reduced number of neurons, but 50 nM TBT exposure to neurons did. Long-term exposure of 20 nM TBT affected mRNA expression of glutamate receptors. mRNA expression of NR1, NR2A, GluR1 and GluR2 was decreased, while that of GluR3 and GluR4 was increased. GluR2 protein was also reduced by long-term exposure of TBT. Because AMPA receptor lacking GluR2 has Ca2+ permeability, we investigated whether Ca2+ influx and toxicity was affected by glutamate. In the results, Ca2+ influx by glutamate was increased in TBT-treated neurons. Consistent with increase of Ca2+ influx, neurons became susceptibility to glutamate toxicity by long-term exposure of TBT and this susceptibility was abolished by a GluR2-lacking AMPA receptor antagonist. Thus, it is suggested that long-term exposure of endogenous levels