Eleuterio Umpierrez | University of the Republic (UdelaR). Faculty of Chemistry (original) (raw)

Papers by Eleuterio Umpierrez

Forensic science review, 2015

Aim: We investigated the impact of vibrating acoustic airflow, the high frequency (f ≥ 100 Hz) an... more Aim: We investigated the impact of vibrating acoustic airflow, the high frequency (f ≥ 100 Hz) and the low frequency (f ≤ 45 Hz) sound waves, on the enhancement of intrasinus drug deposition. Methods: 81m Kr-gas ventilation study was performed in a plastinated human cast with and without the addition of vibrating acoustic airflow. Similarly, intrasinus drug deposition in a nasal replica using gentamicin as a marker was studied with and without the superposition of different modes of acoustic airflow. Results: Ventilation experiments demonstrate that no sinus ventilation was observed without acoustic airflow although sinus ventilation occurred whatever the modes of acoustic airflow applied. Intrasinus drug deposition experiments showed that the high frequency acoustic airflow led to 4-fold increase in gentamicin deposition into the left maxillary sinus and to 2fold deposition increase into the right maxillary sinus. Besides, the low frequency acoustic airflow demonstrated a significant increase of 4-fold and 2-fold in the right and left maxillary sinuses respectively. Conclusion: We demonstrated the benefit of different modes of vibrating acoustic airflow for maxillary sinus ventilation and intrasinus drug deposition. The degree of gentamicin deposition varies as a function of frequency of the vibrating acoustic airflow and the geometry of the ostia.

Forensic science review, 2015

Aim: We investigated the impact of vibrating acoustic airflow, the high frequency (f ≥ 100 Hz) an... more Aim: We investigated the impact of vibrating acoustic airflow, the high frequency (f ≥ 100 Hz) and the low frequency (f ≤ 45 Hz) sound waves, on the enhancement of intrasinus drug deposition. Methods: 81m Kr-gas ventilation study was performed in a plastinated human cast with and without the addition of vibrating acoustic airflow. Similarly, intrasinus drug deposition in a nasal replica using gentamicin as a marker was studied with and without the superposition of different modes of acoustic airflow. Results: Ventilation experiments demonstrate that no sinus ventilation was observed without acoustic airflow although sinus ventilation occurred whatever the modes of acoustic airflow applied. Intrasinus drug deposition experiments showed that the high frequency acoustic airflow led to 4-fold increase in gentamicin deposition into the left maxillary sinus and to 2fold deposition increase into the right maxillary sinus. Besides, the low frequency acoustic airflow demonstrated a significant increase of 4-fold and 2-fold in the right and left maxillary sinuses respectively. Conclusion: We demonstrated the benefit of different modes of vibrating acoustic airflow for maxillary sinus ventilation and intrasinus drug deposition. The degree of gentamicin deposition varies as a function of frequency of the vibrating acoustic airflow and the geometry of the ostia.

Summary: Introduction: marijuana is most highly consumed abuse substance in America and Europe af... more Summary: Introduction: marijuana is most highly consumed abuse substance in America and Europe after alcohol. In Uruguay, the prevalence is close to 23%. The active ingredient, delta 9-tetrahydrocannabinol, is responsible for its psychoactive effects. The main source of access for a child involves a relative and/or neighbor. Intoxication may be more severe in children, In 2013,.cannabis-sale regulating Act 19.172 was approved in Uruguay, and it generated a new potentially risky scenario for children. Objective: report clinical cases of severe unintentional intoxication from cannabis between March and June 2017, and analyze circumstances that led to exposure, clinical manifestations, severity and evolution. Clinical observation: 4 children (9 months, 1, 2 and 8 years of age) were assisted. In all cases, they had ingested cannabis in their home environment. They presented severe neurological symptoms: depressed level of consciousness, convulsive seizures, dystonia, ataxia, irritability. They required supportive measures, digestive decontamination and additional laboratory tests. Urine screening was positive in 4 cases. In 2, we performed confirmatory technique. As per the Poisoning Severity Score, all children suffered moderate intoxication. They were assisted jointly by a clinical toxicologist. Conclusions: children showing predominantly acute neurological symptoms with no apparent cause can be the subject of severe cannabis intoxication, especially when cannabis consumption takes place in their household environments. Surveillance is needed and future research will certainly contribute to the creation of prevention strategies with the purpose of reducing the potential unwanted consequences of this new scenario for children. Key words: Cannabis; Poisoning; Neurotoxicity syndromes; Marijuana use; Consciousness disorders

Anfamed, Dec 23, 2014

The consumption of alcohol and cocaine can affect pregnant’s health, fetus´s health and child dev... more The consumption of alcohol and cocaine can affect pregnant’s health, fetus´s health and child development, so it is important to recognize fetal exposure to these substances in order to plan appropriatemonitoring and timely interventions. The aim of the study was to determine the frequency of alcohol consumption and cocaine intake in the Hospital Pereira Rossell’s (Montevideo, Uruguay) population.The investigation consisted on an observational analytic cross-sectional study of 240 puerperal women and their children born at the Hospital Pereira Rossell from November 2010 to March 2011. The method used for the identification of free fatty acid ethyl esters in meconium of newborns was developed at the Polo Tecnologico de Pando, Facultad de Quimica, Universidad de la Republica for this investigation. The media of maternal age was 25; Alcohol consumption during pregnancy was admitted by 81 women, and the presence of free fatty acids ethyl esters was confirmed in 113 cases (49.78%); the consumption of cocaine hydrochloride and freebase cocaine was positive in 9.25% cases. Alcohol consumption was identified in half of pregnant women. The consumption of cocaine derivatives in the population studied was high. Exposed fetus can be identified with the analysis of meconium samples, with more certainty than by reports of patients.

Arch. pediatr. …, 2010

Título: Consumo de pasta base de cocaína en Uruguay en el embarazo, su incidencia, característica... more Título: Consumo de pasta base de cocaína en Uruguay en el embarazo, su incidencia, características y repercusiones/Cocaine base paste consumption during pregnancy in Uruguay, its incidence, characteristics and repercussions

Summary Cocaine base paste, CBP (the acronym in Spanish for "pasta base de cocaína") co... more Summary Cocaine base paste, CBP (the acronym in Spanish for "pasta base de cocaína") consumption is a major health and social problem in several Latin- American countries, including Uruguay. Currently, there are no published scientific evidences of CBP central actions that may explain the syntomatology observed in its consumers. CBP is a cocaine-smoking form. Although subjective effects induced by CBP

Environmental Monitoring and Assessment, 2014

The objective of this study was to predict chloroform formation resulting from the process of dis... more The objective of this study was to predict chloroform formation resulting from the process of disinfecting water, particularly trihalomethane which is most frequently produced. A statistical model was used which included repeated measurements of water parameters used for monitoring water quality at 51 sites covering the municipal water system of Montevideo. Samples were taken considering different seasons from June 2009 to July 2011 in Montevideo. Total samples (n= 330) were analytically studied using the headspace-gas chromatography method coupled with mass spectrometry. Chloroform was the dependent variable and the covariables were pH, temperature, free chlorine, and total chlorine. A Tobit analysis with an unstructured correlation matrix was performed, and a significant interaction was found between pH and free chlorine for the prediction of chloroform formation. We concluded that parameters for the continuous control of water quality for consumption can be used to predict the levels of chloroform that may be present. Given the large measurement to variability found in the repeated measurements, the use of averages that include more than one season is not recommended to determine the degree of compliance with acceptable levels established by norms.

Presentado a : IUNS 20th International Congress of Nutrition. Granada, Espana. 15-20 setiembre 2013

Pharmacology Biochemistry and Behavior

Pharmacology Biochemistry and Behavior

Revista chilena de pediatría, Jun 1, 2017

Introduction: Post partum depresion (DPP) is the most frequent psquiatric disorder in pregnant wo... more Introduction: Post partum depresion (DPP) is the most frequent psquiatric disorder in pregnant woman and it may affect the neurodevelopment of their offspring. Our goal was to analyze the association between maternal depressive symptoms at 6 months after birth and child's neurodevelopmental disorders at 18 months-old, in a homogeneous population characterized by low socioeconomic and cultural level. Patients and Methods: A prospective cohort study was conducted. There were included 127 healthy postpartum women and their infants. A structured interview was performed, which included patronymic data and family perception before discharge. Binomial monitoring took place at 6 months postpartum, when was applied the Beck test for depression and anxiety to mothers; children´s neurodevelopment at 18 month-old was evaluated by Lezine Revised Brunettest. Results: The sample consisted of 125 women and their children. The mean age was 24.5 year old (SD 6.02); 30.6 % had completed less than 6 years of formal education. The incidence of moderate to severe postpartum depression at 6 months after birth was 20%. The overall development score mean was 73.52 (SD 8.06) in the depression population and 76.97 (SD 8.07) in the population without depression (p = 0.04). The development coefficient was 69.08 (SD: 10.35) in the depression population and 74.11 (SD 0.67) in the population without depression (p = 0.01). Conclusions: The incidence of moderate to severe DPP was 20%. Persistent DPP in a vulnerable socioeconomic context has impact on child development.

Cogent Environmental Science, Aug 31, 2018

The use of chlorine to disinfect water produces a series of by-products, particularly trihalometh... more The use of chlorine to disinfect water produces a series of by-products, particularly trihalomethanes. This is important given that there is a recognized association with different types of cancer after prolonged exposure, as well as with probable adverse effects on reproduction, especially in relation to offspring. The concentrations of these organic compounds vary greatly depending on the season and the conditions involved in providing water for consumption. This study was aimed at determining the geographic distribution pattern of chloroform in the city of Montevideo, and correlating that with the characteristics of the water distribution network. A total of 400 samples were taken from a sampling network between 2009 and 2015. Chloroform was identified by analyzing these samples using the headspace gas chromatography/mass spectrometry method. Data regarding piping length, diameter, and type of material were obtained. A geographic information system was constructed and hot spots were analyzed using the Getis-Ord G i * statistic. A neighborhood piping density index was also proposed. The analysis found two zones in the city: hot and cold spots. The proposed index showed an increase in the G i * statistic as the neighborhoods' piping density increased, with a strong correlation. In addition, the highest G i * statistic values corresponded to

Journal Fur Praktische Chemie, Aug 1, 1999

Archivos De Pediatria Del Uruguay, Mar 1, 2014

Introducción: el consumo de cafeína es un hábito extendido a nivel mundial, destacándose el mate ... more Introducción: el consumo de cafeína es un hábito extendido a nivel mundial, destacándose el mate en los países del cono sur como una fuente importante de ingesta. Objetivos: valorar la ingesta de cafeína en el embarazo, el aporte de las diferentes fuentes de ingesta y su relación con el peso al nacer. Metodología y población: se realizó un estudio observacional, analítico de corte transversal que incluyó 240 puérperas y sus recién nacidos sanos de 35 semanas de gestación o mayores. Resultados: la media de edad materna fue de 24,96 (DE=6,01), Estaban casadas o convivían con su pareja 179 mujeres (74,58%). De ellas 67 (28,03%) eran primigestas. La media de controles del embarazo fue 7,31 (DE=3,32) y nacieron por cesárea 70 (29,17%). Las características de los recién nacidos reflejan los criterios de inclusión referidos: 35 semanas de gestación o mayores, vigorosos, internados junto a su madre luego del nacimiento. Durante todo el embarazo la fuente principal de cafeína fue la ingesta de mate. La media de consumo de cafeína fue de 273,99 mg/día; el consumo de mate es la principal fuente de cafeína con una media de 240 mg/día, aportando un 85% de la ingesta diaria de cafeína. Se observó consumo de cafeína mayor de 300 mg/día en 77 embarazadas, 32% de la muestra. La ingesta de cafeína mayor a 300 mg/día se asocia al nacimiento de un niño pequeño para la edad gestacional, la ingesta de 100 mg de cafeína por día disminuye el peso al nacer en 38 g, independientemente del índice de masa corporal y el hábito de fumar. Conclusiones: el consumo de cafeína es elevado en las embarazadas en Uruguay, superando los 300 mg diarios en 32% de la muestra. La ingesta de mate es la fuente principal de cafeína en esta población. El consumo de cafeína mayor a 300 mg diarios se asocia a mayor riesgo de recién nacidos pequeños para la edad gestacional. En vistas a la evidencia científica actual debería implementarse una adecuada información para lograr un descenso del consumo de mate y cafeína durante la gestación.

Forensic science review, 2015

Aim: We investigated the impact of vibrating acoustic airflow, the high frequency (f ≥ 100 Hz) an... more Aim: We investigated the impact of vibrating acoustic airflow, the high frequency (f ≥ 100 Hz) and the low frequency (f ≤ 45 Hz) sound waves, on the enhancement of intrasinus drug deposition. Methods: 81m Kr-gas ventilation study was performed in a plastinated human cast with and without the addition of vibrating acoustic airflow. Similarly, intrasinus drug deposition in a nasal replica using gentamicin as a marker was studied with and without the superposition of different modes of acoustic airflow. Results: Ventilation experiments demonstrate that no sinus ventilation was observed without acoustic airflow although sinus ventilation occurred whatever the modes of acoustic airflow applied. Intrasinus drug deposition experiments showed that the high frequency acoustic airflow led to 4-fold increase in gentamicin deposition into the left maxillary sinus and to 2fold deposition increase into the right maxillary sinus. Besides, the low frequency acoustic airflow demonstrated a significant increase of 4-fold and 2-fold in the right and left maxillary sinuses respectively. Conclusion: We demonstrated the benefit of different modes of vibrating acoustic airflow for maxillary sinus ventilation and intrasinus drug deposition. The degree of gentamicin deposition varies as a function of frequency of the vibrating acoustic airflow and the geometry of the ostia.

Forensic science review, 2015

Aim: We investigated the impact of vibrating acoustic airflow, the high frequency (f ≥ 100 Hz) an... more Aim: We investigated the impact of vibrating acoustic airflow, the high frequency (f ≥ 100 Hz) and the low frequency (f ≤ 45 Hz) sound waves, on the enhancement of intrasinus drug deposition. Methods: 81m Kr-gas ventilation study was performed in a plastinated human cast with and without the addition of vibrating acoustic airflow. Similarly, intrasinus drug deposition in a nasal replica using gentamicin as a marker was studied with and without the superposition of different modes of acoustic airflow. Results: Ventilation experiments demonstrate that no sinus ventilation was observed without acoustic airflow although sinus ventilation occurred whatever the modes of acoustic airflow applied. Intrasinus drug deposition experiments showed that the high frequency acoustic airflow led to 4-fold increase in gentamicin deposition into the left maxillary sinus and to 2fold deposition increase into the right maxillary sinus. Besides, the low frequency acoustic airflow demonstrated a significant increase of 4-fold and 2-fold in the right and left maxillary sinuses respectively. Conclusion: We demonstrated the benefit of different modes of vibrating acoustic airflow for maxillary sinus ventilation and intrasinus drug deposition. The degree of gentamicin deposition varies as a function of frequency of the vibrating acoustic airflow and the geometry of the ostia.

Summary: Introduction: marijuana is most highly consumed abuse substance in America and Europe af... more Summary: Introduction: marijuana is most highly consumed abuse substance in America and Europe after alcohol. In Uruguay, the prevalence is close to 23%. The active ingredient, delta 9-tetrahydrocannabinol, is responsible for its psychoactive effects. The main source of access for a child involves a relative and/or neighbor. Intoxication may be more severe in children, In 2013,.cannabis-sale regulating Act 19.172 was approved in Uruguay, and it generated a new potentially risky scenario for children. Objective: report clinical cases of severe unintentional intoxication from cannabis between March and June 2017, and analyze circumstances that led to exposure, clinical manifestations, severity and evolution. Clinical observation: 4 children (9 months, 1, 2 and 8 years of age) were assisted. In all cases, they had ingested cannabis in their home environment. They presented severe neurological symptoms: depressed level of consciousness, convulsive seizures, dystonia, ataxia, irritability. They required supportive measures, digestive decontamination and additional laboratory tests. Urine screening was positive in 4 cases. In 2, we performed confirmatory technique. As per the Poisoning Severity Score, all children suffered moderate intoxication. They were assisted jointly by a clinical toxicologist. Conclusions: children showing predominantly acute neurological symptoms with no apparent cause can be the subject of severe cannabis intoxication, especially when cannabis consumption takes place in their household environments. Surveillance is needed and future research will certainly contribute to the creation of prevention strategies with the purpose of reducing the potential unwanted consequences of this new scenario for children. Key words: Cannabis; Poisoning; Neurotoxicity syndromes; Marijuana use; Consciousness disorders

Anfamed, Dec 23, 2014

The consumption of alcohol and cocaine can affect pregnant’s health, fetus´s health and child dev... more The consumption of alcohol and cocaine can affect pregnant’s health, fetus´s health and child development, so it is important to recognize fetal exposure to these substances in order to plan appropriatemonitoring and timely interventions. The aim of the study was to determine the frequency of alcohol consumption and cocaine intake in the Hospital Pereira Rossell’s (Montevideo, Uruguay) population.The investigation consisted on an observational analytic cross-sectional study of 240 puerperal women and their children born at the Hospital Pereira Rossell from November 2010 to March 2011. The method used for the identification of free fatty acid ethyl esters in meconium of newborns was developed at the Polo Tecnologico de Pando, Facultad de Quimica, Universidad de la Republica for this investigation. The media of maternal age was 25; Alcohol consumption during pregnancy was admitted by 81 women, and the presence of free fatty acids ethyl esters was confirmed in 113 cases (49.78%); the consumption of cocaine hydrochloride and freebase cocaine was positive in 9.25% cases. Alcohol consumption was identified in half of pregnant women. The consumption of cocaine derivatives in the population studied was high. Exposed fetus can be identified with the analysis of meconium samples, with more certainty than by reports of patients.

Arch. pediatr. …, 2010

Título: Consumo de pasta base de cocaína en Uruguay en el embarazo, su incidencia, característica... more Título: Consumo de pasta base de cocaína en Uruguay en el embarazo, su incidencia, características y repercusiones/Cocaine base paste consumption during pregnancy in Uruguay, its incidence, characteristics and repercussions

Summary Cocaine base paste, CBP (the acronym in Spanish for "pasta base de cocaína") co... more Summary Cocaine base paste, CBP (the acronym in Spanish for "pasta base de cocaína") consumption is a major health and social problem in several Latin- American countries, including Uruguay. Currently, there are no published scientific evidences of CBP central actions that may explain the syntomatology observed in its consumers. CBP is a cocaine-smoking form. Although subjective effects induced by CBP

Environmental Monitoring and Assessment, 2014

The objective of this study was to predict chloroform formation resulting from the process of dis... more The objective of this study was to predict chloroform formation resulting from the process of disinfecting water, particularly trihalomethane which is most frequently produced. A statistical model was used which included repeated measurements of water parameters used for monitoring water quality at 51 sites covering the municipal water system of Montevideo. Samples were taken considering different seasons from June 2009 to July 2011 in Montevideo. Total samples (n= 330) were analytically studied using the headspace-gas chromatography method coupled with mass spectrometry. Chloroform was the dependent variable and the covariables were pH, temperature, free chlorine, and total chlorine. A Tobit analysis with an unstructured correlation matrix was performed, and a significant interaction was found between pH and free chlorine for the prediction of chloroform formation. We concluded that parameters for the continuous control of water quality for consumption can be used to predict the levels of chloroform that may be present. Given the large measurement to variability found in the repeated measurements, the use of averages that include more than one season is not recommended to determine the degree of compliance with acceptable levels established by norms.

Presentado a : IUNS 20th International Congress of Nutrition. Granada, Espana. 15-20 setiembre 2013

Pharmacology Biochemistry and Behavior

Pharmacology Biochemistry and Behavior

Revista chilena de pediatría, Jun 1, 2017

Introduction: Post partum depresion (DPP) is the most frequent psquiatric disorder in pregnant wo... more Introduction: Post partum depresion (DPP) is the most frequent psquiatric disorder in pregnant woman and it may affect the neurodevelopment of their offspring. Our goal was to analyze the association between maternal depressive symptoms at 6 months after birth and child's neurodevelopmental disorders at 18 months-old, in a homogeneous population characterized by low socioeconomic and cultural level. Patients and Methods: A prospective cohort study was conducted. There were included 127 healthy postpartum women and their infants. A structured interview was performed, which included patronymic data and family perception before discharge. Binomial monitoring took place at 6 months postpartum, when was applied the Beck test for depression and anxiety to mothers; children´s neurodevelopment at 18 month-old was evaluated by Lezine Revised Brunettest. Results: The sample consisted of 125 women and their children. The mean age was 24.5 year old (SD 6.02); 30.6 % had completed less than 6 years of formal education. The incidence of moderate to severe postpartum depression at 6 months after birth was 20%. The overall development score mean was 73.52 (SD 8.06) in the depression population and 76.97 (SD 8.07) in the population without depression (p = 0.04). The development coefficient was 69.08 (SD: 10.35) in the depression population and 74.11 (SD 0.67) in the population without depression (p = 0.01). Conclusions: The incidence of moderate to severe DPP was 20%. Persistent DPP in a vulnerable socioeconomic context has impact on child development.

Cogent Environmental Science, Aug 31, 2018

The use of chlorine to disinfect water produces a series of by-products, particularly trihalometh... more The use of chlorine to disinfect water produces a series of by-products, particularly trihalomethanes. This is important given that there is a recognized association with different types of cancer after prolonged exposure, as well as with probable adverse effects on reproduction, especially in relation to offspring. The concentrations of these organic compounds vary greatly depending on the season and the conditions involved in providing water for consumption. This study was aimed at determining the geographic distribution pattern of chloroform in the city of Montevideo, and correlating that with the characteristics of the water distribution network. A total of 400 samples were taken from a sampling network between 2009 and 2015. Chloroform was identified by analyzing these samples using the headspace gas chromatography/mass spectrometry method. Data regarding piping length, diameter, and type of material were obtained. A geographic information system was constructed and hot spots were analyzed using the Getis-Ord G i * statistic. A neighborhood piping density index was also proposed. The analysis found two zones in the city: hot and cold spots. The proposed index showed an increase in the G i * statistic as the neighborhoods' piping density increased, with a strong correlation. In addition, the highest G i * statistic values corresponded to

Journal Fur Praktische Chemie, Aug 1, 1999

Archivos De Pediatria Del Uruguay, Mar 1, 2014

Introducción: el consumo de cafeína es un hábito extendido a nivel mundial, destacándose el mate ... more Introducción: el consumo de cafeína es un hábito extendido a nivel mundial, destacándose el mate en los países del cono sur como una fuente importante de ingesta. Objetivos: valorar la ingesta de cafeína en el embarazo, el aporte de las diferentes fuentes de ingesta y su relación con el peso al nacer. Metodología y población: se realizó un estudio observacional, analítico de corte transversal que incluyó 240 puérperas y sus recién nacidos sanos de 35 semanas de gestación o mayores. Resultados: la media de edad materna fue de 24,96 (DE=6,01), Estaban casadas o convivían con su pareja 179 mujeres (74,58%). De ellas 67 (28,03%) eran primigestas. La media de controles del embarazo fue 7,31 (DE=3,32) y nacieron por cesárea 70 (29,17%). Las características de los recién nacidos reflejan los criterios de inclusión referidos: 35 semanas de gestación o mayores, vigorosos, internados junto a su madre luego del nacimiento. Durante todo el embarazo la fuente principal de cafeína fue la ingesta de mate. La media de consumo de cafeína fue de 273,99 mg/día; el consumo de mate es la principal fuente de cafeína con una media de 240 mg/día, aportando un 85% de la ingesta diaria de cafeína. Se observó consumo de cafeína mayor de 300 mg/día en 77 embarazadas, 32% de la muestra. La ingesta de cafeína mayor a 300 mg/día se asocia al nacimiento de un niño pequeño para la edad gestacional, la ingesta de 100 mg de cafeína por día disminuye el peso al nacer en 38 g, independientemente del índice de masa corporal y el hábito de fumar. Conclusiones: el consumo de cafeína es elevado en las embarazadas en Uruguay, superando los 300 mg diarios en 32% de la muestra. La ingesta de mate es la fuente principal de cafeína en esta población. El consumo de cafeína mayor a 300 mg diarios se asocia a mayor riesgo de recién nacidos pequeños para la edad gestacional. En vistas a la evidencia científica actual debería implementarse una adecuada información para lograr un descenso del consumo de mate y cafeína durante la gestación.

Consumo de pasta base de cocaína y cocaína en mujeres durante el embarazo, 2016

Esta publicación reúne un conjunto de investigaciones referidas al consumo de pasta base de cocaí... more Esta publicación reúne un conjunto de investigaciones referidas al consumo de pasta base de cocaína y cocaína en mujeres durante el embarazo y en las primeras etapas posteriores al parto, realizadas por el equipo de investigación interdisciplinario Infancia 2020, de la Universidad de la República, Uruguay. Se comparten aproximaciones desde el campo de la salud, la bioquímica y la antropología.