Trait coordination at leaf level explains the resistance to excess light stress in shade-tolerant tropical tree species.

Plant functioning in response to the environment is an important issue for vegetation reassembly of degraded lands because of both low and excessive sunlight influence the performance of young plants. However, how shade-tolerant tree species deal with excess of light energy remains unclear due to the contrasting results among studies and the subjective classifications of species shade tolerance. From a quantitative classification of shade tolerance of 12 tropical tree species planted in the field under contrasting light conditions, we hypothesized that shade-tolerant species are capable of effective long-term acclimation to high-light conditions. Plant size and survival of species were measured at the beginning and 38 months after planting. We also measured functional traits associated with carbon economy and non-photochemical energy dissipation. Under high-light condition, more light-demanding species showed higher growth rates associated with higher values of functional traits that improve the CO2 assimilation capacity. By contrast, more shade-tolerant species showed higher survival that was associated with higher values of qN, leaf K contents and leaf thickness. The concomitant increase in these traits, as well as their greater plasticity to light in WUEi, Fv/Fm and qN, confers on these species strong photoprotection to avoid high-light stress and to persist under open field conditions. The results challenge the common assumption that only fast-growing and light-demanding tree species are suitable for vegetation reassembly in full sunlight conditions and to improve the environmental conditions for other species.

Photosynthesis, growth, and survival in seedlings of four tropical fruit-tree species under intense radiation

In the Amazon region, agroforestry systems (AFSs) are recommended as a sustainable production alternative for local communities. A common component in Amazonian AFSs are tropical fruit trees, which can form the canopy or grow in the understory. In this study, we evaluated the effect of high radiation on photosynthesis, growth and seedling survival of four Amazonian fruit-tree species: Theobroma cacao, Eugenia stipitata, Inga edulis and Psidium guajava. Growth, chlorophyll fluorescence, gas exchange, and leaf pigments were measured in seedlings of each species grown for 12 months inside shade houses with low (8%), medium (30%) and high relative illumination (100%). Eugenia stipitata and T. cacao had the lowest acclimation capacity to high solar radiation, followed by I. edulis. Therefore, these species must be grown under intermediate light levels in early growth stages, to protect them from direct sunlight. In contrast, P. guajava seedlings demonstrated high tolerance to elevated radiation, therefore, this species can be planted under full sunlight. (AU)

Correction: Net Primary Productivity and Edaphic Fertility in Two Pluvial Tropical Forests in the Chocó Biogeographical Region of Colombia.

[This corrects the article DOI: 10.1371/journal.pone.0168211.].

Net Primary Productivity and Edaphic Fertility in Two Pluvial Tropical Forests in the Chocó Biogeographical Region of Colombia.

The net primary productivity (NPP) of tropical forests is a key process of the carbon cycle and therefore for the mitigation of global climate change. It has been proposed that NPP is limited by the availability of soil nutrients in lowland tropical forests and that belowground NPP decreases as edaphic fertility increases. This hypothesis was evaluated in two localities (Opogodó and Pacurita) of the Chocó Biogeographical region, one of the rainiest of the world, where the aboveground (litter and wood) and belowground (fine and coarse roots) components of NPP were measured. Fertility parameters (pH, nutrients, and texture) were also determined and related to NPP. Total NPP was similar between locations (23.7 vs. 24.2 t ha-1 year-1 for Opogodó and Pacurita, respectively). However, components of NPP showed differences: in Pacurita, with steeper topography, NPP of wood and coarse roots were higher; therefore, differences of topography and drainage between localities probably affected the NPP of wood. On the other hand, soils of Opogodó, where NPP of fine roots was higher, showed higher contents of sand, N+, and organic matter (OM). With the increase of pH, OM, N+, K, Mg, and sand, the NPP of leaves and fine roots as well as the percentage of NPP belowground also increased, which suggests NPP limitation by multiple nutrients. The increase of NPP belowground with the availability of edaphic nutrients evidenced a redistribution of the aboveground and belowground components of NPP with the increase of soil fertility in oligotrophic systems, probably as a mechanism to improve the capture of resources.

Dinámica de raíces finas y su relación con la fertilidad edáfica en bosques pluviales tropicales del Chocó biogeográfico colombiano / Fine root dynamics and its relationship with soil fertility in tropical rainforests of Chocó

Resumen:Las raíces finas juegan un papel importante en la adquisición de agua y minerales del suelo, el balance global del carbono y la mitigación del cambio climático. La dinámica (productividad-PRF y recambio-RRF) de raíces finas es esencial para el ciclo de nutrientes y balance de carbono de los ecosistemas forestales. La disponibilidad de agua y nutrientes determina de manera significativa la PRF y el RRF. Se ha planteado la hipótesis de que la dinámica de raíces finas aumenta con la disponibilidad de los recursos del suelo en bosques tropicales. Para probar esta hipótesis en las selvas tropicales del Chocó (ecosistemas con las más altas tasas de precipitación en el mundo), se establecieron cinco parcelas permanentes de una hectárea en las localidades de Opogodó y Pacurita, donde la PRF y RRF se midieron a 0-10 cm y 10-20 cm de profundidad. La medición de la PRF se realizó por el método de cilindros de crecimiento. La tasa de RRF se midió como la PRF/ biomasa media anual. Además, se midieron los parámetros de fertilidad del suelo (pH, nutrientes y textura) y se evaluó su asociación con PRF y RRF. Se encontró que ambos sitios presentan suelos pobres en nutrientes. Las localidades difieren en características edáficas; Opogodó tiene suelos arenosos y topografía plana, y Pacurita tiene suelos arcillosos, ricos en aluminio y topografía montañosa. En Opogodó la PRF fue (media ± DE) de 6.50 ± 2.62 t/ha.año. En Pacurita la PRF fue 3.61 ± 0.88 t/ha.año. Igualmente, en Opogodó el RRF fue mayor que en Pacurita (1.17 /año y 0.62 /año, respectivamente). El RRF y la PRF fueron mayores en la superficie del suelo (10 cm de profundidad). La PRF y el RRF mostraron correlación positiva con el pH, MO, N total, K, Mg, y arena; mientras que, las correlaciones fueron negativas con la CICE, Al, limo y arcilla. El porcentaje de arena fue el parámetro que mejor explica la variación en la PRF. La tasa negativa de la RRF fue explicada por la disponibilidad de Al. Los resultados evidenciaron un aumento en la dinámica de las raíces finas con la fertilidad del suelo a escala local, lo que sugiere que en selvas tropicales con suelos oligotróficos, las raíces finas tienden a proliferar rápidamente en pequeños parches de suelo ricos en arena y nutrientes.

Abstract:The fine roots play an important role in the acquisition of water and minerals from the soil, the global carbon balance and mitigation of climate change. The dynamics (productivity and turnover) of fine roots is essential for nutrient cycling and carbon balance of forest ecosystems. The availability of soil water and nutrients has significantly determined the productivity and turnover of fine roots. It has been hypothesized that fine roots dynamics increases with the availability of soil resources in tropical forest ecosystems. To test this hypothesis in tropical rainforests of Chocó (ecosystems with the highest rainfall in the world), five one-ha permanent plots were established in the localities of Opogodó and Pacurita, where the productivity and turnover of fine roots were measured at 0-10 cm and 10-20 cm depth. The measurement of the fine root production was realized by the Ingrowth core method. The fine root turnover was measured like fine roots production divided mean annual biomass. In addition, soil fertility parameters (pH, nutrients, and texture) were measured and their association with productivity and turnover of fine roots was evaluated. It was found that the sites had nutrient-poor soils. The localities also differ in soil; Opogodó has sandy soils and flat topography, and Pacurita has clay soils, rich in aluminum and mountainous topography. In Opogodó fine root production was 6.50 ± 2.62 t/ha.yr (mean ± SD). In Pacurita, fine root production was 3.61 ± 0.88 t/ha.yr. Also in Opogodó, the fine root turnover was higher than in Pacurita (1.17 /y and 0.62 /y, respectively). Fine root turnover and production in the upper soil layers (10 cm upper soil) was considerably higher. Productivity and turnover of fine roots showed positive correlation with pH and contents of organic matter, total N, K, Mg, and sand; whereas correlations were negative with ECEC and contents of Al, silt, and clay. The percentage of sand was the parameter that best explained the variations of fine root production. The fine root turnover was negatively explained by soil Al availability. Results suggested the increase of fine root dynamics with soil fertility at a local scale, which also indicates that under the oligotrophic conditions of soils in tropical rainforests, fine roots tend to proliferate rapidly in small patches of soil rich in sand and nutrients. Rev. Biol. Trop. 64 (4): 1709-1719. Epub 2016 December 01.

[Fine root dynamics and its relationship with soil fertility in tropical rainforests of Chocó]. / Dinámica de raíces finas y su relación con la fertilidad edáfica en bosques pluviales tropicales del Chocó biogeográfico colombiano.

The fine roots play an important role in the acquisition of water and minerals from the soil, the global carbon balance and mitigation of climate change. The dynamics (productivity and turnover) of fine roots is essential for nutrient cycling and carbon balance of forest ecosystems. The availability of soil water and nutrients has significantly determined the productivity and turnover of fine roots. It has been hypothesized that fine roots dynamics increases with the availability of soil resources in tropical forest ecosystems. To test this hypothesis in tropical rainforests of Chocó (ecosystems with the highest rainfall in the world), five one-ha permanent plots were established in the localities of Opogodó and Pacurita, where the productivity and turnover of fine roots were measured at 0-10 cm and 10-20 cm depth. The measurement of the fine root production was realized by the Ingrowth core method. The fine root turnover was measured like fine roots production divided mean annual biomass. In addition, soil fertility parameters (pH, nutrients, and texture) were measured and their association with productivity and turnover of fine roots was evaluated. It was found that the sites had nutrient-poor soils. The localities also differ in soil; Opogodó has sandy soils and flat topography, and Pacurita has clay soils, rich in aluminum and mountainous topography. In Opogodó fine root production was 6.50 ± 2.62 t/ha.yr (mean ± SD). In Pacurita, fine root production was 3.61 ± 0.88 t/ha.yr. Also in Opogodó, the fine root turnover was higher than in Pacurita (1.17 /y and 0.62 /y, respectively). Fine root turnover and production in the upper soil layers (10 cm upper soil) was considerably higher. Productivity and turnover of fine roots showed positive correlation with pH and contents of organic matter, total N, K, Mg, and sand; whereas correlations were negative with ECEC and contents of Al, silt, and clay. The percentage of sand was the parameter that best explained the variations of fine root production. The fine root turnover was negatively explained by soil Al availability. Results suggested the increase of fine root dynamics with soil fertility at a local scale, which also indicates that under the oligotrophic conditions of soils in tropical rainforests, fine roots tend to proliferate rapidly in small patches of soil rich in sand and nutrients.

Intra annual seed production and availability of two morphotypes of Brosimum rubescens taubert in forests of the Colombian Amazon / Producción y disponibilidad intra anual de semillas de dos morfotipos de Brosimum rubescens Taubert en bosques de la amazonía colombiana

We assessed the reproductive phenology, production, and availability of seeds for two morphotypes of Brosimum rubescens Taub. (Moraceae), locally known as black palosangre (BP) and white palosangre (WP) during an annual cycle in a 20-ha mega plot located in a primary forest at the El Zafire Biological Station, in the Colombian Amazon. We found that 87% and 41% of potentially reproductive individuals of BP and WP respectively, was fertile and the production of reproductive structures was variable within and between morphotypes. The phenological pattern was seasonal in both morphotypes, characterized by flowering at the end of the dry season and fruiting at the start of the rainy season. BP produced and aborted large amounts of infructescences (approximately 21743), possibly as a response to satiate predators. Relative predation in terms of pre-dispersion of seeds was similar in both morphotypes, with a greater damage generated by a Scolytidae Curculionidae (Coleoptera) and to a lesser degree by frugivorous vertebrates. The number of mature fruits, total seeds, and removed seeds was similar for both morphotypes. Differences in the amount of reproductive structures and in the timing of phenophases between morphotypes decreased the competition and contributed to their coexistence. It seems that in undisturbed forests seed limitation could be more conditioning for WP, while other limitations after fruit and seed production could occur in BP.

Se evaluó la fenología reproductiva, producción y disponibilidad de semillas de dos morfotipos de Brosimum rubescens Taub. (Moraceae), conocidos localmente como palosangre negro (PN) y palosangre blanco (PB), durante un ciclo anual en una megaparcela de 20 ha localizada en bosques primarios de la Estación Biológica El Zafire, Amazonía colombiana. Se encontró que estuvieron fértiles el 87% y 41% de los individuos potencialmente reproductivos de PN y PB, respectivamente. La producción de estructuras reproductivas fue variable dentro y entre morfotipos. El patrón fenológico fue estacional en ambos: florecieron al final de la época seca y fructificaron al inició de la lluviosa. Aunque en PB aparentemente ocurre limitación en la polinización, la maduración de los óvulos fecundados es más eficiente que en PN. Este último produjo y abortó abundante cantidad de infrutescencias, posiblemente para saciar depredadores. En ambos morfotipos la depredación relativa pre-dispersión de las semillas fue similar, siendo mayor el daão generado por un Curculionidae Scolytidae (Coleóptera) y menor por frugívoros vertebrados. El número de frutos maduros, semillas totales y semillas removidas también fue similar entre morfotipos. Diferencias en la cantidad de estructuras reproductivas y en el tiempo de manifestación de las fenofases entre morfotipos, disminuyen la competencia y contribuyen a su coexistencia. Aparentemente, en bosques no disturbados la limitación de semillas podría ser más condicionante para PB, pero otras limitaciones posteriores a la producción de frutos y semillas podrían presentarse en PN.

Efectos de la iuuminación relativa y la fertiliación sobre el crecimiento de pplántulas de roble andino en vivero / Effects of Light Intensity and Fertilization on the Growth of Andean Oak Seedlings at Nursery

Quercus humboldtii es una especie vegetal nativa de mucha importancia en Colombia por su uso en repoblamiento forestal y restauración de tierras altoandinas degradadas. La especie se encuentra fuertemente amenazada y es necesario establecer programas de propagación de la misma. Sin embargo, poco se conoce sobre sus exigencias nutricionales y lumínicas. El objetivo de este estudio fue determinar los efectos simples y combinados de la iluminación relativa (IR) y la fertilización sobre el crecimiento de plántulas de Q. humboldtii en vivero. Para esto se establecieron en combinación tres condiciones contrastantes de iluminación relativa (alta, media y baja IR) y nueve tratamientos de fertilización: completa (TC), con un elemento faltante (-N, -P, -K, -Ca, -Mg, -S, -B) y un testigo sin fertilización (T0). La condición de IR media presentó el mejor desarrollo de las plántulas. Todos los tratamientos con deficiencias nutricionales produjeron disminuciones en el desarrollo de las plántulas con respecto a TC, excepto en el tratamiento -B. El N fue el elemento más limitante, con rendimientos similares a los del tratamiento testigo. El orden de limitación que produjeron los tratamientos aplicados siguió la secuencia: T0,-N > -Ca, -K, - P > -Mg, -S > TC,-B. No se detectó interacción significativa IR x Fertilización sobre el desarrollo de las plántulas.

Quercus humboldtii is a native plant species of great importance in Colombia for use in reforestation and restoration of degraded Andean highlands. The species is highly threatened and it is necessary to establish programs of propagation and planting. However, little is known about their nutritional and light requirements. The aim of this study was to determine the effects of single and combined relative illumination (IR) and fertilization on the growth of seedlings of Q. humboldtii at nursery. For this purpose three contrasting IR regimes (high, medium, and low IR) and nine fertilization treatments were established: complete (TC), a missing nutrient (-N,-P,-K,-Ca,-Mg, -S,-B) and a control without fertilization (T0). The best development of seedlings was showed in the medium IR condition. All treatments with a lacking nutrient showed decreases in seedling development regarding TC, except in the -B treatment. Nitrogen was the most limiting nutrient yielding biomass similar to that of T0. The impact of nutrient limitation on seedling performance was in the following order:-N>-Ca,-K,-P>-Mg,-S>-B. No significant interaction IR x Fertilization was detected on seedling development.

[Soil and forest structure in the Colombian Amazon]. / Relación entre suelos y estructura del bosque en la Amazonía colombiana.

Forests structural differences could result of environmental variations at different scales. Because soils are an important component of plant's environment, it is possible that edaphic and structural variables are associated and that, in consequence, spatial autocorrelation occurs. This paper aims to answer two questions: (1) are structural and edaphic variables associated at local scale in a terra firme forest of Colombian Amazonia? and (2) are these variables regionalized at the scale of work? To answer these questions we analyzed the data of a 6ha plot established in a terra firme forest of the Amacayacu National Park. Structural variables included basal area and density of large trees (diameter > or = 10cm) (Gdos and Ndos), basal area and density of understory individuals (diameter < 10cm) (Gsot and Nsot) and number of species of large trees (sp). Edaphic variables included were pH, organic matter, P, Mg, Ca, K, Al, sand, silt and clay. Structural and edaphic variables were reduced through a principal component analysis (PCA); then, the association between edaphic and structural components from PCA was evaluated by multiple regressions. The existence of regionalization of these variables was studied through isotropic variograms, and autocorrelated variables were spatially mapped. PCA found two significant components for structure, corresponding to the structure of large trees (G, Gdos, Ndos and sp) and of small trees (N, Nsot and Gsot), which explained 43.9% and 36.2% of total variance, respectively. Four components were identified for edaphic variables, which globally explained 81.9% of total variance and basically represent drainage and soil fertility. Regression analyses were significant (p < 0.05) and showed that the structure of both large and small trees is associated with greater sand contents and low soil fertility, though they explained a low proportion of total variability (R2 was 4.9% and 16.5% for the structure of large trees and small tress, respectively). Variables with spatial autocorrelation were the structure of small trees, Al, silt, and sand. Among them, Nsot and sand content showed similar patterns of spatial distribution inside the plot.

Relación entre suelos y estructura del bosque en la Amazonía colombiana

Soil and forest structure in the Colombian Amazon. Forests structural differences could result of environmental variations at different scales. Because soils are an important component of plant’s environment, it is possible that edaphic and structural variables are associated and that, in consequence, spatial autocorrelation occurs. This paper aims to answer two questions: (1) are structural and edaphic variables associated at local scale in a terra firme forest of Colombian Amazonia? and (2) are these variables regionalized at the scale of work? To answer these questions we analyzed the data of a 6ha plot established in a terra firme forest of the Amacayacu National Park. Structural variables included basal area and density of large trees (diameter≥10cm) (Gdos and Ndos), basal area and density of understory individuals (diameter<10cm) (Gsot and Nsot) and number of species of large trees (sp). Edaphic variables included were pH, organic matter, P, Mg, Ca, K, Al, sand, silt and clay. Structural and edaphic variables were reduced through a principal component analysis (PCA); then, the association between edaphic and structural components from PCA was evaluated by multiple regressions. The existence of regionalization of these variables was studied through isotropic variograms, and autocorrelated variables were spatially mapped. PCA found two significant components for structure, corresponding to the structure of large trees (G, Gdos, Ndos and sp) and of small trees (N, Nsot and Gsot), which explained 43.9% and 36.2% of total variance, respectively. Four components were identified for edaphic variables, which globally explained 81.9% of total variance and basically represent drainage and soil fertility. Regression analyses were significant (p<0.05) and showed that the structure of both large and small trees is associated with greater sand contents and low soil fertility, though they explained a low proportion of total variability (R² was 4.9% and 16.5% for the structure of large trees and small tress, respectively). variables with spatial autocorrelation were the structure of small trees, Al, silt, and sand. Among them, Nsot and sand content showed similar patterns of spatial distribution inside the plot. Rev. Biol. Trop. 59 (3): 1307-1322. Epub 2011 September 01.

Las diferencias estructurales del bosque pueden ser el producto de variaciones ambientales a diferentes escalas, entre ellas los suelos. Para evaluar tal asociación, se usaron los datos de estructura del bosque y de suelos de una parcela de 6ha establecida en un bosque de tierra firme de la Amazonía colombiana. Las variables edáficas y estructurales se redujeron con un análisis de componentes principales (ACP) y un análisis de regresión múltiple verificó si existía asociación entre los componentes edáficos y estructurales del ACP. La regionalización de las variables de estudio se verificó con variogramas isotrópicos; además, se construyeron mapas de distribución espacial. El ACP de las variables estructurales identificó dos componentes: dosel y sotobosque, los cuales explicaron el 43.9 y 36.2% de la varianza total, respectivamente; para las variables edáficas los cuatro primeros componentes explicaron globalmente el 81.9% de la varianza total. Los análisis de regresión mostraron que tanto el dosel como el sotobosque se asocian con mayores contenidos de arena y baja fertilidad del suelo (p<0.05), pero explicaron una proporción baja de la variabilidad total (R²=4.9% para dosel y 16.5% para sotobosque). Las tres variables de la estructura del sotobosque, Al, limo y arena presentaron autocorrelación espacial.

Fenología reproductiva y productividad de Oenocarpus bataua (Mart.) en bosques inundables del Chocó Biogeográfico, Colombia / Reproductive phenology and fruit productivity of Oenocarpus bataua (Mart.) in flooded forests in the Chocó Biogeographic region, Colombia

Oenocarpus bataua (Mart.) es una especie de palma que conforma rodales altamente densos en bosques inundables del Chocó Biogeográfico. Es considerada promisoria porque sus frutos contienen proteínas y aceite de alta calidad; por ello, el manejo sostenible de estos bosques y la cosecha periódica de sus frutos pueden proveer alimento e ingresos monetarios a las comunidades locales y, así, mejorar su calidad de vida. Se estudió la fenología reproductiva y la productividad de frutos de esta especie en dos comunidades vegetales: milpesal puro-MP (inundable esporádicamente) y murrapal mezclado-MM (inundable periódicamente), con densidades específicas de 278 y 82 individuos.ha-1; respectivamente. En cada comunidad se estableció un bloque con 12 parcelas de 20 × 25 m, donde se marcaron las palmas reproductivas (166 en MP y 49 en MM). Quincenalmente, entre noviembre de 1999 y diciembre de 2001 (26 meses), y entre noviembre de 2006 y mayo de 2009 (31 meses), se registró el estado fenológico de cada palma. Los patrones reproductivos fueron cuantificados mediante el índice de actividad y las proporciones de ocurrencia de cada fenofase fueron evaluadas mediante diferentes modelos de regresión. De acuerdo con éstos, un ciclo fenológico de la especie a nivel poblacional, desde la aparición del botón floral y posterior exposición de las inflorescencias, hasta el desarrollo, maduración y caída de los frutos dura ca. 4 años. No se encontró una relación significativa entre la precipitación y la ocurrencia de las fenofases, por lo que su ciclo fenológico parece responder a factores endógenos. El pico de producción de frutos maduros en la población ocurrió cada 34 meses y se presentó en 47 y 26 por ciento de las palmas en MP y MM. La productividad de frutos por ciclo fue 3014 y 330 kg.ha-1; respectivamente.

Oenocarpus bataua (Mart.) is a palm species forming highly dense stands in flooded forests of the Chocó Biogeographic region. This species is considered promising because its fruits contain protein and high quality oil; therefore, periodic harvests of fruits are a potential source of food and income to local communities and could contribute to improve their living conditions. We studied the reproductive phenology and productivity of fruits of this species in two forest types: mono-dominant stands, called locally "pure milpesal"-MP (occasionally flooded), and more heterogeneous forests, called "mixed murrapal"-MM (periodically flooded), with specific densities of 278 and 82 individuals.ha-1; respectively. In each forest type, we established a block with 12 plots of 20 × 25 m, where the reproductive palms were labeled (166 in MP and 49 in MM). Every other week, from November 1999 until December 2001 (26 months) and from November 2006 until May 2009 (31 months), the phenological state of each previously labeled palm was recorded. The phenological behavior was quantified using the Activity Index and the observed proportions of each phenophase along time were evaluated with different regression models. According to these models, a phenological cycle of the species at the population level lasts about 4 years. We could not find any relationship between rainfall and phenological variables; therefore, the phenological cycle appears to respond to endogenous factors. The production peak of ripe fruits in the population occurred every 34 months in 47 and 26 percent in all palms in MP and MM. Fruit productivity per cycle was 3014 and 330 kg.ha-1; respectively.

Estimated risks of water and saliva contamination by phthalate diffusion from plasticized polyvinyl chloride.

Phthalates are additives commonly used to convert hard polyvinyl chloride (PVC) resins into flexible and workable plastics employed in the production of chewable rubber toys and other soft-plastic products. In theory, phthalates can diffuse in small quantities to the surface of a product, and from there they can enter the environment and the human body. The purpose of this study was to determine the diffusion of phthalates from plasticized PVC in water and artificial saliva; to determine the migration of di(2-ethylhexyl) (DEHP) phthalate in human saliva using gas chromatography; to compare the experimental values with theoretical values calculated using a model based on the principles of molecular diffusion in fluids; and to use the experimental values to estimate daily doses of DEHP received by Mexican children and infants using plastic and soft-plastic products (e.g., pacifiers, chewable toys, and bottles). Our findings indicated phthalate diffusion of 0.36 microg/cm2 per hour and 4.10 microg/cm2 per hour, respectively, in water and artificial saliva. The average value of phthalate diffusion in vivo was 6.04 microg/cm2 per hour. The daily oral phthalate exposure in Mexican infants and toddlers from oral use of rubber toys and soft-plastic products is 18.12 microg/kg. These daily doses are considerably lower than the maximum daily phthalate intake recommended by an international public health committee.

[Infant exposure to potentially toxic plasticizers in products for oral use]. / Exposición infantil a plastificantes potencialmente tóxicos en productos de uso oral.

OBJECTIVE: To estimate the prevalence of oral product use in children less than three years of age, and to measure the concentration of phthalates as potentially toxic products. MATERIAL AND METHODS: In 1999, 199 mothers of children living in the city of Toluca agreed to household interviews. Samples of oral products used by the children were taken and analyzed by gas chromatography to identify and quantify phthalate concentrations, to estimate the daily intake of phthalates from this source. RESULTS: The prevalence of oral product use was 13%. Male infants less than 18 months of age of low socioeconomic level used them more frequently. The concentrations ranged from traces to 67% weight. The mean exposure to products manufactured with polyvinyl chloride and phthalates was 13.94 microg/kg/day (95% CI 9.08, 18.89). CONCLUSIONS: The daily dose of phthalate intake from products for infants to suck or bite did not exceed the recommended limit established in other countries. Nevertheless, other sources can contribute to increase the total dose. Since some phthalates are harmful to the reproductive system in animals and this potential effect may also be expected in humans, it is necessary to assess other sources and determine exposure using biomarkers.

Exposición infantil a plastificantes potencialmente tóxicos en productos de uso oral / Infant exposure to potentially toxic plasticizers in products for oral use

OBJETIVO: Determinar la prevalencia en el uso de productos infantiles orales entre menores de tres años de edad y medir su concentración de ftalatos, sustancias potencialmente tóxicas. MATERIAL Y MÉTODOS: Se realizó, en 1999, una entrevista domiciliaria a 199 madres de niños del área metropolitana de la ciudad de Toluca. Por cromatografía de gases se identificaron y cuantificaron diversos ftalatos de productos de uso oral empleados por los niños participantes y se estimó la contribución de estas fuentes a la ingesta diaria de ftalatos. RESULTADOS: La prevalencia de uso de estos productos fue de 13 por ciento, siendo mayor entre los niños, menores de 18 meses de edad, pertenecientes al estrato socioeconómico bajo. Las concentraciones variaron desde trazas hasta 67.0 por ciento del peso. La exposición media calculada proveniente de los productos manufacturados con policloruro de vinilo y ftalatos fue de 13.94 µg/ kg de peso/día, IC 95 por ciento (9.08, 18.89). CONCLUSIONES: La exposición a ftalatos proveniente de productos para chupar o morder se encuentra dentro de los límites reportados en otros países; sin embargo, otras fuentes pueden incrementarla. Dado que algunos ftalatos han mostrado ser tóxicos en el sistema reproductivo, y este potencial efecto es plausible en el hombre, es necesaria la investigación de otras fuentes y determinar la exposición total a través de biomarcadores.

OBJECTIVE: To estimate the prevalence of oral product use in children less than three years of age, and to measure the concentration of phthalates as potentially toxic products. MATERIAL AND METHODS: In 1999, 199 mothers of children living in the city of Toluca agreed to household interviews. Samples of oral products used by the children were taken and analyzed by gas chromatography to identify and quantify phthalate concentrations, to estimate the daily intake of phthalates from this source. RESULTS: The prevalence of oral product use was 13 percent. Male infants less than 18 months of age of low socioeconomic level used them more frequently. The concentrations ranged from traces to 67 percent weight. The mean exposure to products manufactured with polyvinyl chloride and phthalates was 13.94 µg/kg/day (95 percent CI 9.08, 18.89). CONCLUSIONS: The daily dose of phthalate intake from products for infants to suck or bite did not exceed the recommended limit established in other countries. Nevertheless, other sources can contribute to increase the total dose. Since some phthalates are harmful to the reproductive system in animals and this potential effect may also be expected in humans, it is necessary to assess other sources and determine exposure using biomarkers.