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ENVIRONMENTAL RISK ASSESSMENT FOR LEAD EXPOSITION IN VETAGRANDE, ZACATECAS, MEXICO DIRECTORATE OF RESEARCH ON CHEMICAL SUBSTANCES AND ECOTOXICOLOGICAL.

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Presentation on theme: "ENVIRONMENTAL RISK ASSESSMENT FOR LEAD EXPOSITION IN VETAGRANDE, ZACATECAS, MEXICO DIRECTORATE OF RESEARCH ON CHEMICAL SUBSTANCES AND ECOTOXICOLOGICAL."— Presentation transcript:

1 ENVIRONMENTAL RISK ASSESSMENT FOR LEAD EXPOSITION IN VETAGRANDE, ZACATECAS, MEXICO DIRECTORATE OF RESEARCH ON CHEMICAL SUBSTANCES AND ECOTOXICOLOGICAL RISKS INE-SEMARNAT Mario Yarto-Ramírez; José Castro-Díaz; Arturo Gavilán-García AUTONOMOUS UNIVERSITY OF ZACATECAS Radiobiology Academic Entity Eduardo Manzanares Acuña 229th ACS National Meeting March 15th, 2005

2 CONTENT INTRODUCTION OBJECTIVES MATERIALS & METHODS RESULTS CONCLUSIONS RECOMMENDATIONS I II III IV V VI

3 INTRODUCTION I I INTRODUCTION II OBJECTIVE III MATERIALS & METHODS IV RESULTS V CONCLUSIONS RECOMMENDATIONS VI

4 INTRODUCTION I Mining in Zacatecas was developed by amalgamation from 1546 to 1800 (Ramírez, 1955).Mining in Zacatecas was developed by amalgamation from 1546 to 1800 (Ramírez, 1955). Tailings were dispersed by rivers and deposited in the Zacatecan Valley.Tailings were dispersed by rivers and deposited in the Zacatecan Valley. Some of the contaminated sites are currently used for agriculture & residential uses.Some of the contaminated sites are currently used for agriculture & residential uses. Importance was given to the site because of the CEC-NARAP on Mercury & the Substance Selection Group (Lead).Importance was given to the site because of the CEC-NARAP on Mercury & the Substance Selection Group (Lead). Previous research has shown that lead is found in higher concentration than other metals in Zacatecas.Previous research has shown that lead is found in higher concentration than other metals in Zacatecas. MINE CRUSHING SCREENING AMALGAMATION DISTILLATION WASHING

5 MAP OF THE STATE OF ZACATECAS

6 Vetagrande is a small community that grown in the vein of silver mine.Vetagrande is a small community that grown in the vein of silver mine habitants (2526 form 0 to 14 years old).7228 habitants (2526 form 0 to 14 years old).

7 Dust from tailings is carried out by wind and small particles are deposited within the town or breathed/ingested by the population.Dust from tailings is carried out by wind and small particles are deposited within the town or breathed/ingested by the population.

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9 Houses in Vetagrande have soil floors with high concentration of lead & streets are not paved.Houses in Vetagrande have soil floors with high concentration of lead & streets are not paved. Risk groups comprises children & pregnant women.Risk groups comprises children & pregnant women.

10 Mexican regulation (NOM-199-SSA1-2002) establishes a maximum permissible level of lead in blood of 10  g/dL, for children & pregnant & lactating women. For the rest of the population a maximum permissible level of lead in blood of 25  g/dL was established. There are no Mexican regulations for lead concentration in soil. EPA established a recommended concentration of lead of 400  g/g for residential use.

11 In 2002, INE & UAZ developed a study titled: DETERMINATION OF LEAD IN BLOOD OF CHILDREN & PREGNANT WOMEN IN VETAGRANDE, ZACATECAS Blood sampling: 30 children > 15 years 13 pregnant women Analysis: Flame Atomic Absorption Spectrometry (FLAAS). Results: Lead mean concentration in blood of children: 15.7  7.1 mg/dL Lead mean concentration in blood of pregnant women: 11.2  8.5 mg/dL

12 OBJECTIVES II To identify the health and environmental risk by sampling the houses indoors and throughout the natural floodlands within the town, as well as a risk characterization to identify bioavailability and exposition routes (using data from blood levels of lead). With this information, strategies are to be proposed to reduce environmental impact in the town. I INTRODUCTION II OBJECTIVE III MATERIALS & METHODS IV RESULTS V CONCLUSIONS RECOMMENDATIONS VI

13 MATERIALS & METHODS III Soil sampling: 89 sites were sampled within the town at 2.5 cm depth. Analysis was developed by X-Ray Dispersive Energy Spectrometry and were validated by Atomic Absorption Spectrometry. Quality control was developed by using certified standards (NIST & NBS). Number of samples was calculated by assuming that: Infinite number of possible samples. 50% of samples with higher concentration than 400 µg/g. 95% confidence. With this, the number of samples was calculated: 73 samples. I INTRODUCTION II OBJECTIVE III MATERIALS & METHODS IV RESULTS V CONCLUSIONS RECOMMENDATIONS VI

14 RESULTS IV I INTRODUCTION II OBJECTIVE III MATERIALS & METHODS IV RESULTS V CONCLUSIONS RECOMMENDATIONS VI

15 CONCENTRATION OF LEAD IN SOIL

16 Lead concentration ranges from 8 to 7730 µg/g. Mean concentration is 1397 ± 86 µg/g. % of total number of samples Range (µg/g)Mean (µg/g) ± ± ± ± ± ± % of samples were taken at the kinder garden & a mean concentration of 1901 µg/g was found.

17 gstat: Win32/MinGW version (12 March 2003), Copyright (C) 1992, 2003 Edzer J. Pebesma

18 CONCENTRATION OF LEAD IN BLOOD

19 Vetagrande, Zacatecas Category II ( μg/dL) Category III ( μg/dL) Category IV ( μg/dL) Kinder Museo Comunitario Presidencia

20 CONCLUSIONS V I INTRODUCTION II OBJECTIVE III MATERIALS & METHODS IV RESULTS V CONCLUSIONS RECOMMENDATIONS VI

21 Lead in soil 1. According to this study, lead concentration in soil ranges from 8.0 to 7730 ( µ g/g) & a mean concentration of 1397 ± 86 µg/g which is higher than the recommended concentration for residential soil according to EPA (400 µ g/g). This rises a potential risk for the population of the town while no speciation has been developed in the site. 2. Soil pollution can be associated to ancient mining activities, and no clear relationship is observed to current mining activities. 3. Several cases for high lead levels in blood were identified but no correlation was identified between lead in soil vs lead in blood. This can be related to different factors such as alimentation, drinking water pollution or bioavailability of contaminants in soil.

22 RECOMMENDATIONS VI I INTRODUCTION II OBJECTIVE III MATERIALS & METHODS IV RESULTS V CONCLUSIONS RECOMMENDATIONS VI

23 Health  Improve dietetics & nutritional habits within the population such as:  Glazed pottery usage.  Ingestion of dirt by hand-mouth mechanism.  Personal hygiene.  Consumption of food products that reduce assimilation of lead.  Establishment of a monitoring strategy of lead levels in blood for pregnant women & children.

24 Environment  Identify other routes of entry to the organism such as respiratory, ingestion of contaminated water, consumption of contaminated crops &/or meat.  Improve reforestation in the zone with endemic species to avoid generation of dusts.  Covering of the tailings with gravel or other materials to avoid spreading of such materials.  Improve urbanization in the town by paving the streets, paving the houses indoors & schoolyards, avoid contact with tailings deposited in the nearby.  Complete the study by analyzing the chemical species of lead in the contaminated area to identify the bioavailability of this contaminants to quantify the health risks & further remediation activities.

25 Thank you for your attention!


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