Date of Award

2015-01-01

Degree Name

M.P.H.

Department

Public Health

Advisor(s)

Christina Sobin

Abstract

Background & Significance: Heavy metals have been identified as a child health hazard because children are highly vulnerable to the effects of exposure, which can be physical, cognitive, and behavioral. Levels of arsenic (As) greater than the EPA Maximum Contaminant Level (10μg/L) were identified in some household water samples in two rural west Texas communities located within 20 miles of the U.S.-Mexico border by a Health Impact Assessment conducted in 2013 (Hargrove, Juarez-Carillo, & Korc 2015). Whether home water samples predicted child blood As levels needed to be examined. Since lead (Pb) is another common heavy metal contaminant in the border region, Pb was also examined.

Aims and Objectives: The goals of this study were to measure blood As and Pb levels in children; measure As and Pb in childrenâ??s home water samples; and obtain parent-reported assessments of child behavior.

Hypotheses: H1): there is a linear relationship between arsenic in home water samples and child blood arsenic levels; H2): there is a linear relationship between lead in home water samples and child blood lead levels; H3): there is a linear relationship between child arsenic or lead levels and child behavior, as assessed by the child “Strengths and Difficulties Questionnaire” (Goodman & Goodman, 2012).

Methods: This was an observational study of 104 elementary school children ages 5 – 11 years, including 40 children from Community 1, whose families relied on water from domestic wells or privately owned wells made available to the public, and 64 children from Community 2, whose families relied on water from the municipal public water supply. Family demographics, child medical history, and child behavior assessments were collected from parents. Child As and Pb levels were determined from finger-stick blood samples analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Household water samples were collected following EPA guidelines and analyzed also by ICP-MS.

Results: Blood As mean values for children from both schools exceeded the reference value of 1.2μg/dL (Mayo Clinic, 2014). Generalized mixed model linear regression analysis showed child blood As level was predicted by As household level (F1/101= 4.71, p= 0.03), controlling for school as a random effect. Sex and age, and the sex by age interaction did not contribute significantly to the model. Models for Pb could not be conducted because most household water samples contained no detectable Pb. There was no association between children’s blood As levels and behavior, controlling for age, sex, and school as a random effect.

Conclusion: Regardless of household water source (groundwater from domestic wells or privately owned wells made available to the public in Community 1 or water from the public municipal system in Community 2) children had blood As levels above the acceptable limit (1.2 μg/dL). Household water As levels predicted a significant proportion of variance in child blood As levels. For every one unit increase of As in home water samples (μg/dL), child blood As level increased by 0.26 μg/dL. A finding that may suggest that the current EPA Maximum Contaminant Level for As in drinking water (10μg/L) is not low enough to expose children to As. At the same time, the remaining unexplained variance in the model suggested that other sources of exposure are also contributing to child blood As levels.

Recommendations: As blood levels in children from these two communities must be monitored, and the other possible sources of contamination, such as soil and air, must be tested. Concerns of parents and teachers regarding child As exposure must be addressed in ongoing interactions with the communities and education about nutrition must be provided to the communities.

Language

en

Provenance

Received from ProQuest

File Size

76 pages

File Format

application/pdf

Rights Holder

MIchelle Del Rio

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