Date of Award


Degree Type


Degree Name

Doctor of Philosophy



Major Professor

Maureen Groer

Committee Members

Johnnie Mozingo, Mitzi Davis, Patricia Droppleman, Donald Creasia


The widespread use of pesticides by farmers, pest control operators and even the general public can pose significant risks to children's health. One particular pesticide, chlorpyrifos, was the most widely used pesticide in the United States with total use estimated at approximately 30 million pounds per year. Young children and the developing fetus are far more susceptible to the effects of pesticide exposure as a result of unusual exposure patterns and developmental immaturities. Transplacental transfer and lactational exposure are the pathways exclusive to the developing fetus and infant. Chlorpyrifos exposure is of special concern in this population because of its potential for disruption of normal brain function and cognitive development.

The purpose of this study was to determine the concentration of chlorpyrifos in three different biological specimens: breast milk, plasma, and saliva. The research method employed for this study was a secondary analysis of existing samples collected for the purposes of a prior study. Based on specimen availability, there were a total of 26 subjects each for the lactating group and the non-lactating group. The lactation group had 26 matched breast milk, plasma and saliva samples and the non-lactation group had 26 matched plasma and saliva samples. The biological specimens were tested in the laboratory using an assay specific to chlorpyrifos. The Chlorpyrifos RaPID Assay was developed by Strategic Diagnostics, Inc and had a detection limit of 0.1 ng/ml (ppb) and a linear range of 0.22 to 3.0 ng/ml (ppb).

Overall, for the lactation group, 25/26 samples were positive for chlorpyrifos with milk concentrations significantly higher than plasma or salivary concentrations. 19126 plasma samples were positive and 10/26 saliva samples were positive for chlorpyrifos. For the non-lactation group, 23/26 plasma samples were positive for chlorpyrifos and 16/26 saliva samples were positive. In addition, the plasma chlorpyrifos concentrations were significantly higher than salivary concentrations in the non-lactation group. Comparing the two groups, salivary chlorpyrifos concentrations were significantly higher in the lactation group.

There is mounting evidence of pesticide contamination in the breast milk of lactating women. This study has contributed to this knowledge by documenting chlorpyrifos concentrations in breast milk, plasma, and saliva of lactating and non-lactating mothers. However, further research needs to be done to determine what these chemicals are doing to our children.

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