On a quarter acre lot, about half of the area would be grass and shrubs and would be treated. The number of ounces of pesticide applied to a yard would depend on the concentration of the pesticide in the formulation, but when applied at the above rate, a square yard of turf or other surface would have maximum pesticide residues of 0.0033 ounces. However, a misapplication or overdose could result in health concerns. Incidental ingestion, inhalation, or skin contact with the diluted spray is not expected to result in harm. One should avoid direct contact with the eyes or prolonged skin exposure.
Skin contact is the most likely route of exposure.
The first effects of airborne OP overexposure would be breathing and eye symptoms. Although unlikely to occur, cholinesterase inhibition from OP exposure is possible. Cholinesterase inhibition, a disruption of normal nervous system function, is characterized by symptoms such as headache, nausea, and dizziness. An individual can have a cholinesterase level check done by a physician to confirm exposure or toxicity. There is no evidence of chlorpyrifos causing birth defects, reproductive problems, nerve damage, or cancer.