Trichloroethylene uptake by apple and peach trees and transfer to fruit

A greenhouse study was conducted to quantify C-14-trichloroethylene (TCE) uptake and transfer into the edible fruit of apple and peach trees. Trees were subsurface irrigated with solutions of C-14 [TCE] that bracketed groundwater concentrations (5 and 500 mu g/L) found in residential areas surrounding Hill Air Force Base, UT, where trace amounts of TCE had been found in several fruits during a preliminary field survey. Nondosed control trees were grown within the canopy of the dosed trees and in a separate greenhouse. Tissue samples were analyzed for C-14 and TCE using combustion/liquid scintillation counting (LSC) and headspace/gas chromatography/mass spectrometry (HS/GC/MS). Tissue was also extracted and analyzed by GC/MS for dichloroacetic acid ( DCAA), trichloroacetic acid (TCAA), and trichloroethanol (TCEt), three specific TCE metabolites that have been previously identified in laboratory and field studies. No C-14 was detected in the nonexposed control trees. Exposed trees contained levels of C-14 that were proportional to the exposure concentration. C-14 concentrations were greatest in leaves followed by branches and fruits. At the end of the study, TCE was detected only in roots implying that the C-14 in the leaves, branches, and fruit was associated with unidentified nonvolatile TCE transformation products and/or is nonextractable. However, TCAA and DCAA were positively identified only in leaves collected during the first year from an apple tree exposed to the high dose treatment. Additional data for other chemicals and fruit trees are needed to better understand the potential transfer of organic compounds to edible fruit.