Such changes may be the result of {TAIL ~ exposure} of the cells to {HEAD ~ environmental toxins} 
Such changes may be the result of { TAIL ~ exposure } of the cells to { HEAD ~ environmental toxins }
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD