7166
Given the present study ' s results , the particle size , the product composition , i . e . the crystalline structure , and the accumulation of nTiO ( 2 ) at the bottom of the test vessel - the latter is relevant for a semi - static test design - may be suggested as factors potentially triggering differences in nTiO ( 2 ) toxicity to D . magna .
 nTiO ( 2 ), nTiO ( 2 )
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 nTiO ( 2 ), nTiO ( 2 )