Table 2.

Correlation between chemical or physical characteristics of MWFs and microbial biome

Explanatory variable	Predicted variables
	Samples with GNR		Samples with GPR		Sterile samples
	%a	P value	%	P value	%	P value
Nature of aqueous fluid
Emulsion	71	=0.04			11	=0.03
Semisynthetic fluid	59				22
Synthetic fluid	43				33
Nature of oil base (emulsions)
Mineral origin	61.5	=0.03	36.5	=0.05
Vegetable origin	88.5		15.4
Metals worked
Chrome	87	≤0.001	8.7	≤0.001
No chrome	56		34.5
Nickel	88	≤0.001	9.3	=0.002
No nickel	57		33.6
Ferrous metal	71	=0.01
No ferrous metal	49
Filamentous fungi
Presence	84	=0.01
Absence	57

^aPercentage of samples matching each category.