Table 4.

Associations of UNGD with negative control outcomes.

UNGD quartile	Adjusted odds ratios (95% confidence intervals)
	Ear pain yes (n = 422) vs. no (n = 3,917)	Bad breath yes (n = 846) vs. no (n = 2,628)	Cold/flu symptoms yes (n = 307) vs. no (n = 2,442)
1	1.00 (reference)	1.00 (reference)	1.00 (reference)
2	0.92 (0.58, 1.44)	0.87 (0.61, 1.22)	1.04 (0.58, 1.84)
3	0.53 (0.32, 0.87)	1.12 (0.80, 1.57)	1.15 (0.66, 2.00)
4	1.16 (0.74, 1.83)	0.95 (0.67, 1.35)	1.14 (0.64, 2.01)
UNGD, unconventional natural gas development. Individuals having the symptom at least “most of the time” in the past 3 months were compared with those having the symptom “never” in the past 3 months. All models included sampling and response weights, and the highest weight was truncated to the value of the second-highest weight. Models included the following covariates: sex, race/ethnicity (white non-Hispanic vs. other), centered age (linear and quadratic terms), Medical Assistance (never vs. ever), and smoking status (never vs. current and former). UNGD activity was averaged over the 90 days before the survey.