. Author manuscript; available in PMC: 2016 Apr 4.

Published in final edited form as: J Occup Environ Hyg. 2015;12(7):458–468. doi: 10.1080/15459624.2014.989358

Table III. Probability of Reporting Exposure According to Work-related Factors.

Work-related Factors	Skin Contact with Oil and Diesel				Oil Vapor from Shaker and Other Mud Cleaning				Exhaust Fumes				Vapor from Mixing Chemicals Used for Drilling

	No. of Persons	No. of Exposed	RR^A	95% CI P-value	No. of Persons	No. of Exposed	RR^A	95% CI P-value	No. of Persons	No. of Exposed	RR^A	95% CI P-value	No. of Persons	No. of Exposed	RR^A	95% CI P-value
Main activity
Catering	4348	293	1.00	Ref.	4362	156	1.00	Ref.	4373	156	1.00	Ref.	4354	59	1.00	Ref.
Production	1939	652	4.14	3.57-4.80	1930	319	3.51	2.84-4.35	1931	176	2.04	1.60-2.60	1928	40	1.43	0.91-2.25
Drilling	3724	2035	6.69	5.86-7.64	3727	1877	10.10	8.42-12	3703	725	3.95	3.25-4.81	3721	1314	16.42	12-22
Maintenance	12,538	3957	4.52	3.97-5.15	12,455	1901	4.08	3.40-4.89	12,472	1665	3.64	3.03-4.38	12,420	687	4.04	2.97-5.51
Miscellaneous	4202	1167	4.27	3.72-4.90	4168	529	3.31	2.71-4.05	4191	493	3.08	2.51-3.79	4192	213	3.47	2.47-4.87
Year left position
1967–1979	471	160	0.90	0.79-1.02	470	117	0.93	0.80-1.09	468	75	1.09	0.87-1.37	469	98	1.50	1.26-1.79
1980–1989	3062	954	1.02	0.97-1.08	3050	653	1.14	1.06-1.23	3043	416	1.11	1.00-1.23	3053	413	1.56	1.42-1.72
1990–1999	20,089	6176	1.00	Ref.	20,032	3515	1.00	Ref.	20,043	2368	1.00	Ref.	19,984	1542	1.00	Ref.
Continuous^B		1.002		0.292			0.994	0.007			0.994	0.096			0.971	<0.001
Supervisor/manager
No	16,040	5020	1.00	Ref.	15,984	3000	1.00	Ref.	15,989	1866	1.00	Ref.	15,962	1367	1.00	Ref.
Yes	10,583	3045	0.97	0.93-1.01	10,551	1765	0.91	0.86-0.97	10,561	1340	1.20	1.12-1.30	10,528	941	1.06	0.97-1.15
Type of company
Operating	9147	2417	1.00	Ref.	9111	1241	1.00	Ref.	9118	874	1.00	Ref.	9106	400	1.00	Ref.
Contractor	17,033	5516	1.01	0.96-1.06	16,992	3446	1.10	1.03-1.18	16,989	2266	1.08	0.99-1.18	16,947	1869	1.44	1.28-1.62
Type of installation
Stationary	19,159	5281	1.00	Ref.	19,109	2935	1.00	Ref.	19,116	1958	1.00	Ref.	19,068	1168	1.00	Ref.
Movable	6604	2438	1.20	1.15-1.26	6580	1636	1.20	1.13-1.27	6581	1091	1.33	1.23-1.45	6574	1034	1.47	1.35-1.60
Work schedule
Daytime	13,775	2873	1.00	Ref.	13,746	1192	1.00	Ref.	13,753	1014	1.00	Ref.	13,722	332	1.00	Ref.
Night time	1030	278	1.06	0.95-1.20	1029	181	1.36	1.17-1.59	1027	119	1.43	1.17-1.75	1031	90	1.86	1.46-2.37
Shiftwork	10,970	4587	1.57	1.50-1.65	10,926	3150	2.11	1.96-2.28	10,926	1885	2.03	1.85-2.22	10,911	1770	3.05	2.65-3.50
Educational level
Compulsory	3181	1048	1.00	Ref.	704	3163	1.00	Ref.	3160	486	1.00	Ref.	3138	401	1.00	Ref.
Vocational training	10,600	3610	1.01	0.95-1.08	1964	10,545	0.85	0.79-0.93	10,564	1450	0.87	0.78-0.97	10,527	954	0.82	0.73-0.92
Upper secondary	6672	2124	0.99	0.93-1.06	1129	6655	0.81	0.75-0.89	6651	770	0.82	0.73-0.92	6646	520	0.72	0.63-0.82
University/college	6339	1324	0.65	0.60-0.70	992	6342	0.73	0.67-0.80	6344	525	0.57	0.49-0.65	6348	444	0.56	0.49-0.64

Notes: RR = relative risk; CI = confidence interval; Ref. = reference category.

For each exposure, all factors were included in the regression model simultaneously.

Year left position included as continuous variable.