. Author manuscript; available in PMC: 2015 Nov 4.

Published in final edited form as: Occup Environ Med. 2012 Jan 22;69(5):303–309. doi: 10.1136/oemed-2011-100149

Table 2.

Models of cadmium and arsenic exposure response for lung cancer using traditional cumulative exposures (mg-year/m³, 5-year lag)

Model	Effect^*	â_i	SMR₀^†(exp(â₀))	RR^‡	lrt: χ² (df)^§	p Value^§
1	Intercept (non-Hispanic)	−0.205	0.81
	Hispanic (0, 1)	−1.130	0.26 ^¶	0.32		0.007
	Cumulative cadmium	0.211		3.11	10.2 (1)	0.0014
2	Intercept (non-Hispanic)	−0.005	0.98
	Hispanic (0, 1)	−1.054	0.35	0.35		0.012
	Cumulative arsenic	1.218		13.2	9.2 (1)	0.0024
3	Intercept (non-Hispanic)	−0.190	0.83
	Hispanic (0, 1)	−1.098	0.27	0.33		0.009
	Cumulative cadmium	0.125		2.25	2.03 (1)	0.154
	Cumulative arsenic	0.766		8.66	1.00 (1)	0.317
					11.2 (2)^**	0.0037

Model: SMR=[exp(a₀ + a₁Ind(His))] × [1+a₂(cumCd)+a₃(cumAs)]; a₃=0 in model 1 and a₂=0 in model 2; His = Hispanic ethnicity.

^†

SMR₀, estimated SMR for unexposed.

^‡

RR, ratio of SMRs, predicted at 10.0 mg-year/m³.

^§

χ² to remove exposure term (likelihood ratio test, lrt) and associated p value; for Hispanic term, p value based on Wald statistic.

^¶

0.26 = 0.81×0.32 = exp(−0.205)×exp(−1.13).

^**

lrt for both exposure terms together.

SMRs, standardised mortality ratios.