Table 3.

Cadmium (Cd) and Arsenic (As) exposure–responses for lung cancer using alternate model specifications for cadmium or arsenic alone and with constrained arsenic effect

Exposure metric, f(X)	intercept	â2	SMR0(exp(â0))	RR*	lrt: χ2 (1 df)†	p Value†
A: Cadmium or arsenic alone (lag = 5 years) model: SMR = [exp(a0+a1Ind(His))][1+a2f(X)]
cumCd‡	−0.205	0.211	0.82	3.1	10.2	0.0014
ln[cumCd+1]	−0.907	2.333	0.40	6.6	10.1	0.0015
sqrt(cumCd)	−1.375	3.062	0.25	10.7	10.9	0.0010
cumAs	−0.0046	1.218	0.99	13.2	9.18	0.0024
ln[cumAs+1]	−0.049	2.099	0.99	6.0	7.75	0.0054
sqrt(cumAs)	−0.296	2.060	0.74	7.5	7.05	0.0079
B: Cadmium with constrained arsenic effect (lag = 5 years (Cd), 0 year (As))§: SMR = [exp(a0+a1Ind(His))][1+a2f(Cd)+0.5495(cumAs)0.35]
cumCd	−0.368	0.215	0.69	3.2	6.3	0.012
ln[cumCd+1]	−1.028	2.476	0.36	5.9	6.2	0.013
sqrt(cumCd)	−1.562	3.632	0.21	11.5	7.0	0.008
durCd¶	−0.376	0.157	0.69	2.6	6.3	0.012

^*RR, ratio of SMRs, predicted at 10.0 mg-year/m³; for duration: predicted for 10 years.

^†p Value based on likelihood ratio test.

^‡cumCd and cumAs: cumulative exposures, in mg-year/m³.

^§Constrained As effect derived in table 4.

^¶durCd: duration of Cd exposure, lagged 5 years.

SMRs, standardised mortality ratios.