Table 1

Association between smoking, environmental and occupational pollution, and lung cancer in the Northern Province, South Africa

Cases (n) Cases (%) Controls (n) Controls (%) Total (n) OR 95% CI
Males
Smoking status1-150
Never34(11.8)103(56.3)1371.0Referent
 Ex-smoker17(5.9)20(10.9)372.21.0–4.6
 Current237(82.2)60(32.7)29710.76.6–17.3
<15 g/day135(46.8)40(21.9)1759.85.9–16.4
⩾15 g/day96(33.3)18(9.8)11412.06.5–22.3
 Not specified6(2.1)2(1.1)8
 Total288(100.0)183(100.0)471
 χ2(p trend)92.8(0.0001)
Industry1-151
Not dusty2243651.0Referent
 Dusty266(92.3)140(76.5)4063.21.8–5.8
 χ2 (p trend)15.1(0.0001)
Wood/coal in house1-152
No2825531.0Referent
 Yes260(90.3)158(86.3)4181.90.9–3.3
 χ2 (p trend)2.3(0.1)
Asbestos exposure current residence1-153
None218(78.9)161(88.0)3791.0Referent
 Moderate38(13.8)11(6.0)492.11.0–4.4
 Heavy10(3.6)3(1.6)192.80.7–10.4
 Not specified10(3.6)8(4.4)185.7(0.02)
 χ2 (p trend)5.7(0.2)
Asbestos exposure at birth1-153
None173(60.1)134(73.2)3071.0Referent
 Moderate35(12.1)9(4.9)442.91.2–6.7
 Heavy8(2.8)2(1.1)103.10.4–21.4
 Not specified72(25.0)38(20.1)110
 χ2(p trend)7.5(0.006)
Women
Smoking1-150
Never32(53.3)190(96.5)2221.0Referent
 Ex-smoker4(6.7)2(1.0)65.81.3–25.8
 Current24(4.0)5(2.5)295.51-154 2.6–11.3
<15 g/day15(25.0)4(2.0)19
⩾15 g/day8(13.3)0(0.0)8
 Not specified1(1.7)1(0.5)2
 Total60(100)197(100)257
 χ2(p trend)31.3(0.0001)
Industry1-151
Not dusty1737541.0Referent
 Dusty43(71.6)160(81.2)2030.50.3–1.1
 χ2 (p trend)2.6(0.1)
Wood/coal fuel1-152
No941501.0Referent
 Yes51(85.0)156(79.2)2071.40.6–3.2
 χ2 (p trend)0.5(0.5)
Asbestos exposure current residence1-153
None45(75.0)180(91.4)2251.0Referent
 Moderate4(6.7)11(5.6)151.10.3–3.9
 Heavy6(10.0)4(2.0)105.41.3–22.5
 Not specified5(8.3)2(1.0)7
 χ2(p trend)5.2(0.02)
Asbestos exposure at birth1-153
None36(60.0)162(82.2)1981.0Referent
 Moderate2(3.3)8(4.1)10
 Heavy3(5.0)0(0.0)32.41-160 0.7–7.9
 Not specified19(31.7)27(13.7)46
 χ2(p trend)1.9(0.2)
  • 1-150 Adjusted for age (<55, ⩾55 years), dusty occupation, and exposure to asbestos at birth.

  • 1-151 Adjusted for age (<55, ⩾55 years), smoking (never-smoker, ex-smoker, current specified), and asbestos exposure at birth.

  • 1-152 Adjusted for smoking (never-smoker, ex-smoker, current specified), dusty industry, and residential asbestos exposure.

  • 1-153 Adjusted for smoking (never-smoker, ex-smoker, current specified), and dusty industry.

  • 1-154 Data for current unspecified, light and heavy female smokers were combined.

  • 1-160 Data for females born in moderate and heavy asbestos districts were combined.