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. Author manuscript; available in PMC: 2016 Apr 26.
Published in final edited form as: Cancer Causes Control. 2014 Aug 5;25(10):1351–1367. doi: 10.1007/s10552-014-0441-z

Table 1.

Details of occupational exposure assessment in the 13 studies in the CLIC pooled analyses of parental occupational paint exposure and the risk of leukemia in the offspring

Country,
Study
(years
of
case
accrual)		 Method
of
occupational
assessment		 Case Control Time
period(s)
of
interest1,		 Scope
of
assessment		 Final
exposure
variable2 		Prevalence
of
‘High
likelihood
of
paint
exposure’
amongst
controls		 Source
of
conversion
tool
to
other
Occupational
Classifications
(where
applicable)
Source Participationc Nd Source
&
type
of
matching		 Participation3 N4 Mothers Fathers
1. Use of an Occupational Classification System
France, ADELE (1993–1999) ISCO 1988 Hospitals 95% ALL: 240
AML: 36		 Hospitals (same as cases)

Frequency matched		 99% 288 Extracted from work history (start & end year of each job)

  1. Main year before conception (defined as the year of the mid point of the year before conception)

  2. Main year of pregnancy (defined as the year of the midpoint of the pregnancy)

 All jobs held in time periods 4 level
1. ‘High likelihood of paint exposure’
2. ‘Moderate likelihood of exposure’
3. ‘Limited likelihood of exposure’
4 = ‘No or minimal likelihood of paint exposure’		 0.0 3.0 Correspondence Table ISCO 08 to ISCO 88 [20]
Greece, NARECHEM (1993–1994) ISCO 1988 Nationwide hospital cancer registry 100% ALL; 140
AML: 13		 Hospital

Individual matched		 96% 300

  1. One year before birth

  2. During pregnancy

 All jobs held in time periods As above 0.0 1.3 Correspondence Table ISCO 08 to ISCO 88 [20]
France ESCALE (2003–2004) ISCO 1968 Population-based cancer registry (nationwide) 91% ALL: 648
AML: 101		 Population quotas by age, sex, region (nationwide)
Frequency matched		 71% 1681

  1. During pregnancy5

 Main job in time period As above 0.0 1.2 Correspondence Table ISCO 68 to ISCO 88 [21]
Greece, NARECHEM (1996–2010) ISCO 1968 Nationwide hospital cancer registry 83% ALL: 964
AML: 113		 Hospital

Individual matched		 96% 1085

  1. One year before birth

  2. During pregnancy

 All jobs held in time periods As above 0.0 1.1 Correspondence Table ISCO 68 to ISCO 88 [21]
Italy, SETIL (1998–2001) ISCO 1968 Nationwide clinical database 91% ALL: 601
AML: 32		 Population-based National Health Service Registry 70% 1044 Extracted from work history (start & end year of each job)

  1. Main year before conception (defined as the year of the mid point of the year before conception)

  2. Main year of pregnancy (defined as the year of the midpoint of the pregnancy)

 All jobs held in time periods As above 0.4 1.0 Correspondence Table ISCO 68 to ISCO 88 [21]
Germany, GCCR (1988–1994) Germany, Bundesgentur fur Abeit Wirtschaftsklasse 1988 Population-based cancer registry (nationwide) 82% ALL: 751
AML: 130		 Population-based registry (community based but complete nationwide coverage)

Individual matched		 71% 2458

  1. Conception

  2. During pregnancy

 Main job in time periods As above <0.1 1.5 Correspondence Table to ISCO 88 obtained from Federal Statistical Office, Germany [22]
UK, UKCCS (1991–1996) UK, Standard Occupational Classification 1990 Population-based tailored referral systems 93% ALL: 1461
AML: 248		 GP registries (nationwide)

Individual matched		 64% 3448

  1. Around conception

  2. During pregnancy

 All jobs held in time periods As above 0.0 1.7 Correspondence Table to ISCO 88 obtained from Office for National Statistics, UK [23]
US, NCCLS (1995–2008) US, Census Occupational Classification Codes, 1990 Hospitals 86% ALL: 840
AML: 145		 Birth registry (statewide)

Individual matched		 68% 1226 Extracted from work history (start and end month, year of each job)

  1. Year before conception

  2. During pregnancy

 All jobs held in time periods As above 0.1 1.2 Correspondence Tables obtained from the National Crosswalk Center [24] between 1990 Census to 2000 Census codes and 2000 Census codes to ISCO 88
US, COG-E15 (1989–1993) US, Department of Lab or Dictionary of Occupational Titles (4th ed., rev. 1991) Children’s Cancer Group clinical trials 87% ALL: 1914 RDD

Individual matched		 70% 1987 Extracted from work history (start and end month, year of each job)

  1. Year before conception

  2. During pregnancy

 All jobs held in time periods As above 0.2 1.4 Correspondence Tables obtained from the National Crosswalk Center [24] between DOT to 2000 Census codes and 2000 Census codes to ISCO 88
2. Paint exposure already assigned
Australia, Aus-ALL [11] (2003–2007) Answers to initial structured questionnaire and follow-up job specific interview reviewed by expert14 Hospitals (nationwide) 75% ALL: 389 RDD

Frequency matched		 64 % of agreed controls 876

  1. One year before birth

 All jobs held in time period 3 level:
1 = medium/high exposure
2 = low expo sure
4 = not exposed		 0.5 7.5
Canada, Quebec [16] (1980–2000) Answers to initial structured interview and follow-up job specific questions reviewed by expert12,16 Hospitals (province wide) 93% ALL: 790 Health Insurance file population-based registry (province-wide.)
Individual matched		 86% 790

  1. Two years before conception

  2. During pregnancy

 All jobs held in time periods 3 level:
1 = greater exposure
2= some exposure
4 = not exposed		 0.8 4.6
New Zealand, NZCCS (1990–1993) Exposure assignment based on detailed questionnaire and interview about paint exposures in each job Regis try (nationwide) 92% ALL: 97
AML: 22		 Birth registry (nation wide)

Individual matched		 69% 303

  1. Two years before birth

    (No maternal exposure data available)

 All jobs held in time periods 2 level:
1 = exposed
4 = not exposed		 NA 11.4
3. Paint exposure data collected, but exposure not assigned
US, COG-E14 (1988–1993) Detailed questionnaire about each type of paint use in each job Children’s Cancer Group clinical trials 76% AML: 517 RDD

Individual matched		 72% 610 Extracted from work history (start and end month, year of each job)

  1. Year before conception

  2. During pregnancy

 All jobs held in time periods 4 level: Tertiles of exposure6
1 = ‘High’
2 = ‘Medium’
3 = ‘Low’
4 = unexposed		 0.8 6.2
1

The time periods of interest were 1. Around conception for the father and 2. During pregnancy for the mother.

2

In the final pooling process, a 4 level variable was used, but levels 2 and or 3 were empty for studies with less than 4 categories.

3

Participation fractions are based on information available from published studies or obtained directly from study personnel. Definition of the participation fraction may vary across studies.

4

Occupational histories were available for more than 90% of parents. The numbers of mothers and fathers with occupational histories are in Supplementary Table 5.

5

In France ESCALE, paternal exposure during pregnancy was used as a proxy for paternal exposure at conception as these data were not available.

6

Based on tertiles of the total time any paint was in the air the subject or on the skin/clothing during time period among exposed control mothers and fathers.

ISCO: International Standard Classification for Occupation

RDD: random digit dialing