Table 1.
Selected characteristics including occupational exposure assessment of the 13 studies in the CLIC pooled analyses of parental occupational pesticide 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 interesta | Scope of assessment |
Final exposure variableb |
Prevalence of
‘High likelihood of pesticide exposure’ amongst controls |
Source of conversion tool to other Occupational Classifications (where applicable) |
|||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Source | Participationc | Nd | Source | Participationc | Nd | Mothers | Fathers | ||||||
| 1. Use of an Occupational Classification
System |
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| France, ADELE (1993–1999) | ISCO 1988 | Hospitals | 95% | ALL: 240 AML: 36 |
Hospitals (same as cases) | 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 pesticide exposure’ 2. ‘Moderate likelihood of exposure’ 3. ‘Limited likelihood of exposure’ 4 = ‘No or minimal likelihood of pesticide exposure’ |
0.4 | 1.7 | Correspondence Table ISCO 08 to ISCO 8819 |
| Greece, NARECHEM (1993–1994) | ISCO 1988 | Nationwide hospital cancer registry | 100% | ALL; 140 AML: 13 |
Hospital | 96% | 300 | 1.One year before birth 2.During pregnancy |
All jobs held in time periods | As above | 2.9 | 9.8 | Correspondence Table ISCO 08 to ISCO 8819 |
| France ESCALE (2003–2004) | ISCO 1968 | Population-based cancer registry (nationwide) | 91% | ALL: 648 AML: 101 |
Population quotas by age, sex, region (nationwide) | 71% | 1681 | 1.During pregnancye | Main job in time period | As above | 0.8 | 4.3 | Correspondence Table ISCO 68 to ISCO 8820 |
| Greece, NARECHEM (1996–2010) | ISCO 1968 | Nationwide hospital cancer registry | 83% | ALL: 964 AML: 113 |
Hospital | 96% | 1085 | 1. One year before birth 2. During pregnancy |
All jobs held in time periods | As above | 1.1 | 3.0 | Correspondence Table ISCO 68 to ISCO 8820 |
| 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) | 71% | 2458 | 1. Conception 2. During pregnancy |
Main job in time periods | As above | 1.2 | 3.0 | Correspondence Table to ISCO 88 obtained from Federal Statistical Office, Germany21 |
| UK, UKCCS (1991–1996) | UK, Standard Occupational Classification 1990 | Population-based tailored referral systems | 93% | ALL: 1461 AML: 248 |
GP registries (nationwide) | 64% | 3448 | 1. Around conception 2. During pregnancy |
All jobs held in time periods | As above | 0.3 | 2.4 | Correspondence Table to ISCO 88 obtained from Office for National Statistics, UK22 |
| US, NCCLS (1995–2008) | US, Census Occupational Classification Codes,1990 |
Hospitals | 86% | ALL: 840 AML: 145 |
Birth registry (state wide) | 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 | 2.0 | 8.3 | Correspondence Tables obtained from the National Crosswalk Center23 between 1990 Census to 2000 Census codes and 2000 Census codes to ISCO 88 |
| US, COG-E15 (1989–1993) | US, Department of Labor Dictionary of Occupational Titles (4th ed., rev. 1991) | Children’s Cancer Group clinical trials | 87% | ALL: 1914 | RDD | 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 | 1.1 | 4.2 | Correspondence Tables obtained from the National Crosswalk Center23 between DOT to 2000 Census codes and 2000 Census codes to ISCO 88 |
| 2. Pesticide exposure already
assigned |
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| Australia, Aus-ALL (2003–2007) | Answers to initial structured questionnaire and follow-up job specific interview reviewed by expert14 | Hospitals (nationwide) | 75% | ALL: 389 | RDD | 64% of agreed controls | 876 | 1. One year before birth | All jobs held in time period | 3 level: 1 = medium/high exposure 2 = low exposure 4 = not exposed |
0.2 | 5.5 | |
| Canada, Quebec (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) | 86% | 790 | 1. Two years before conception 2. During pregnancy |
All jobs held in time periods | 2 level: 1 = exposed 4 = not exposed |
4.4 | 7.9 | |
| Italy, SETIL (1998–2001) | Answers to initial structured interview and follow-up job specific questions reviewed by experts24 (restricted to agricultural pesticides) | Nationwide clinical database | 91% | ALL: 601 AML: 32 |
Population-based National Health Service Registry | 69% | 1044 | 1. One year before conception 2. During pregnancy |
All jobs held in time periods | 2 level: 1 = exposed 4 = not exposed |
0.4 | 1.9 | |
| New Zealand, NZCCS (1990–1993) | Exposure assignment based on detailed questionnaire and interview about pesticide exposures in each job | Registry (nationwide) | 92% | ALL: 97 AML: 22 |
Birth registry (nationwide) | 69% | 303 | 1. Two years before birth 2. During pregnancy |
All jobs held in time periods | 2 level: 1 = exposed 4 = not exposed |
1.3 | 18.0 | |
| 3. Pesticide exposure data collected, but
exposure not assigned |
|||||||||||||
| US, COG-E14 (1988–1993) | Detailed questionnaire about each type of pesticide use in each job | Children’s Cancer Group clinical trials | 76% | AML: 517 | RDD | 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 exposuref 1 = ‘High’ 2 = ‘Medium’ 3 = ‘Low’ 4 = unexposed |
0.3 | 5.2 | |
a
The time periods of interest were 1. Around conception for the father and 2. During pregnancy for the mother.
b
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.
c
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.
d
Occupational histories were available for more than 90% of parents. The numbers of mothers and fathers with occupational histories are in Supplementary Table 2.
e
In France ESCALE, paternal exposure during pregnancy was used as a proxy for paternal exposure at conception as these data were not available.
f
Based on tertiles of the total time any pesticide 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