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Table 3 Effects of farm childhood and adult farm work/exposure on the risk of asthma/rhinitis/allergic sensitization in adulthood: Studies from 2000

From: Respiratory diseases and allergy in farmers working with livestock: a EAACI position paper

References/country Populations (n)/design Farm childhood Adult exposure Asthma Rhinitis SPT Specific IgE Total IgE Remarks
OR (95% CI) unless otherwise stated
Lampi et al. [92]/Finland 2011 Prospective birth cohort study; atopy at age 31 1262+ vs 4247− Not done Dd asthma ever: 0.7 (0.5–1.0) Allergic rhinitis at age 31: 0.9 (0.7–1.03) Positive SPT: 0.7 (0.6–0.8) Not done Not done /
Omland et al. [8]/Denmark 2011 (SUS study) Nested case–control study (107 vs 102) 77+ vs 132 Swine farming (n = 94)
Dairy farming (n = 59)
New-onset asthma Farm childhood: 0.50 (0.2–0.98)
Exposure during FU: Swine 3.4 (1.6–7.0)
Dairy 2.5 (1.1–5.3)
Not done Atopy (positive SPT): not a risk factor for new-onset asthma Not done Not done /
Varraso et al. [149]/France 2012 54,018 female adults/13 years. follow-up Farmer parents
Place of birth
Bovine density score 0–3
Not done Farmer parents: childhood asthma 0.5 (0.4–0.7) adult-onset asthma 0.7 (0.6–0.8)
Rural birth: childhood asthma 0.8 (0.7–0.9) adult-onset asthma 0.9 (0.8–0.96)
Highest vs. lowest bovine density score: childhood asthma 0.7 (0.5–0.98) adult-onset asthma 0.8 (0.6–0.98)
Not done Not done Not done Not done Focus on asthma history and phenotype and on dietary factors
Effects on both persistent and adult-onset asthma
Elholm et al. [11]/Denmark 2013 (SUS study) 1166/follow-up at age 35 for new sensitization to common allergens 496+ vs 476− (of 1162) Farm work during follow-up (age 20–35) Not stated Not stated No-farm childhood 0.6 (0.3–1.3)
Farm childhood 0.4 (0.1–1.2)
No-farm childhood 0.2 (0.05–0.7)
Farm childhood: too few subjects
Not done /
Elholm et al. [42] Denmark 2018 (SUS study) 884 (of 1166) follow-up at age 35 for new onset sensitization      Farm Childhood OR = 0.5
Sensitisation to pollen during follow up vs sensitization in no-farm child
Farm Childhood OR = 0.5 Sensitisation to pollen during follow up vs sensitization in no-farm child Not done  
Elholm et al. Denmark 2018 (SUS study) 1116 (of 1166)/follow-up at age 35 for new sensitization to Lep D 558
558
Farm work during follow-up (age 20–35) Not done Not done Farm Childhood OR = 0.5
Sensitisation to endotoxin during follow up ass to less sensitization in no-farm child
Farm Childhood OR = 0.5
Sensitisation to endotoxin during follow up ass to less sensitization in no-farm child
Not done  
Kilpeläinen et al. [85]/Finland 2000 10,667 1st year university students/cross-sectional 1095+ vs 1243- Not done Farm childhood: dd asthma 0.7 (0.5–0.9) Farm childhood: dd rhinitis 0.6 (0.5–0.8) Not done Not done Not done /
Ernst &Cormier [86]/Canada 2000 1199 secondary school children from rural areas, age 12–19 years/cross-sectional 802+ vs 397− Not done Farm childhood: wheeze 0.7 (0.6–0.99)
dd asthma 0.7 (0.4–0.98)
Not done Farm childhood: 0.6 (0.5–0.8) Not done Not done Farm childhood: BHR 0.8 (0.6–0.9)
Leynaert et al. [87]/4 EU and NZ (ECRHS) 2001 6251 subjects 20–44 years of age/cross-sectional study in the general population 548+ vs 5703− Not done Farm childhood: current asthma 0.8 (0.5–1.39)
wheeze 1.1 (0.8–1.5)
Farm childhood: pollen-related nasal sx 0.8 (0.6–1.02)
animal/feather/dust-related sx 0.97 (0.8–1.2)
Not done Farm childhood: 0.8 (0.6–0.97)
cat sensitization 0.6 (0.4–0.96)
grass s. 0.7 (0.5–0.9)
hdm s. 0.8 (0.6–1.1)
Cladosporium s. 0.9 (0.4–1.9)
Not stated Between-country heterogeneity
Portengen et al. [88]/Denmark 2002 999 farming students age 19 years/cross-sectional 505+ vs 494− Farming vs non-farming Farm childhood: asthma 0.8 (0.5–1.3)
wheeze 0.7 (0.4–1.1)
Farmers: wheeze less often than controls (p < 0.05)
Farm childhood: rhino-conjunctivitis 0.7 (0.5–0.99) Farm childhood: 0.5 (0.4–0.8)
Farmers: + SPT lower than controls (p < 0.05)
Not stated Farm childhood: 0.7 (0.5–1.1) Farm childhood: BHR 0.6 (0.4–0.95)
Eduard et al. [104]/Norway 2004 1614 farmers/cross-sectional Not done JEM, farmers with livestock vs farmers without livestock Asthma: cattle farmers 1.8 (1.1–2.8)
pig farmers: 1.6 (1.0–2.5)
Non-atopic asthma: pig farmers 2.0 (1.2–3.3)
2 + livestock 1.9 (1.1–3.3)
Atopic asthma: 2 + livestock 0.3 (0.1–0.97)
Not done Not done Not stated Not done Atopic vs. non-atopic asthma
Radon et al. [102]/Germany 2004 3112 rural subjects, age 18–44 years/cross-sectional 1268+ vs 1807− Presently living on farm Presently living on a farm: atopic asthma sx 0.7 (0.4–1.4)
non-atopic asthma 0.9 (0.6–1.4)
Regular visits to stables started at age 4–6: atopic asthma sx 0.4 (0.2–0.95)
Presently living on a farm: nasal allergies 0.6 (0.4–0.9)
Regular visits to stables started at age 4–6: nasal allergies 0.4 (0.2–0.6)
Not done Not done Not done /
Koskela et al. [150]/Finland 2005 231 women living on a farm, 202 women not living on a farm/cross-sectional 119+ vs 314− Presently living on farm Not done Not done + SPT: living in a dairy farm 35%, not living on a dairy farm 37% (NS) Sensitization to pollens: living in a dairy farm 4.4%, not living on a dairy farm 17.3% (p = 0.01)
S. to cat: living in a dairy farm 3.5%, not living on a dairy farm 10.4% (p < 0.05)
Not done Not done Protection by living on a dairy farm only
Portengen et al. [151]/The Netherlands 2005 162 pig farmers/case- control study Not done Modelled airborne endotoxin Not done Not done + SPT: endotoxin exp. < 75 ng m−3 0.03 (0.0–0.3)
endotoxin exp. > 75 ng m−3 1.2 (0.4–3.6)
Endotoxin exposure: 0.9 (0.3–2.3) Endotoxin exposure: 1.2 (0.5–2.3) Endotoxin exposure associated with BHR in sensitized pig farmers: 17 (1.3–227)
Radon et al. [103]/Germany 2006 2678 rural adults, age 18–44 years/cross-sectional Only in childhood: 877+ 1118− Childhood and adulthood: 421+ 876−
Only in adulthood: 75+ vs 1043−
Not done Allergic rhinitis and farm animal exposure: only in childhood 0.7 (0.5–0.9)
In childhood and adulthood 0.2 (0.1–0.4)
Only in adulthood 1.0 (0.4–2.6)
Not done + specific IgE and farm animal exp: only in childhood 0.7 (0.5–0.9) in childhood and adulthood 0.4 (0.3–0.6)
Only in adulthood 2.4 (1.1–5.2)
Not done Adult protection = effect of self-selection?
Douwes et al. [89]/New Zealand 2007 4262 farmers vs 1314 non-farmers/cross-sectional 3081+ vs 2495− Not done Current and childhood exp.: asthma ever 0.6 (0.5–0.7)
Wheeze 0.6 (0.5–0.7)
Current exp. only: asthma ever 0.7 (0.6–0.8)
wheeze 0.8 (0.6–0.99)
Childhood exp. only: asthma ever 0.9 (0.6–1.2)
wheeze 1.01 (0.7–1.3)
Current farming exp.: self-reported nasal sx 0.97 (0.8–1.1)
Childhood exp. only: self-reported nasal sx 0.8 (0.7–0.9)
Not done Not done Not done /
Chen et al. [91]/Canada 2007 579 farmers/cross-sectional study in the general population Not done Grain or livestock farming (85% both) Dd asthma
OR = 0.8 (0.5–1.1)
Self-reported nasal sx OR = 0.95 (0.8–1.2) hdm, grass pollen, cat, Alternaria
0.7 (0.6–0.9)
Not done Not done /
Schulze et al. [152]/Germany 2007 1595, age 18–44 years/cross-sectional 677+ vs 918− Not done   Farmers: dd 0.7 (0.4–1.1) Farmers: allergic rhinitis, 0.5 (0.4–0.8) Farmers: + SPT 0.7 (0.6–0.9) Not done Dd asthma in sensitized farmers: 0.5 (0.3–1.0)
BHR in sensitized farmers: 0.8 (0.5–1.1)
Smit et al. [100]/The Netherlands 2007 593 organic farmers vs 1205 conventional farmers, mean age 44–45/cross-sectional 1370+ vs 428− 911 livestock only 629 crops only
258 livestock and crops
Livestock farmers 1.0 (0.5–2.2)
Livestock farmers with childhood farm exp.: 0.6 (0.4–1.2)
Livestock farmers 0,5 (0.3–0.9)
Livestock farmers with childhood farm exp.: 0.4 (0.3–0.7)
Not done Not done Not done No clear effect organic farming
Smit et al. [10]/The Netherlands 2008 877 farmers and agri-industry workers, mean age 40–46/cross-sectional 511+ vs 366− Endotoxin exposure (modelled) Farm childhood: dd 0.9 (0.3–2.8)
No farm childhood: dd 0.9 (0.4–2.3)
Endotoxin exp.: wheezing 1.4 (1.2–1.7)
dd 0.99 (0.5–2.0)
Farm childhood: self-reported 0.6 (0.4–0.9)
No farm childhood: self-reported 0.6 (0.4–0.8)
Endotoxin exp.: self-reported 0.6 (0.5–0.8)
    No effect modification by farm childhood
Eriksson et al. [153]/Sweden 2010 18,087 rural population/cross-sectional 2557+ vs 15,238– Urbanization Not done Raised on a farm: self-reported 0.8 (0.7–0.9) Not done Not done Not done /
Smit et al. [101]/The Netherlands 2010 427 farmers 193+ vs 234− Endotoxin exposure (modelled) Endotoxin exposure: wheezing 1.3 (1.01–1.7) Endotoxin exposure: self-reported 0.6 (0.4–0.7) Not done Endotoxin exp.: specific IgE to common allergens 0.7 (0.5–0.8) Endotoxin exposure: total IgE 0.9 (0.7–1.05) Effects on sensitization mainly in non-FC
Endotoxin exposure: BHR 1.5 (1.03–2.3)
Basinas et al. [7]/Denmark and The Netherlands 2012 3883 farmers, veterinary students and power plants workers/cross-sectional + (adjusted) JEM-estimated airborne endotoxin: four levels; reference ≤ 50 EU m−3 High vs low occup. endotoxin exposure: wheezing 1.7 (1.1–2.6) asthma 1.5 (1.1–2.1) High vs low occupational endotoxin exposure: hay fever 0.6 (0.4–0.9) High vs low occup. endotoxin exposure: positive SPT and/or IgE to pollen, hdm, and pets 0.7 (0.4–0.99)   Not done /
Galli et al. [93]/Italy 2015 78 Italian swine farmers vs 82 non-swine farmers/cross-sectional Not stated Swine farming vs non-swine farmers 6.4% vs 15.8%, p < 0.06 16.7% vs 51.2%, p < 0.01 + SPT to grass: 7.7% vs 25.6%, p < 0.02 Not done Not done /
Rennie et al. [154]/Canada 2015 1599 rural adults 1068+ vs 531– 766+ vs 833− Not done Not done Women living on a farm in the 1st yr. of life: atopy (positive SPT) 0.6 (0.4–0.9) Not done Not done /
  1. dd doctor-diagnosed, BHR bronchial hyperresponsiveness, sx symptoms, hdm house dust mite, SPT skin prick tests, JEM job exposure matrix, Lep d Lepidoglyphus destructor