Exposure to endotoxin decreases the risk of atopic eczema in infancy: a cohort study

J Allergy Clin Immunol. 2001 Nov;108(5):847-54. doi: 10.1067/mai.2001.119026.


Background: Previous studies have shown a protective effect of early exposure to cats and dogs on the development of atopic eczema, asthma, allergic rhinitis, and atopic sensitization in later life. In particular, a higher microbial exposure to endotoxin in early childhood might contribute to this effect.

Objective: We examined the associations between bacterial endotoxin in house dust and atopic eczema, infections, and wheezing during the first year of life in an ongoing birth cohort study (LISA).

Methods: Data of 1884 term and normal-weight neonates with complete information on exposure to biocontaminants and confounding variables were analyzed. House dust from the mothers' and the children's mattresses was sampled 3 months after birth. Endotoxin content was quantified by using a chromogenic kinetic limulus amoebocyte lysate test.

Results: During the first 6 months of life, the risk of atopic eczema was significantly decreased by endotoxin exposure in dust from mothers' mattresses in the fifth quintile (odds ratio [OR], 0.50; 95% CI, 0.28-0.88), whereas the risk was increased for respiratory infections (OR, 1.69; 95% CI, 1.25-2.28) and cough with respiratory infection, bronchitis, or both (OR, 1.73; 95% CI, 1.28-2.33). The risk of wheezing was also significantly increased during the first 6 months of life (OR, 2.37; 95% CI, 1.40-4.03). For the entire first year of life, these associations attenuated, except for the risk of wheezing, which remained significant (OR, 1.60; 95% CI, 1.10-2.30).

Conclusion: Our findings support the hygiene hypothesis that exposure to high concentrations of endotoxin very early in life might protect against the development of atopic eczema within the first 6 months of life, along with an increased prevalence of nonspecific respiratory diseases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Air Pollution, Indoor / analysis
  • Allergens / analysis
  • Beds
  • Cohort Studies
  • Dermatitis, Atopic / diagnosis
  • Dermatitis, Atopic / etiology*
  • Dust / analysis
  • Endotoxins / analysis*
  • Environmental Exposure
  • Humans
  • Infant, Newborn
  • Respiratory Sounds / diagnosis
  • Respiratory Tract Infections / diagnosis
  • Respiratory Tract Infections / etiology
  • Risk Factors


  • Allergens
  • Dust
  • Endotoxins