Review article Supported by a grant from Zeneca Pharmaceuticals Health risk assessment of fungi in home environments Arnoud P Verhoeff, PhD* and Harriet A Burge, PhD² Learning Objectives: Reading this article will enable the readers to recognize the public health importance of fungi in the home environment. In view of the recognized impact of fungi on human health, the large population being exposed to fungi, and the large population at risk for developing allergic diseases, there is a need to establish guidelines for allowable exposure to fungi based on a health risk assessment. The aim of this study was to evaluate the status of the data on the relationship between exposure to fungi in the home environment and allergic health effects with respect to the development of such guidelines. Data Sources: The past 10 years of peer-reviewed literature focused on the relationships between respiratory disease and exposure to fungi in indoor environ- ments was examined. Indexing terms included mold, fungi, allergy, asthma, and indoor environment, among others. Each study was evaluated on the following criteria: aim and design of the study, methods for assessing exposure and health effects, and data analysis. Study Selection: Nine population based studies were identified that examined the relationship between allergy and the presence of fungi in the home environment. These studies included quantitative measures of fungal presence in either air or dust. Results: One or more positive associations were found between fungal levels and health outcomes in seven of the nine cross-sectional studies identified. Conclusions: Despite these positive associations it remains impossible to set guidelines for fungi in home environments based on health risk assessment. This is in part because of the cross-sectional study designs, and inconsistency and inade- quate validation of the measures used to evaluate exposure and health effects. Future research designed to generate data that can be used for the development of health risk assessment based guidelines for fungi in home environments should focus on susceptible populations, and use measures that accurately represent exposure and adverse health effects. Ann Allergy Asthma Immunol 1997;78:544–56. INTRODUCTION Since the late 1970s increasing atten- tion has been given to the quality of air in residences, offices, and other public buildings, in part because it is now clear that most people spend a majority of their time indoors and that the levels of some air pollutants are higher in- doors than outdoors. 1 Much attention has been focused on chemical pollut- ants derived from combustion pro- cesses, building materials, and con- sumer products 1–3 and on allergens derived from house dust mites, pets, and vermin. 4–7 The importance of mi- croorganisms, including viruses, bacte- ria, and fungi, is increasingly recog- nized. Several recent epidemiologic studies reported positive associations between home dampness and respiratory mor- bidity of the occupants. 8 –14 These stud- ies also indicated that dampness and fungal (mold) problems are present in 20% to 50% of modern homes. Fungi are regarded as one of the causal fac- tors in the relationship between home dampness and respiratory symptoms, and homes classified as damp tend to have higher levels of fungi than those not so classified. 15–18 In addition, poorly maintained heating, ventilation, and air-conditioning (HVAC) systems have been recognized as sources of microorganisms, including fungi. 1,7 Fungi are well known as sources for allergens that cause allergic rhinitis, allergic asthma, and extrinsic allergic alveolitis (hypersensitivity pneumoni- tis). 19 –23 Probably all fungi that may be abundant in indoor environments pro- duce allergens. 21 Up to 10% of the general population is skin test positive to fungal extracts, 24,25 and among pa- tients with respiratory allergy, 2% to 80% are reported to be sensitized to fungi. 19,26 –28 Niemeijer and De Monchy reported an age dependency of sensiti- zation to aeroallergens, including Cla- dosporium herbarum, in asthmatic pa- tients. 29 The highest prevalence of sen- sitization to this fungus was at age 4 years (42%), declining to 10% or less in patients more than 15 years of age. This finding was confirmed in a more recent study. 30 Patients often show * Department of Epidemiology, Municipal Health Service Amsterdam, Amsterdam, the Netherlands. ² Department of Environmental Health, Har- vard School of Public Health, Boston, Massa- chusetts. This work was conducted in part by Arnoud P. Verhoeff during a Research Fellowship of the Netherlands Organization for Scientific Re- search at the Harvard School of Public Health. Received for publication October 31, 1996. Accepted for publication in revised form April 11, 1997. 544 ANNALS OF ALLERGY, ASTHMA, & IMMUNOLOGY