Who is most at risk for mold allergies? New study uncovers prevalence of mold allergies in the US

8 February 2024

Mold is a natural part of the environment. It thrives in the presence of moisture and oxygen, growing anywhere from the shower in your bathroom to the soil in your backyard.

For some people, exposure to mold causes no immediate health issues. However, others may experience allergic reactions to certain types of mold.

So, who faces the highest risk for mold allergies, and what species of mold are most commonly linked to these allergic reactions? In a study recently published in The Journal of Allergy and Clinical Immunology, researchers set out to answer some of these questions, using Labcorp’s allergy testing data to learn more about mold allergy risk factors.

The study: A comprehensive look at mold allergy prevalence and risk factors

Mold can be found almost anywhere, but researchers are still learning about how common mold allergies are beyond a couple of well-known mold species (e.g., Alternaria alternata, Aspergillus fumigatus).

To learn more about other types of mold allergies, researchers used Labcorp’s extensive database of allergy test results. Between 2014 and 2019, researchers looked at a total of nearly 8 million Labcorp allergy test results for 17 mold types across more than 1.6 million patients. According to the research paper, the study is the most comprehensive of its kind to date to assess the prevalence and distribution of mold allergies in the U.S.

To determine who may be most affected by mold allergies, researchers looked at independent risk factors for sensitivity to specific mold types, including age, sex, certain conditions and disease states, and other environmental considerations.

The results: Who is most affected by mold allergy?

After assessing Labcorp’s test data, researchers discovered a correlation between certain risk factors and the likelihood of experiencing mold allergy.

According to the study’s results, high mold sensitivity appeared to be most common among men, teenagers and those with atopic dermatitis and asthma. Mold sensitivity was also higher in urban areas and in grasslands and prairies, which have drier climates and lower annual rainfall (e.g., Colorado, Oklahoma, Kansas, New Mexico).

In a companion paper to the study, researchers noted that diagnosing species-specific sensitivity to mold can be challenging because many patient samples produce positive results to more than one type of mold (i.e., co-sensitization). In other words, while mold allergies are quite common, researchers are still learning about which mold species cause different types of allergies, and it is often unclear whether co-sensitization happens as a result of similarities between mold types (and, therefore, cross-reactions), or as a result of exposure to multiple mold types in the same environment. Identifying the specific mold type is important, as different types can introduce a variety of harmful immune responses. For example, researchers in the study noted a strong association between mold exposure and asthma symptoms, as well as a relationship between worsened asthma symptoms and house dampness (which can increase the risk of mold growth). A comprehensive allergy test profile design can help differentiate mold types and support allergy management and treatment, especially for those with asthma or atopic dermatitis, as well as people living in urban areas or grassland and prairie regions, where the risk of mold allergy appears to be higher.

To learn more about the prevalence of mold allergies and the most common risk factors behind them, read the full study and its companion paper.