Review Calls for Mycotoxins Research

Industrial hygienists are asking for more research about the presence of molds and mycotoxins in indoor environments.

Epidemiological studies of exposure and effects are necessary for healthcare workers because of the importance of health risk detection. A new method of estimating exposure to molds is also necessary.

Molds are fungal organisms. Fungi cells have a nuclear envelope and are eukaryotes, making them different from bacteria and algae. Fungi include molds, rusts, smuts, and mushrooms.

Mycotoxins, or substances produced by mold growing in food or animal feed, cause illness and death when ingested by humans and animals. There are no exposure standards for molds or mycotoxins. Industrial hygienists need research to further understand the exposure potential and health effects associated with the inhalation of mold in indoor environments. There have been many studies on animals that have ingested mycotoxins, but few studies on the impact of inhalation.

However, people become ill from inhaling mycotoxins and molds frequently.

The "indoor environment" toxicologists want more research on offices, commercial buildings, and residences.

The health effects of molds in indoor air include three specific categories. Allergic reactions cause rhinitis, asthma, or hypersensitivity pneumonitis. Growth of fungus in or on the body as with aspergillosis or histoplasmosis are signs of an infectious reaction. Toxic reactions cause a disruption of cellular function and interaction with the DNA. This can lead to aflatoxin-induced cancer.

Mycotoxins affect humans by interfering with cellular respiration, carbohydrate and lipid metabolism, and direct binding with DNA and RNA. These are generally large, complex molecules and are not volatile.

Mycotoxins consist of many diverse mold compounds. Those that effect humans the most include Aspergillus, Fusarium sporotrichioides, Penicillium, and Alternaria.

Aspergillus infects humans orally. Foods that can be contaminated include peanuts, pecans, peas, bread, cheese, rice, corn, barley, grain, sorghum, wheat, and cotton seed. Animals studies showed that inhaled aflatoxins are immunosuppressive and may be carcinogenic. This caused the 1960s outbreak of "Turkey X disease" when hundreds of thousands of turkeys died after eating aflatoxin-containing peanut meal.

Human ingestion of aflatoxin has been linked to liver cirrhosis and Reye's syndrome. Inhalation cases have show aflatoxin exposure may cause lung disease and cancer.

Fusarium sporotrichidides is a mold species that researchers think killed thousands of people in the USSR after WWII. People were starving and ate grain left under winter snow. People experienced bone marrow damage, leukopenia, pancytoneia, gastroenteritis and death due to hemorrhage. The outbreaks were originally thought to be diphtheria or cholera, which have similar symptoms.

Penicillium is another mold that produces dealthy mycotoxins. It is responsible for Balkan nephropathy. This chronic, fatal kidney disease of humans only occurs in the Balkan Valley. Researchers think the disease comes from tainted foods.

Alternaria is a ubiquitous mold. It is not thought to have a serious role in human disease but is an allergen.

With limited knowledge of inhalation effects of mycotoxins, researchers have look at ingestion case studies for information. Most people used in these studies were farm workers who either slept on infected straw mattresses or dealt with infected feed. As a whole, the case reports show that significant health effects occur after human exposure to high levels of bioaerosols.

However, there are no standard methods of quantitative sampling of mold-contaminated surfaces. Strategies need to be developed to analyze indoor and outdoor molds nationally. A database of these molds would help researchers pinpoint dangerous mycotoxins.

Although most people know that mold is unsanitary in indoor conditions, the direct health threat of breathing these spores is unknown.

More information about the molds and new sampling techniques could help determine acceptable levels of mold exposure in indoor environments.

Information from Applied Occupational and Environmental Hygiene