Health effects of mold not fully known

By Jim Shamp : The Herald-Sun   Aug 16, 2003

DURHAM -- N.C. Central University officials are being prudent as they broaden mold cleanup efforts to more than a dozen campus buildings, even though they lack the support of solid scientific evidence of the mold's potential hazards, specialists say.

But a leading national group of scientists is expected to unroll the best available evidence sometime during the next four months, possibly offering guidance for future research and cleanup efforts.

"The bottom line is that we still do not know how much exposure it takes to which molds to produce significant health effects," said Dorr Dearborn, professor and director of the MaryAnn Swetland Center for Environmental Health at Case Western Reserve University in Cleveland.

"It's not a simple thing like lead exposure, in which we can measure blood levels and know 'this much' will cause 'these sorts of problems.' Instead, we're dealing with multiple molds that may or may not be producing multiple toxins and may or may not be producing multiple health effects," said the pediatric pulmonologist, a lung specialist, who conducts mold research and also treats children at Cleveland's Rainbow Babies and Children's Hospital. Rainbow is the primary pediatric teaching hospital for the Case Western Reserve School of Medicine.

Scientists have known for a long time that molds can trigger allergies in sensitive people, said Dearborn. And even though he hasn't been consulted on the NCCU mold problems, he said he understood why university officials would choose to close buildings pending cleanup.

"Institutions need to exercise prudence so people don't get sick," he said. "But they also don't necessarily need to evacuate every building containing mold. We just don't have concrete data to tell people how to walk that line."

Some of the uncertainty over mold toxicity is to be addressed within the next two to four months in a report from the Institute of Medicine, an arm of the National Academies of Science, said Dearborn.

"They've been debating this for almost a year and a half, and they're coming up with a report on the current state of the art, and the state of research on indoor air quality including mold toxicity." The study, for which he provided some consulting, was commissioned by the Centers for Disease Control and Prevention's National Center for Environmental Health, he said.

There's a lot of published research information about the dangers in eating some toxic molds, he said. "But the current level of knowledge is inadequate regarding the usual inhalation of molds in living environments."

Whenever society doesn't have enough knowledge to establish safety standards in those kinds of situations, there's controversy, he added. "It can range from hysteria, being blown out of proportion by rather large lawsuits, for example, to the other extreme, of inadequate public health prudence."

"I wouldn't want to dismiss any of this," said Darryl Zeldin, a pulmonologist and senior investigator with the National Institute of Environmental Health Services in Research Triangle Park.  "You always want to be conservative about this sort of thing.  But just because there's fungus in a building doesn't mean it will cause serious disease among people inhabiting that building.  Before throwing millions of dollars at it, I'd want to get opinions from the top experts."

Dearborn said the ideal way to approach a mold problem is to hire an environmental consultant certified by the American Industrial Hygienist Association.  These consultants are skilled at deciding where sampling is needed, finding sources of water intrusion, and acting as a supervisory contractor for separate cleanup or construction firm.

"It works best if those two entities are separate corporations," he said, "like an architectural firm looking at a general contractor to make sure he does it right."

Dearborn said modern building techniques have created "new ecologies" with new problems, in part because builders now use paper-covered gypsum board, called wallboard, rather than lath and plaster for wall surfaces.

"The gypsum part of the wallboard can hold water for a long time," he said, "so you then have moisture held into the paper covering it. Mold is normally not a problem because it's slow growing and requires continuous moisture to support it. But if you have a chronic moisture situation on a substrate such as this paper, you can have mold. And molds capable of producing toxins, such as the Stachybotrys chartarum [the black mold reportedly concerning NCCU officials], love to grow on wallboard."

In fact, said Dearborn, he and colleagues use wallboard samples in their lab as a growth medium for Stachybotrys in experimental studies.

Another modern building technique contributing to mold problems, especially in the United States, is improper air handling associated with heating and air conditioning, said Dearborn. It's been increasing during the past 30 years, fueled by energy consciousness.

In general, many buildings are sealed to prevent inefficient air leaks. But contractors don't then provide for the necessary exchanges of stale, moist indoor air with fresh air from outside. "If you were to build a new home in Ontario, for example, you'd have to build the ventilation system so it would turn over ? air several times in 24 hours," said Dearborn.

Ventilation contractors also tend to use oversized air conditioning units, chilling indoor air too quickly without letting it become dehumidified, thus according to Romie Herring, industrial hygiene consultant supervisor with the Occupational and Environmental Epidemiology Branch of the state Department of Health and Human Services' Division of Public Health.

"When dehumidification isn't properly considered in the design, it can really be a problem in buildings where you have widely varying heat loads, such as in dorms or classrooms," said Herring. "They have a lot of load when students are in there, but that changes when students leave the building. Sometimes people cycle the systems, too, turning them off at night thinking they'll save energy. I don't know what they're doing at NCCU, but some places do that. And that can add to moisture problems."

Herring said his agency hadn't been contacted by NCCU officials, even though they're sister state agencies. "I don't know if the NCCU health and safety officer even knew we were over here," he said. "But we do provide assistance to state agencies, typically as they request it, on dealing with indoor air quality issues." He said his agency had worked with other state universities in dealing with mold problems.

"Our position, from the practical standpoint, is that if you have mold, you have a moisture issue," said Herring. "And that has to be addressed. Mold typically is eating dead materials. It's attacking the building. So without even getting into what causes what from the health standpoint, we don't need buildings to be attacked."