Despite a wealth of anecdotal evi-dence indicating that healthy peo-ple can become chronically illfollowing exposure to indoor molds,a federal science panel could notdraw a conclusive cause and effectlink between the two. This findingwill make ongoing state and feder-al legislative efforts to craft safe ex-posure thresholds in response togrowing public concern and litiga-tion over mold more difficult, poli-cy analysts say.

In a report released at the endof May, the Institute of Medicine(IOM), an arm of the U.S. NationalAcademy of Sciences, concludedthat damp conditions in homesand buildings could exacerbate res-piratory problems, such as asthma,in sensitive individuals. Likewise,these conditions, which are linkedto “sick building syndrome”, are as-sociated with coughing and wheez-ing in otherwise healthy people. Adearth of scientific data, however,made it impossible for the panelto establish a clear causal relation-ship between mold exposure andthese illnesses, as well as a widerange of other health complaintsthat have been attributed to sickbuildings, such as brain or neuro-logical damage, reproductive prob-lems, and cancer.

“There’s a lot of informationmissing, and that’s why we said weweren’t able to find these associa-tions, but we weren’t able to rulethem out either,” notes HarrietAmmann, a senior toxicologist forWashington state’s Department ofEcology and a member of the IOMpanel. Part of the problem may bebecause scientists were measuringthe wrong components of the molds(see related story on next page).

Other big shortcomings stemfrom the lack of good methods formeasuring exposure to bioaerosols,as well as the exposure levels nec-

essary to cause an adverse healthimpact. Without such exposure–response data, “This issue will defysetting safe exposure thresholds,”notes Bert Brunekreef, an envi-ronmental epidemiologist at theUniversity of Utrecht in The Nether-lands and a panel member.

Moreover, other biological orchemical agents could be producingthe health effects currently being at-tributed to mold. The report pointsout that damp indoor environmentsalso favor the spread of dust mitesand cockroaches, for example, whichcan produce significant allergensand have been implicated in asthmasymptoms. Excessive dampness canalso damage building materials andfurnishings, initiating the release ofchemical emissions and nonbiolog-ic particles.

Panel members are hopeful, how-ever, that the tools of toxicogenomicswill improve scientists’ ability to makethe relevant measures of concentra-tions and exposures that cause ad-verse health effects.

Meanwhile, Congress and es-pecially state legislators will behard-pressed to make decisionson regulations, predicts AaronTrippler, government affairs direc-tor for the American IndustrialHygiene Assoc., noting that a Con-gressional bill (H.R. 5040) intro-duced in 2002 to address growingmold concerns has gone nowhere.Neither has legislation enacted inCalifornia two years ago puttingtogether a task force to advise thestate on establishing permissiblemold exposure limits (Environ. Sci.Technol. 2002, 36 (1), 11A).

Other complications includethe existence of thousands of dif-ferent mold species. “You’d haveto set a threshold for each one,”explains Glenn Fellman, executive di-rector of the Indoor Air QualityAssociation. Additionally, people’s re-

Indoor mold standard could prove elusive

AUGUST 1, 2004 / ENVIRONMENTAL SCIENCE & TECHNOLOGY ■ 281A

Adapting to climate changeBecause the world has already passedthe point where climate change canbe prevented entirely, the U.S. govern-ment and economic sectors must takesteps now to adapt to the impacts of aprojected increase in global tempera-tures of 2.5–10.4 °F by 2100, accordingto a report from the Pew Center onGlobal Climate Change. Coping withGlobal Climate Change: The Role ofAdaptation in the United States con-cludes that proactive adaptation canreduce the severity and cost of ad-verse impacts if warming occurs atthe lower end of the projected rangeof magnitude. Strategies include re-moving subsidies that pay farmers toplant specific crops in specific areasand promoting free-market water pur-chases. To download the report, goto www.pewclimate.org/docUploads/Adaptation%2Epdf.

Just locks and fences?Although an accidental release or ter-rorist attack at any of more than 100chemical facilities across the UnitedStates could injure or kill at least 1 mil-lion surrounding residents, the indus-try continues to use and store largeamounts of toxic chemicals, accordingto a report from the U.S. Public Inter-est Research Group, a national advo-cacy group. The Dangerous Dozen:A Look at How Chemical CompaniesJeopardize Millions of Americansis based on required risk-manage-ment plans submitted to the U.S.EPA from 12 large companies thathave thousands of facilities acrossthe country. The chemical industryand the Bush Administration em-phasize physical security programs,according to the report. The reportis available at http://uspirg.org/uspirg.asp?id2=13532&id3=USPIRG&.

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For the first time, researchers havemeasured airborne mycotoxins inmoldy buildings, providing a possi-ble link between “sick building syn-drome” and human health.

“We believe that we are pioneers,the first to find these toxins in na-tive, mold-contaminated buildings,”says Trevor Brasel, a graduate stu-dent in the lab of David Straus, pro-fessor of microbiology andimmunology at Texas TechUniversity’s Health SciencesCenter. “I think it opens upthe door to new research.”The study was presented thisMay at the American Societyof Microbiology meeting inNew Orleans.

“Previous studies lookedat agents that carried toxins[such as spores], but not thetoxins themselves. So, thismight be a good step in theright direction,” says HarrietAmman, a senior toxicologistwith the Washington state de-partment of ecology. Accordingto Amman, very little scientific evi-dence exists to link mold with healthproblems often lumped together assick building syndrome. Symptomsof sick building syndrome includeheadache, dizziness, and fatigue.Nevertheless, hundreds of lawsuitshave been filed and billions of dol-lars have been paid by insurancecompanies to fix buildings withmold problems.

Last May, an Institute of Medi-cine panel found evidence thatmold and indoor dampness corre-late with asthma and other respira-tory problems but was unable toshow a correlation with sick build-ing syndrome (see story on elusive

mold standards on previous page).In the new study, Brasel placed a

bioaerosol sampler in mold-contam-inated buildings to measure pollu-tants. The sampler was originallydesigned to detect biowarfare agents,and similar models are now locatedin U.S. post offices to protect work-ers against contamination duringmail sorting.

The collected samples were testedagainst antibodies (using an ELISA)for macrocyclic trichothecenes, whichare the most toxic substances pro-duced by the common indoor moldStachybotrys chartarum. At low lev-els, trichothecenes can cause skin ir-ritations, but the toxin can be lethalif ingested in the range of milligramsper kilograms of body weight.

In the six environments with S.chartarum, the toxin levels variedfrom 12 to more than 1200 pico-grams per cubic meter of sampledair. The effects of such airborne lev-els are not known because inhala-tion studies with the toxin have notbeen conducted. Toxin levels were

significantly lower in environmentsthat lacked mold growth.

Even in buildings that did nothave mold problems, the analysisdetected the toxins, but at signifi-cantly lower levels. “We got morebackground noise than we wouldhave liked, but when you go into aStachybotrys environment, you candefinitely see a significant differ-ence,” adds Brasel.

He attributes the backgroundto false positives and nonspecific

binding. “The air sampler iscollecting at a rate of 450 litersper minute,” says Brasel. “Soyou’re collecting all types ofcompounds, and you can imag-ine that some of them mighthave cross-reactivity to theantibody.”

Mold toxins may be onlypart of the sick building syn-drome, say experts. Besidesfavoring mold growth, mois-ture increases levels of bacte-ria and dust mites, as well asthe release of chemicals suchas formaldehyde from ply-wood. “The problem is thatthere are so many things in

the air that interfere with any typeof analysis,” says Bruce Jarvis, pro-fessor of chemistry at the Universityof Maryland. “You would like tohave some idea of exposure to my-cotoxins, which this work address-es. The second and more valuablething would be to have biomarkersin people that would be a measureof their exposure to these toxins.”

Brasel says others in his lab arenow looking for this additional evi-dence. One group is testing housesfor airborne mycotoxins and thensurveying the residents for health dis-orders. Another project is examininghuman serum to locate biomarkersof exposure. —PAUL D. THACKER

282A ■ ENVIRONMENTAL SCIENCE & TECHNOLOGY / AUGUST 1, 2004

Environmental▼Newsactions to mold range from one ex-treme to the other, and levels of moldare constantly fluctuating. “You can’tturn them off and on like you canwith a chemical substance,” Fellmannotes, so “maintaining a consistentexposure rate of so many parts-per-million of some species of moldspore in the air would be hard to do.”

Instead of establishing safe expo-sure thresholds, panel members saythe focus might be better placed onpreventing or quickly remediatingthe moisture problems that lead tomicrobial growth in the first place.Key to this effort is public educationon proper building maintenance, aswell as national guidelines for the

construction industry, where energy-efficient designs have been linked toa higher rate of indoor mold infesta-tions (Environ. Sci. Technol. 2002, 36(5), 95A–96A).

For more information, the IOMreport, Damp Indoor Spaces andHealth, can be accessed at www.nap.edu. —KRIS CHRISTEN

Airborne mycotoxins discovered in moldy buildings

American insurance companies have spent billions ofdollars dealing with the thousands of cases filed everyyear in mold-related lawsuits. The majority of thesecases occur in states with high humidity such as Texasand Florida.

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