Saturday, October 22, 2005

Biomass Related Effects - Wet Building Syndrome

BrooklynDodger notes this paper is available to all free in full text. This account should be read with Katrina remediation and biomass remediation generally in mind.

The authors do us a service by putting some actual rates as well as relative rates in the abstract.

There's no mention of environmental measurements or conditions. Typically total mold is higher outside than inside, or in a molded or water intruded building. Also typically, the mold organisms inside the intruded space are different from those outside. There's lots of different mold organisms inside and outside, they are identified to species level. "Species" is a shaky concept for non-sexually reproducing organisms.

[Regarding outdoor vs. indoor mold, readers are reminded that huge numbers of people suffer from the outdoor mold, many taking performance-impairing anti-histamines in large doses in order to function at work and in normal life.]

BrooklynDodger frames the issue of mold or water intrusion this way. There's no [practical]population threshold for respiratory reaction to a biological contaminant, or for infection - the exposure-response relationship goes to very low levels. A single microorganism has a non-zero probability of starting an infection. Subpopulations are hypersensitive or become hypersensitive to sensitizing materials. This sensitivity may be through an allergic type mechanism or some other unknown mechanism. Perhaps there are unknown and therefore unmeasurable vapor phase contaminants.

The large number of agents, large number of [hypothetical] sensitive sub populations, and multiplicative combinations blunt ability to determine exposure response at the individual wet building level. Most of the agents aren't measured because they are not known, and can only be detected by the reactions of the sensitive people.

Likely these unidentified agents, under these conditions, can't be removed to the degree that all sensitives will be symptom free, although the sensitives may tolerate the environment if their livelihood depends on it. [It's circular, they are sensitives because they react, not from any external observable feature.]


The comparison population was the National Health and Nutrition Epidemiologic Survey, NHANES. Prevalence of various answers in this population ranged from current ashma, 13% [2.4 times NHANES predicted], ever asthma 18% [2.2 times], up to "Wheezing, nose, or eye symptoms better on days off work" 72.1% [3.4 times.]

Thus the basic OM question "Is this problem better or worse at any particular time" - strongest answer being "best while on extended time away from workplace, worst the day after returning from extended time away..." is vindicated at the strongest predictor.

On another front, these investigators appear to have used the job content questionnaire. This is very suspect, although more applicable to an office population than an industrial population.

Environ Health Perspect. 2005 Apr;113(4):485-90.

Respiratory morbidity in office workers in a water-damaged building.

Cox-Ganser JM, White SK, Jones R, Hilsbos K, Storey E, Enright PL, Rao CY, Kreiss K.
Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, West Virginia 26505, USA.

We conducted a study on building-related respiratory disease and associated social impact in an office building with water incursions in the northeastern United States. ...Compared with the U.S. adult population, prevalence ratios were 2.2-2.5 for wheezing, lifetime asthma, and current asthma, 3.3 for adult-onset asthma, and 3.4 for symptoms improving away from work (p <> Occupancy of the water-damaged building was associated with onset and exacerbation of respiratory conditions, confirmed by objective medical tests. The morbidity and lost work time burdened both employees and employers.

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