This revision of the 03-31-09 Case Definition reflects our current
understanding of this emerging problem and the results of recently released
information regarding corrosive drywall testing. The sole purpose of this case
definition is to help identify homes that are affected by corrosion associated
with drywall emissions. The case definition is NOT intended to evaluate the
health risks for occupants or to evaluate occupant exposures to corrosive
emissions. This case definition is NOT regulatory in nature or required to be
used by those inspecting homes. This case definition is provided to the public
for informational purposes only and its use is strictly voluntary. Adoption of
this case definition for purposes beyond its intended use is at the risk of the
user. Criteria to demonstrate that a home is not affected by corrosive drywall
emissions may require a different approach and inspection criteria that are not
described in this document.
This version of the case definition enables the user to rank homes as a
possible, probable, or confirmed case. Homes that exhibit the sentinel
indicators of drywall associated corrosion are defined as possible cases. All
three sentinel indicators of Criteria 1 must be met for the
home to be considered as a possible case. Criteria that define a probable or
confirmed case are described in later sections.
For Homeowners
Criteria 1:
Sentinel Indicators of Drywall Associated Corrosion
(Possible Case = all 3)
- The home was constructed or renovated with new drywall since 2001.
- Observed corrosion of air conditioner evaporator
coil exemplified by black corrosion on copper tubing components. The
corrosion can result in refrigerant leakage making it impossible to cool the
home requiring coil replacement. Coil failures indicative of this problem
typically occur every 6-14 months
- Observed metal corrosion, indicated by blackening of
one or more of the following:
- copper wires, ground wires, and electrical connectors
- un-insulated and un-coated copper pipes and fittings
- chrome-plated bathroom fixtures
- silver and copper jewelry
- mirror backing in bathrooms
If you have answered yes to all three of the above indicators, the home meets
the criteria for “possible case”. Continue to Criteria 2 or 3
only if home meets the criteria for “possible case”. Trained
professionals performing home assessments based upon this case definition should
use their experience, training, and professional judgment to establish their
inspection procedures and sampling strategies. Professional judgment is
necessary to determine the number of samples and weight of evidence needed to
meet each set of criteria. A trained professional, not the homeowner, should
conduct inspections and testing described in Criteria 2 and 3.
For Trained Professionals
Criteria 2:
Supporting Indicators of Drywall
Associated Corrosion (Probable Case = 1 or more)
- Observed markings on the back of drywall indicating the
country of origin is China.
- Objective analysis of drywall in home finds Strontium levels exceed 2,000
mg/kg (ppm), indicating the gypsum used in the drywall was probably mined in
China. Analytical methods commonly used for this include XRF and ICP. 2, 3, 5, 7, 8, 9, 10, 11, 12
If you have met the criteria for “possible case” and answered yes to at least
one of the above indicators in Criteria 2, the home meets the criteria for
“probable case”. These criteria do not confirm that the drywall causes
corrosion. Identifying the origin of the drywall is considered a screening tool
for suspect drywall, but confirmation requires analysis described in Criteria
3.
Criteria 3:
Confirmatory Evidence of Drywall
Associated Corrosion (Confirmed Case = 1 or more)
- Elemental sulfur (Orthorhombic sulfur, cyclooctasulfur, S8) content of
gypsum core exceeding 10 mg/kg (ppm), indicating the gypsum in drywall samples
from the home contains the source material that is believed to contribute to the
reduced sulfur gasses emitted from corrosive drywall. Analytical methods
commonly used for this include GC/ECD, GC/MS, or HPLC. 1, 2, 3, 4, 6, 8, 9, 10, 11
- Laboratory analysis of suspect drywall headspace for reduced sulfur gas
emissions (H2S, COS, CS2) indicating drywall samples from the home emit reduced
sulfur gasses capable of causing copper corrosion. Analytical methods commonly
used for this include GC/SCD.6 Results that are indicative
of corrosive drywall must be established by each laboratory based upon internal
procedures, comparison to control samples, and validated methods.
- Qualitative analysis of suspect drywall for its ability to cause
corrosion/blackening of copper under controlled conditions, indicating drywall
samples from the home emit gasses capable of corroding copper. Results that
are indicative of corrosive drywall must be established by each laboratory based
upon internal procedures, comparison to control samples, and validated
methods.
If you have met the criteria for “possible case”, ruled out other sources of
hydrogen sulfide as significant contributors to copper corrosion in the home,
and receive positive results on a sufficient number of samples from one or more
of the above evaluations in Criteria 3, the home meets the criteria for a
“confirmed case”. Some confounding factors that should be excluded as causes of
observed corrosion are hydrogen sulfide from well water, sewer gas, or soil
gas.
Odors and Symptoms
- Use of odors as an indicator of drywall associated corrosion is limited.
Odors have not been reported in all homes exhibiting drywall associated
corrosion.
- Occupant reported health symptoms have limited use in identifying homes with
drywall associated corrosion. The symptoms reported by occupants are not unique
or consistent across affected homes.
- Documenting the presence of odors and/or occupant symptoms may be important
to public health agencies, but their relationship to the presence or absence of
drywall associated corrosion in homes remains unclear.
Remediation
Prior to embarking on efforts to remediate
the home, one should perform sufficient evaluation to ensure the criteria for
“confirmed case” are met and rule out confounding factors.
Please note: The Florida Department of Health has not examined
remediation methods and does not endorse any specific methods or techniques to
conduct an effective remediation of affected homes.
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version
Observed copper corrosion,
indicated by black, sooty coating of Un-insulated copper pipe leading to the air
handling unit present in the garage or mechanical closet of home
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