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Hitting a Drywall

In the mid-1990s, while serving as an industrial hygienist and coordinator of the Florida Department of Health's Indoor Air Quality program, David Krause began hearing reports of soot-like deposits appearing on surfaces inside people's homes — in air-conditioning systems, refrigerators and freezers and even the walls. More puzzling, the black stains were often appearing in newly built homes.

Home builders, he recalls, were so befuddled by the recurring soot, or "ghosting," as it's also called, they were actually buying homes back from consumers.

David Krause
David Krause [Photo: Ray Stanyard]

The culprit turned out to be mundane — household candles were producing the specks. Initially skeptical, Krause says, "We were able to demonstrate and actually reproduce it in brand new homes."

Krause has made a career of investigating "oddball contaminants" and unraveling riddles like the candle-soot mystery. For the past year and a half, he's been leading a probe of the possible health effects of Chinese-made drywall.

Complaints about sulfur-like odors and corroded copper wires and pipes in Florida homes began to trickle in to the Department of Health's division of environmental health during the summer of 2008. By December 2008, three months after Krause became state toxicologist, he faced a media firestorm as some homeowners claimed the Chinese drywall also was causing health problems, including coughing and irritation of the eyes, throat and sinuses.

It didn't take long for researchers to figure out how the drywall was corroding copper coils and blackening jewelry. As Krause explains, "Elemental sulfur in gypsum that was mined in China reacts with chemicals that are normally in the environment and releases these corrosive sulfur-containing gases that are uniquely attracted to copper."

It's been a trickier proposition, however, to separate real science from anecdotal evidence and determine what effects the chemicals in the drywall actually have on the body. "In the very beginning, we had very little hard data to evaluate it. What are the chemicals of concern? What are the exposures? What are the concentrations present in the homes?" he asks.

Working closely with the U.S. Environmental Protection Agency and the Centers for Disease Control — and after reaching out to the private sector consultants who'd already begun looking into the problem themselves — Krause and his team devised a strategy to investigate the health effects of the drywall.

Conclusive answers, however, are still elusive. While the testing has uncovered hundreds of chemicals in every home, "so far, the data we have hasn't found any chemicals specifically that are above their known health thresholds or that would pose a specific hazard to the public or the specific people who live in those homes," Krause says.

He says his job is to make sure that the state acts on the basis of real scientific indicators. "My role in all this as state toxicologist is to bring a critical eye to the data and to provide guidance to the state surgeon general and administration as to where this lies in the spectrum of health hazards. Unfortunately, there's a lot of understandable emotion and concerns about this. The scariest thing for most people is the unknown. So it's been one of my biggest challenges to help uncover the unknown — to figure out what facts can we use to make a public health decision."

‘Body burden'

While Chinese drywall has commanded the headlines, it's just one of many items on Krause's agenda. Krause and consulting toxicologist Kendra Goff work on everything from publishing fish consumption advisories that help Floridians avoid unwanted exposure to mercury to dealing with the impacts of landfills and the gases they emit into neighboring communities.

"The data we have hasn’t found any chemicals specifically that are above their known thresholds."
— David Krause

Krause and his staff are also looking for ways to implement bio-monitoring programs to determine the "body burden" of contaminants in people who've been exposed to certain environments — evaluating, for example, the risk posed to someone who's exposed to arsenic-contaminated well water.

Arsenic is a known carcinogen, and in Florida, certain pesticides and farming practices, as well as background levels of arsenic in the soil, have produced elevated arsenic levels in well water in some counties. Although the state administers a testing program to detect arsenic in well water and will install a filter when high levels are detected, there's little way currently to assess an individual's risk associated with drinking that water.

"When the people then ask, ‘Do I need to worry about this? What's the impact?' we currently don't have a good way to evaluate their arsenic uptake and the overall dose and impact it's had on their life," explains Krause. A bio-monitoring system, however, would provide the laboratory equipment to collect and analyze samples of urine or body tissues to ascertain an individual's "dose" of arsenic and the body burden of that particular contaminant. "Then, we can hopefully put their minds at ease or direct people to seek medical attention if they've really consumed more arsenic than they should have."


Copper wiring is taped to drywall — one piece from China — then monitored. Sulfur in gypsum mined in China causes the copper to deteriorate.

Krause and his staff are already developing a bio-monitoring program to test for mercury levels in the bodies of women of child-bearing age. The two pilot projects in Escambia and Duval counties used hair samples to assess their body burden of mercury, an extremely toxic substance that can cause serious health problems including kidney dysfunction, neurological disorders and even death. The women were also educated about the potential danger of eating mercury-laden fish — which Krause concedes is a very nuanced and difficult public health message to deliver considering that fish is also a great source of nutrients.

Krause says people shouldn't avoid all fish, just certain ones —?the higher predators such as sharks, some of the larger tuna and certain freshwater varieties like bass. "And certainly, never eat a python. We were asked that question, since they opened a python season in the Everglades, the natural question became, ‘Well, can we eat them?' From the little bit of data we've been able to find — no."

David Krause, 42
State toxicologist, Bureau of Environmental Public Health Medicine

Hometown: Tallahassee native

Hobbies: Hunting and fishing

Education: Ph.D., environmental and occupational health, University of South Florida (2005); master of science in public health, toxicology, USF (1999); B.S. biological sciences, Florida State University (1989)

Military Experience: In 1989, Krause was commissioned a lieutenant through the U.S. Army ROTC at FSU and went to Germany for four years. "I was there when the (Berlin) Wall fell. Part of my job there, I was actually in artillery, but part of my job was to close down some military bases, hand them back over to the Germans before we left, and that's where I got my first experience in dealing with environmental contaminants and how they're cleaned up and detected and monitored."

Private Sector: From 1997 to 2008, Krause ran his own consulting firm, Indoor Air Solutions.

Indoor Air Pollution: "A lot of people don't realize that people spend most of their time indoors. Between home and work 90% to 95% of time is spent indoors, and that's where you're most likely to have adverse environmental exposures if you have any."

Tip: Krause says all homeowners should open their windows at least once a day, usually in the morning or the afternoon, before or after the major heat of the day. "Between cooking and showers and all of the furnishing and materials we use — there's a lot of chemicals that are released, most of which are harmless, but some can cause irritation."