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In 2008, homeowners in several southern U.S. states began informing federal authorities that something in their homes was awry.  The complaints were very similar and boiled down to three problems: (1) unpleasant emissions and odors in their homes, (2)  unexplained corrosion of pipes, mirrors, outlets, AC units and wiring, and (3) health problems, notably nosebleeds and respiratory disorders. 

There was immediate speculation by some homeowners that the culprit was imported drywall recently installed in their homes.  The drywall in affected homes was imported to the U.S. during a building materials shortage following the boom in rebuilding in several Gulf Coast states following several weather events, notably Hurricane Katrina.  A conservative estimate that 50,000 homes have been affected with the toxic drywall elevated the issue to a national one and a multi-federal agency launched an investigation.  

In late October 2009, the investigation, led by the U.S. Consumer Product Safety Commission (CPSC), found that the imported drywall contained higher than normal levels of sulphur, among other chemicals, but failed to come up with a culprit in the imported drywall for the health and corrosion problems.  Homes affected include not only those located in Gulf Coast states, but in all corners of the continental U.S., from Washington State to Maine to California to Florida.

One problem that was likely overlooked by the investigation was that the drywall in the affected homes was made with a type of gypsum called phosphogypsum.   Drywall is usually made with naturally-occurring gypsum-rock (a white, chalky substance) and water, but gypsum could be substituted by phosphogypsum, a waste byproduct from the production of phosphoric acid (phosphoric acid is a 'building block' of phosphate fertilizers and also livestock feed ¹⁾.  

Phosphogypsum waste has relatively high levels of radioactivity and the phosphate industry, which is primarily located in the U.S. in Florida, has tried to dispose of it instead of facing a waste storage problem: piling it up into unsightly and potentially-dangerous 'stacks.'   

The Florida phosphate industry's ability to rid itself of phosphogypsum had been hampered mostly by public opposition, fueled by fears over radon gas exposure, and, ultimately, by a law passed in the U.S. in 1989 that banned use of phosphogypsum in construction.   The EPA did, however, pass a 1992 rule that allows reuse of phosphogypsum if the radioactivity is about 1/3 of that generated in waste (less than 10 pCi/g of Ra226).  

The EPA allows this 'phosphogypsum-lite' to be used in research and agricultural applications.  Yep, northern Florida farmers use it as a 'soil conditioner' - to 'fertilize' their fields, and peanut farmers in Georgia use 'PG-Lite' on their fields because it helps 'strengthen' the peanut shells.  Farmers in several North Carolina counties whose fields had been sprayed with salt water from hurricanes use it on their fields - 'PG lite' is good on farms with high quantities of salt or low concentrations of calcium or other nutrients.  (Actually, much of the food we eat is 'supplemented' with uranium and 'decay products' because it is grown in soil 'fortified' with fertilizer, a phosphate industry product made from phosphate deposits, which are slightly more radioactive than normal soil.  What phosphogypsum is is the waste product from fertilizer manufacturing.  What's more, part of the cancer-causing properties of cigarettes comes from radioactive lead, polonium and radium, which concentrates in the tar and is 'added' by the heavy use of phosphate fertilizer in tobacco fields. EPA: "For example, phosphate fertilizers, favored by the tobacco industry, contain radium and its decay products (including lead-210 and polonium-210). When phosphate fertilizer is spread on tobacco fields year after year, the concentration of lead-210 and polonium-210 in the soil rises.")

The Florida phosphate industry is itching at preventing the growth of their 'stacks' - total weight: 1 billion tons, growing at the rate of 30 million tons per year - and would prefer spreading it out into society using the rationale that the risk from disasters that regularly plague huge and growing 'stacks' is greater than the radiological exposure if the EPA allows it to be put in roads (btw, there are already roads with it paved in central Florida) and on farms, and possibly other mainstream applications.  

There is an obvious solution that the phosphate industry is overlooking: stop making phosphogypsum waste.  

Astonishingly, the U.S. government has never instituted an import ban on phosphogypsum drywall.  For many decades after World War II, the U.S. has benefited from an ample supply of home-grown gypsum wallboard, but the hurricane impacts in the 2000s dwindled U.S. supplies and forced distributors to import drywall from as early as 2001 to 2008 (and mostly in 2006) from China, which has no regulations against putting phosphogypsum into building materials. 

The danger of phosphogypsum in building materials stems from the substance's relatively high density of naturally-found radioactive chemicals including radioactive radon gases and radium-226.  Radium-226 is a radioactive solid substance that occurs in nature but if inhaled in significant quantities can increase lung cancer risk.   It emits gamma rays that can penetrate through walls and paint.  

On October 29, 2009, the federal agencies looking into the imported drywall problem stated in a press release regarding radioactive materials that ‘Testing conducted over the summer by federal and state agency radiation laboratories found no radiation safety risk to families in homes built with manufactured drywall. The strontium found in this drywall does not pose a radiological risk.’  

It is important to note, however, that the U.S. EPA, which conducted radiological analyses, looked at only 21 samples of unpainted drywall for radioactivity (in the summer of 2009) and only 7 samples were from overseas manufacturers and there was no indication if any of these came from China!  The EPA claimed the entire group of samples had about the same amount of radiation as each other and no more than is typical “background” radiation in the environment, but disclaimed in a technical report that 'because of the small number of samples, the Technical Team cannot conclude that these samples represent all imported and domestic drywall nor that the results demonstrate statistical significance.'  

It is unclear if the EPA considered what will happen when contractors and DIY homeowners working on improvement projects are demolishing walls and breathing in radioactive dust.   Consider that Chinese drywall is more fragile, and falls apart more easily than U.S.-made drywall.  Consider that phosphogypsum has relatively high levels of Polonium-210, the toxin that poisoned Alexander Litvinenko, as well as radioactive isotopes of lead, thorium and bismuth, all 'daughter products' from the decay of Uranium-238, which is the main ingredient in Depleted Uranium.  

In the late 1970s, the NRC began showing concern over phosphogypsum in building materials and related health impacts and in their 1978 document noted a study published 2 years earlier that "[suggested] that it is not unlikely that the total dose (external gamma and internal alpha) to the bronchi of occupants of homes built with uranium-bearing materials over a 50-year period at an average of 15 hr/day would approach that at which the incidence of lung cancer in uranium miners is doubled."   Health physicists today note that even when drywalls are intact there is a radiological hazard from the gamma rays from radium-226 and the inhalation of alpha-emitting radon-222 gas and that this could add one-third to a persons' yearly total radiation exposure.    

It is difficult to know without adequate scientific studies if the Chinese drywall in Americans' homes is radioactive.  Phosphogypsum's naturally-radioactive content depends on the levels in the phosphate deposits that were mined, however China's phosphate deposits are just as 'bad' as Florida's.   (Affected homeowners also have complained that the drywall is causing corrosion of coils and metals nearby walls but it is unclear if radionuclides in phosphogypsum can be blamed.)  Sadly, the only comprehensive analysis so far on this entire issue was done by the Los Angeles Times in its July 2009 investigation and nothing substantive has been put forward by government or the media since then.  

What should I do?  Contact the CPSC (http://www.cpsc.gov/about/contact.html) and tell them what you now know.  Maybe they’ll start testing and banning consumer materials that emit high levels of radioactivity, like some ‘steel’.  Oh, you didn’t hear about radioactive steel?  Read more on our Nuclear World page.

Initial EPA analysis: http://tinyurl.com/ylmg2jj

CALCULATION SECTION:  One of the samples that was of the imported drywall group (sample #53) stood out from the others and contained a higher-than-average 2.06 picoCuries per gram of Radium-226 (226Ra; EPA NAREL).  (The EPA report doesn't clarify if the imported drywall samples were indeed from China, or elsewhere.)   The EPA's 'inhalation slope factor' for Radium-226 is 0.000000116 risk per pCi.  What this means is that each picoCurie of Radium-226 inhaled will incur an age-average, lifetime attributable radiation cancer risk in 0.000000116 persons.  If one considers that, hypothetically, on average, every home under-construction or under-remodeling creates 200 pounds or about 100,000 grams of drywall dust and 1/100 of it is  inhaled by each resident (or contractor), then 1,000 grams of drywall per person will be internalized with (hypothetically) a dose of 2,000 picocuries of radium.  Per the factor of 0.000000116 risk per pCi, the afflicted would have an increased risk of cancer of 0.023 percent.   If 25,000 homes are afflicted - each with a household size of 4 (total 100,000 people) - then about 23 persons will have an age-adjusted additional cancer risk from the inhaled and ingested radium.  Because of the EPA's small sample size, it may have missed sizeable quantities of Chinese drywall with extremely high amounts of radioactive radium in it.  There's speculation that a very large percentage of all imported Chinese drywall has phosphogypsum in it.  Since the radioactivity (Ra226 concentration) of phosphogypsum (in the U.S.) can range as high as 35 pCi/g and, also, since some imported China drywall is made of 100% phosphogypsum, then the risk of cancer in a worst-case hypothetical scenario would be 0.40 percent.  If 100,000 people are affected, then about 406 persons will have an age-adjusted additional cancer risk; the non-cancerous maladies could be in the thousands.  

In 2006, China exported over 500,000,000 pounds of drywall; in 1993, the United Nations Scientific Committee on the Effects of Atomic Radiation quoted a typical value of 24 pCi/g of 226Ra in phosphogypsum

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For a purely mathematical exercise to begin to grasp the risk to a large population of internal radium-226 exposure, let's assume - very broadly - that each person in lower Manhattan in September 2001 breathed in, during that month, a similar amount of dust as they would in a home construction project over several weeks (inhaling 1,000 grams of wallboard dust).  (Each tower had upwards of 8 billion grams of drywall and dust samples 'downwind' showed that up to 30-40% of the dust composition was drywall powder).  Since we don't know the 'quality' of all of the gypsum drywall in both WTC towers (in terms of Radium-226 content), we will outline below the risk from low and high radium-226-content gypsum (2 pCi/g and 35 pCi/g).    Assuming a population of 1,400,000 persons exposed to the WTC dust during September 2001, there would be 322 to 5,684 extra cancer occurrences just from the radium-226 in lofted drywall dust.  

2 pCi/g Ra226 sheetrock	35 pCi/g Ra226 sheetrock
0.023% cancer risk	0.406% cancer risk
1,400,000	1,400,000
322 extra cancers	5,684 extra cancers

The drywall dust in lower Manhattan (dispersed in the outdoors and tracked inside buildings where it's hard to remove) had other harmful 'uranium daughters,' including Polonium-210 and Lead-210*.    Assuming these radionuclides are found in the same proportions in gypsum rock deposits as Radium-226, and thus the drywall dust, we can add to the inhalation slope factor of Radium-226 of 0.000000116 the slope factors for inhaled Po210 (0.000000108) and Pb210 (0.0000000277) to equal 0.000000252.  This combined risk factor is about two times the risk factor for Radium-226, so the above cancer risk estimates can be doubled to reflect the three most dangerous (for inhalation) radionuclides in gypsum.  The cancer risk totals could be even larger if the quantities of inhaled dust were greater than above estimates.

Smoke detectors and WTC radioactive dust The dust downwind of the WTC 'ground-zero' (a.k.a. 'The Pile') also contained radioactive Americium-241, a human-made radiological substance used in most commercial smoke detectors (although there are perfectly functioning, and much safer, smoke detectors that don't use radiological substances).  These smoke detectors commonly have in them about 9 millionths of a Curie of Americium-241.  This is also written as 9 microCuries.  If we assume that a smoke detector is installed every 100 square feet in a commercial building, and each WTC tower measured 3.8 million square feet, then 38,000 smoke detectors were in each tower (WTC1 and WTC2), and 76,000 combined in the twin towers.  The amount of Americium-241 in these 76,000 smoke detectors equaled 0.684 Curies, also written as 684,000,000,000 picoCuries.  (A picoCurie is a trillionth of a Curie.)   However, not all of this Americium was inhaled; most fell to the ground and was washed or hauled away.  Perhaps 1/10,000 of it was inhaled in September 2001 by residents and workers in lower Manhattan, a population of 1.4 million people.  Using the EPA inhalation slope factor for Am-241 of 0.00000000281 per picoCurie per year, the risk of this dose level to a population is 0.19 extra cancers per year.  In a population of 1.4 million that equals 266,000 extra cancers from inhalation of Americium-241 dust from the twin towers collapse.  Curies per detector = 9 microCuries Am241  or 9,000,000 pCi smoke detectors in both towers=76,000 total Curies  =684,000,000,000 pCi 1/10,000 inhaled = 68,400,000 pCi EPA risk factor for Am241  0.00000000281/pCi risk factor = 0.19 risk factor X population = 0.19 * 1,400,000= 266,000 extra cancers Read about the gamma-emitting dangers of smoke detectors from the Low-Level Radiation Campaign, and why going to the toilet in an airplane may not be safe for your health - here According to 'Let the Fact's Speak: An Indictment of the Nuclear Industry' (2006), in France on 10/9/1999, "a truck loaded with 900 smoke detectors, containing americium-241, and highly flammable materials caught fire on a highway in eastern France. Total radioactivity of the smoke detectors was some 4 megabequerel (MBq). About 40 people (police, firemen, and highway service personnel) were identified as potentially contaminated. The truck was not marked with the standard radioactivity sign." [4 MBq= 4,000,000 Bq, or 108 million pCi]

*The USGS publication titled "USGS Environmental Studies of the World Trade Center Area, New York City, after September 11, 2001," (USGS Factsheet FS-050-02, October 2002), illustrated that the dust deposits, according to a graph on page 4, had levels of uranium that were above the mean concentrations found in natural soils in the eastern United States; uranium indicates the presence of naturally occurring radionuclides from building materials.

END OF CALCULATION SECTION

¹  Some facts: 

• For every 1 ton of phosphate rock processed to make fertilizer by the wet process, about 5 tons of phosphogypsum is created.  

• 'Drywall' is another term for - and means the same thing as - wallboard, gypsum board, sheetrock, etc...

• In 1989, 10% of phosphogypsum was disposed of in the sea, the rest in landfills. 

• In 1990 the EPA mandated that the substance be disposed of in stacks on plant sites or as backfill in phosphate mines.

• Phosphogypsum is about 75% sulfur

• Mounds and mounds - totaling over one billion tons - of phosphogypsum line Florida's horizons in about 25 mountains officially called 'stacks,' but also dubbed 'gyp-stacks.'  These are 'Florida's mountains.'  The highest elevation in Florida is just over 300 feet, on the top of a gyp-stack!   Florida produces 75-80% of the phosphate in the U.S. and these mounds are an eyesore, and environmental threat (leaching radionuclides; shooting out gamma rays; off-gassing radon); see picture of a HUGE stack; 'mounains' in Lithuania; more stacks; more stacks. These stacks are not immune to sinkholes particularly because those are common in Florida; in 1994, a 15-story sinkhole formed below an 80-million ton gyp-stack maintained by IMC Agrico and apparently contaminated the aquifer that supplies 90% of Florida's drinking water with 4 to 6 million cubic feet of industrial waste-water!  The stack was at Agrico's New Wales plant in Mulberry, FL: the sinkhole opened up at the southern end of the reservoir in the current aerial photo, but a $6.8 million voluntary effort to plug the hole with '4,000 cubic yards of concrete 400 feet beneath the surface through 50 grout injection casings' (source) has closed up the damage (zoom out to view 'Bone Valley,' the heart of Florida's phosphate industry that's distinguished from the rest of Florida's landscape by its light blue lagoons and snowy mountains of phosphate-waste.  From this waste, up to 75% of the U.S. uranium was extracted at one point during the beginning of the atomic age by the U.S. Atomic Energy Commission for nuclear bombs; it still remains a 'backup' supply of weapons-grade uranium but [Uranium-235] is very costly to extract.
  
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• The stacks include not only low-levels of radioactivity; according to U.S. News and World Report's 1995 article 'Sinkholes and Stacks': phosphogypsum 'is pumped from the fertilizer plants into the stacks in a slurry of waste water that is as acidic as gastric fluid or lemon juice. The effluent contains varying concentrations of 17 heavy metals or other toxic substances, including lead, arsenic, chromium, mercury and cadmium.'  In the mid-1990s, a new stack started growing a few hundred yards from a grade school!

• It has been U.S. companies - not Chinese ones - that since the 1970s have actually proposed and pushed the EPA to use the byproduct for use in anything from road construction to new plastic composites to roofing tiles to artificial coral reefs to pasture grass 'fertilizer'!   Why?  Look at the picture in the above link!  It is bad for the environment and bad for the phosphate industry's image.

• The EPA has prohibited reuse of phosphogypsum with radium 226 levels greater than 10 pCi/g of radium-226 and only allows reuse under that limit as an 'agricultural amendment.' The EPA allows northern Florida farmers to spread phosphogypsum on their farm fields that contains less than 10 pCi/g of radium-226!

• Mosaic ad campaign hides the truth about phosphate mining, 12/15/09

• There's a gypsum-coal plant connection: "Most of the byproduct gypsum used in North America to manufacture wallboard is produced when coal-fired power plants clean their stacks. Stack emissions are fed through a limestone slurry and oxygenated in a process that yields flue gas desulfurization gypsum. Wallboard-grade byproduct gypsum and natural gypsum are chemically identical." - All Things Gypsum: Chinese Drywall, Michael Gardner, November 4, 2009, wconline.com

• How phosphogypsum is made: fluorapatite (igneous) or francolite (sedimentary), both phosphate minerals, is extracted, mixed with water and sulfuric acid  to make phosphoric acid and waste-product phosphogypsum 

  Simplified equation:

  • Ca(PO4)2 + 3H2SO4 => 2H3PO4 + 3CaSO4 

  • (Sulfuric acid = H2SO4 ; Phosphoric acid = H3PO4 ; Phosphogypsum = CaSO4.2H2O)

   

• Phosphogypsum contains radium-226, uranium-238, thorium-234, protractinium-234, uranium-234, thorium-230, gaseous radon-222 (half-life of 3.8 days), polonium-218, lead-214, bismuth-214, polonium-214, lead-210, bismuth-210, polonium-210, and stable lead-206.

• Radium-226, which has phosphorescing qualities, used to be painted on watch dials to make them glow.  Unfortunately, factory workers thinly painting the radioactive radium on dials in the early part of the 20^th century licked their brushes and ingested dangerous amounts of radium into their bodies, leading to a slew of radiation-induced maladies, among them bloody gums - interestingly, one of the health problems associated with imported drywall is bloody noses.  (The radium paint comprised radium-226, which is an alpha emitter with a small beta and gamma ray component.) 

So, how would Strontium-90 get into drywall? 

Well, if you’ve ever cut open and looked at a cross-section of drywall, you’ll see ‘pores’, or air spaces.  Drywall is mostly made with gypsum, a mined mineral, which would be too heavy to use in construction for drywalls without processing.  During the drywall production process, gypsum is mixed with an assortment of ingredients (starch, paper pulp, water), but mostly air, which becomes about 50% of the final volume in drywall. This air makes drywall boards light in weight and easy to handle.  The problem is that Strontium-90 is in air all over the world from nuclear power plant production, nuclear weapons production and lingering nuclear testing fallout.  Products from manufacturing processes that incorporate large quantities of air in the final product, like drywall production and even steel-making through recent times, have higher concentrations of fallout radioisotopes in them than normal consumer products.  This is one hypothesis why drywall has detectable levels of Strontium-90.  If this hypothesis is correct, then one has to wonder what are the ambient Strontium-90 air concentrations in China that would lead to a consumer product ten times more radioactive than those produced in the United States.  

Another theory for the Strontium-90 in drywall has to do with 'isomorphic replacement.'  Isomorphic replacement is the replacement of one element in the chemical makeup of a mineral by another one (that has the same valence).  Isomorphic replacement is why any one group of gemstones can have a wide range of gemological properties and color variances!  For instance, a garnet that is created with manganese instead of calcium with be reddish instead of greenish!  This happens because the two chemicals are 'analogs.'  The same occurs with Strontium-90 in natural minerals containing calcium and magnesium.  When gypsum forms, it is usually rich in calcium(CaSO4, 2H2O), but lacking calcium it will take up Strontium-90, which has been in abundance in surface air around the globe since 1945 from nuclear testing and other nuclear activities.  However, it is likely that China is mining gypsum that's been in place for thousands of years, rather than from an evaporite lake-bed (gypsum can possibly form in mineable quantities in 60 years.)