National Organic Standards Board

Crops Subcommittee

Petitioned Material Checklist - Calcium Sulfate (synthetic) 

January 6, 2015

Summary of Proposed Action:

The National Organic Standards Board (NOSB) received a petition from the American Coal Ash 

Association to add synthetic calcium sulfate (gypsum) to the National List of Approved Substances at

§205.601. This substance is also known as flue gas desulfurization (FGD) gypsum, with the source 

being the FGD systems installed to control sulfur dioxide emissions from coal-fired power plants.

Background:

The petition for calcium sulfate was sufficiently complete so that the subcommittee chose not to request 

a Technical Report. The petition raised two key points. First, FGD gypsum is a by-product of energy 

production and not all of this by product is able to be used. Thus, unused FDG gypsum ends up in 

landfills. Secondly, accessibility of mined gypsum in states where it is not mined is an important barrier 

for farmers, as it is difficult to acquire it at a reasonable price.

There is no doubt that the use of gypsum is beneficial for many soils and crops. It is a very abundant 

mined mineral, with mines in more than 20 states, and most mining concentrated in the western United 

States. Other non-synthetic substances can easily substitute for gypsum if necessary, including 

limestone, bone meal, and elemental sulfur, as well as organic matter from compost or cover cropping.

The petition states that the process used to produce FGD gypsum produces a relatively pure product, 

but it does not say what contaminants might be in the product. Meanwhile, an Environmental Protection 

Agency (EPA) factsheet says, “[T]he amount and types of trace materials and unreacted sorbents 

found in the gypsum can vary among power plants and among mines. If you are considering using FGD 

gypsum products as a soil amendment, it is appropriate that the chemical analysis of the material be 

provided by all commercial sources to support decision-making in their use, as States may have 

regulations and standards that need to be followed.” 1

 A study by the Electric Power Research Institute 

found the following elements in FGD gypsum in varying concentrations: aluminum, arsenic, boron, 

barium, beryllium, calcium, cadmium, cobalt, chromium, copper, iron, mercury, potassium, lithium, 

magnesium, manganese, molybdenum, sodium, nickel, phosphorus, lead, sulfur, tin, selenium, silicon, 

strontium, titanium, vanadium, and zinc.2

 

Based on this evidence demonstrating the potential for contamination, the NOSB, in following EPA’s 

recommendation, would need to specify allowable sources or allowable levels of contaminants if the 

Board chooses to approve the petition. Nevertheless, due to the many alternatives to synthetic gypsum

that exist, the subcommittee believes that it is not essential for organic farming and that this criterion

out-weighs the recycling benefits that are associated with the use of FGD gypsum.

1 EPA factsheet, Agricultural Uses for Flue Gas Desulfurization (FGD) Gypsum. 

http://nepis.epa.gov/Exe/ZyPDF.cgi/P1001II9.PDF?Dockey=P1001II9.PDF

2 Electric Power Research Institute, 2011. Composition and Leaching of FGD Gypsum and Mined Gypsum. (p.A-1, 2; p.33-

34)

http://www.epri.com/abstracts/Pages/ProductAbstract.aspx?ProductId=000000000001022146 

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Evaluation Criteria 

 Criteria Satisfied? 

1. Impact on Humans and Environment ☒ Yes ☐ No ☐ N/A 

2. Essential & Availability Criteria ☐ Yes ☒ No ☐ N/A

3. Compatibility & Consistency ☐ Yes ☒ No ☐ N/A 

Substance Fails Criteria Category: 2, 3 

Subcommittee Action & Vote

Classification Motion: Motion to classify Calcium Sulfate, produced by the flue gas desulfurization 

(FGD) process as petitioned as synthetic 

Motion by: Zea Sonnabend 

Seconded by: Harold Austin

Yes: 6 No: 0 Abstain: 0 Absent: 1 Recuse: 0

Listing Motion: Motion to add Calcium Sulfate, produced by the flue gas desulfurization (SGD) 

process as petitioned to 205.601 

Motion by: Zea Sonnabend 

Seconded by: Harold Austin

Yes: No: 6 Abstain: 0 Absent: 1 Recuse: 0

 Proposed Annotation (if any): none

Approved by Zea Sonnabend, Subcommittee Chair, to transmit to NOSB January 6, 2015

NOSB Evaluation Criteria for Substances Added To the National List - Crops

Category 1. Adverse impacts on humans or the environment? Calcium Sulfate - synthetic 

Question Yes No N/A Comments/Documentation (TAP; 

petition; regulatory agency; other)

1. Is there a probability of environmental 

contamination during use or misuse? 

[§6518(m)(3)]

X This substance helps prevent 

environmental contamination from 

industrial pollution.

2. Is there a probability of environmental 

contamination during, manufacture or 

disposal? [§6518(m)(3)]

X

3. Are there any adverse impacts on 

biodiversity? (§205.200)

X

4. Does the substance contain inerts 

classified by EPA as ‘inerts of 

toxicological concern’? [§6517 

(c)(1)(B)(ii)]

X

5. Is there potential for detrimental chemical 

interaction with other materials used in 

X

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organic farming systems?

[§6518(m)(1)]

6. Is there a toxic or other adverse action of 

the material or its breakdown products?

[§6518(m)(2)]

X See page 1, paragraph 4.

7. Is there persistence or concentration of 

the material or breakdown products in 

the environment? [§6518(m)(2)]

X

8. Would the use of the substance be 

harmful to human health or the 

environment? [§6517 (c)(1)(A)(i); §6517 

(c)(2)(A)(i); §6518(m)(4)]

X “Studies of gypsum mine workers have 

reported no lung fibrosis or 

pneumoconiosis...” (from NIEHS report 

included with the petition, page 21).

9. Are there adverse biological and 

chemical interactions in the agroecosystem? [§6518(m)(5)]

X

10. Are there detrimental physiological 

effects on soil organisms, crops, or 

livestock? [§6518(m)(5)]

X

Category 2. Is the Substance Essential for Organic Production? Calcium Sulfate - synthetic 

Question Yes No N/A Comments/Documentation (TAP; 

petition; regulatory agency; other)

1. Is the substance agricultural? [§6502(1)] X

2. Is the substance formulated or 

manufactured by a chemical process? 

[§6502(21)]

X

3. Is the substance formulated or 

manufactured by a process that 

chemically changes a substance 

extracted from naturally occurring plant, 

animal, or mineral sources? 

[§6502(21)]

X

4. Is the substance created by naturally 

occurring biological processes? 

[§6502(21)]

X

5. Is there a natural source of the 

substance? [§ 205.600(b)(1)]

X There is abundant nonsynthetic gypsum.

6. Is there an organic substitute? 

[§205.600(b)(1)]

X

7. Is there a wholly natural substitute 

product?

[§6517(c)(1)(A)(ii)]

X mined gypsum, limestone, bone meal

8. Are there any alternative substances? 

[§6518(m)(6)]

X see above

9. Are there other practices that would 

make the substance unnecessary? 

[§6518(m)(6)]

X Compost and cover cropping can have a 

positive effect on soils and provide some 

calcium and sulfur.

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NOSB Evaluation Criteria for Substances Added To the National List - Crops

Category 3. Is the substance compatible with organic production practices? Calcium Sulfate - 

synthetic:

Question Yes No N/A Comments/Documentation (TAP; 

petition; regulatory agency; other)

1. Is the substance consistent with organic 

farming and handling? 

[§6517(c)(1)(A)(iii); 6517(c)(2)(A)(ii)]

X Organic farming regulations and 

philosophy favor using non-synthetic 

substances when available over 

synthetic.

2. Is the substance compatible with a 

system of sustainable agriculture? 

[§6518(m)(7)] 

X Because ample non-synthetic gypsum is 

available, and price and convenience are 

not among the evaluation criteria, this 

substance does not appear to be 

compatible.

3. If used in livestock feed or pet food, is 

the nutritional quality of the food 

maintained with the substance? 

[§205.600(b)(3)]

X

4. If used in livestock feed or pet food, is 

the primary use as a preservative? 

[§205.600(b)(4)]

X

5. If used in livestock feed or pet food, is 

the primary use to recreate or improve 

flavors, colors, textures, or nutritive value 

lost in processing (except when required 

by law)? [§205.600(b)(4)]

X

6. Is the substance used in production, and 

does it contain an active synthetic 

ingredient in the following categories:

[§6517(c)(1)(B)(i);

copper and sulfur compounds

X

toxins derived from bacteria X

pheromones, soaps, horticultural oils, 

fish emulsions, treated seed, vitamins 

and minerals

X

livestock parasiticides and medicines X

production aids including netting, tree 

wraps and seals, insect traps, sticky 

barriers, row covers, and equipment 

cleansers

X

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