Dichlorofluoromethane (Freon 21)
CAS No. 75-43-4

Return to Dichlorofluoromethane Adverse Effects

ACTIVITY: US EPA List 2 Inert, Propellant (Halogenated organic)


Adverse Effects:


Endocrine: Testicular

Environmental Effects:

Ozone depleting substance 

Regulatory Information
(only comprehensive for the US)
US EPA Registered: Yes
List 2 Inert
California Chemical Code 1815
Other Information
Manufacturers: DuPont
Other Names: Freon 21, CFC 21, Halon 112,
HCFC-21, Genetron 21,
Fluorihiili 21
Of special interest:
PAN Data
TOXNET profile from Hazardous Substances Data Bank
2000 - Toxic Release Inventory. Brief summary.

Rationale for US EPA to add Dichlorofluoromethane to the Toxic Release Inventory

Hydrochlorofluorocarbons are known to release chlorine radicals into the stratosphere. Chlorine radicals act as catalysts to reduce the net amount of stratospheric ozone.

Stratospheric ozone shields the earth from ultraviolet-B (UV-B) radiation (i.e., 290 to 320 nanometers). Decreases in total column ozone will increase the percentage of UV-B radiation, especially at its most harmful wavelengths, reaching the earth's surface.

Exposure to UV-B radiation has been implicated by laboratory and epidemiologic studies as a cause of two types of nonmelanoma skin cancers: squamous cell cancer and basal cell cancer. Studies predict that for every 1 percent increase in UV-B radiation, nonmelanoma skin cancer cases would increase by about 1 to 3 percent.

Recent epidemiological studies, including large case control studies, suggest that UV-B radiation plays an important role in causing malignant melanoma skin cancer. Recent studies predict that for each 1 percent change in UV-B intensity, the incidence of melanoma could increase from 0.5 to 1 percent.

Studies have demonstrated that UV-B radiation can suppress the immune response system in animals, and, possibly, in humans. Increases in exposure to UV-B radiation are likely to increase the incidence of cataracts and could adversely affect the retina.

Aquatic organisms, particularly phytoplankton, zooplankton, and the larvae of many fishes, appear to be susceptible to harm from increased exposure to UV-B radiation because they spend at least part of their time at or near the surface of waters they inhabit.

Increased UV-B penetration has been shown to result in adverse impacts on plants. Field studies on soybeans suggest that yield reductions could occur in some cultivars of soybeans, while evidence from laboratory studies suggest that two out of three cultivars are sensitive to UV-B.

Because this increased UV-B radiation can be reasonably anticipated to lead to cancer and other chronic human health effects and significant adverse environmental effects, EPA believes there is sufficient evidence for listing the following HCFCs that are commercially viable on EPCRA section 313 pursuant to EPCRA sections 313(d)(2)(B) and (C). EPA is proposing that the following HCFCs be added individually to EPCRA section 313:
Ref: USEPA/OPPT. Support Document for the Health and Ecological Toxicity Review of TRI Expansion Chemicals. U. S. Environmental Protection Agency, Washington, DC (1993). As cited by US EPA in: Federal Register: January 12, 1994. Part IV. 40 CFR Part 372. Addition of Certain Chemicals; Toxic Chemical Release Reporting; Community Right-to-Know; Proposed Rule.

US EPA List of Inerts. This substance is on List 2

Note: US EPA allows so-called "Inert" ingredients to be commonly mixed with the "active" pesticidal ingredient to create a formulated pesticide product. According to EPA, "The term `inert' is not intended to imply nontoxicity; the ingredient may or may not be chemically active." "Inert" ingredients include solvents, emulsifiers, spreaders, and other substances mixed into pesticide products to increase the effectiveness of the active ingredients, make the product easier to apply, or to allow several active ingredients to mix in one solution. Both US EPA and California Department of Pesticide Regulation require pesticide manufacturers to identify inert ingredients in their products but do not disclose this information to the general public because the pesticide industry considers product formulations trade secrets, protected by law and by the US EPA. The US EPA category of Inerts (as of September 2003):

List 1 - Of Toxicological Concern
List 2 - Potentially Toxic / High Priority for Testing
List 3 - Of Unknown Toxicity
List 4A - Generally Regarded as Safe
List 4B - EPA states it has Sufficient Information to Reasonably Conclude that the Current Use Pattern in Pesticide Products will not Adversely Affect Public Health or the Environment

See good report: Toxic Secrets": "Inert" Ingredients in Pesticides 1987-1997, published by Northwest Coalition for Alternatives to Pesticides.

US Federal Register
Date Published Docket Identification Number Details
June 21, 2001 RSPA-2000-7702 (HM-215D) Hazardous Materials Regulations for Fluoride/fluorinated substances. Harmonization of international shipment of Dangerous Goods. - FINAL RULE.
June 24, 1998 OPP- 36192 US EPA List 2 Inert; Ingredient in Pesticide Products.
Jan 12, 1994 OPPTS-400082 EPA's proposal to add 41 fluorine and organofluorine chemicals to the Toxics Release Inventory (TRI). See excerpt in box above. Also available at http://www.epa.gov/tri/frnotices/59fr1788.htm
Fluoride Action Network | Pesticide Project | 315-379-9200 | pesticides@fluoridealert.org