Registration Decision RD2010-12, Oxalic Acid Dihydrate

17 November 2010
HC Pub: 100517
ISBN: 978-1-100-16852-4 (print version)
ISBN: 978-1-100-16853-1 (PDF version)
Catalogue number: H113-25/2010-15E (print version)
Catalogue number: H113-25/2010-15E-PDF (PDF version)

Help on accessing alternative formats, such as Portable Document Format (PDF), Microsoft Word and PowerPoint (PPT) files, can be obtained in the alternate format help section.

Table of Contents

• Registration Decision for Oxalic Acid Dihydrate
• What Does Health Canada Consider When Making a Registration Decision?
• What Is Oxalic Acid Dihydrate?
• Health Considerations
• Environmental Considerations
• Value Considerations
• Measures to Minimize Risk
• Other Information
• Appendix I - Comments
• References

Registration Decision for Oxalic Acid Dihydrate

Health Canada's Pest Management Regulatory Agency (PMRA), under the authority of the Pest Control Products Act, and Regulations, is granting full registration for the sale and use of Oxalic Acid Dihydrate Technical and Oxalic Acid Dihydrate, containing the technical grade active ingredient oxalic acid dihydrate to control Varroa mites in honeybee colonies.

An evaluation of available scientific information found that, under the approved conditions of use, the product has value and does not present an unacceptable risk to human health or the environment.

These products were first proposed for registration in the consultation document^{Footnote 1} : Proposed Registration Decision PRD2010-12 - Oxalic Acid Dihydrate. This Registration Decision^{Footnote 2} describes this stage of the PMRA's regulatory process for oxalic acid dihydrate and summarizes the Agency's decision, the reasons for it and provides, in Appendix I, a summary of comments received during the consultation process as well as the PMRA's response to these comments. This decision is consistent with the proposed registration decision stated in PRD2010-12.

For more details on the information presented in this Registration Decision, please refer to the Proposed Registration Decision PRD2010-12 - Oxalic Acid Dihydrate that contains a detailed evaluation of the information submitted in support of this registration.

What Does Health Canada Consider When Making a Registration Decision?

The key objective of the Pest Control Products Act is to prevent unacceptable risks to people and the environment from the use of pest control products. Health or environmental risk is considered acceptable^{Footnote 3} if there is reasonable certainty that no harm to human health, future generations or the environment will result from use or exposure to the product under its conditions of registration. The Act also requires that products have value^{Footnote 4} when used according to label directions. Conditions of registration may include special precautionary measures on the product label to further reduce risk.

To reach its decisions, the PMRA applies modern, rigorous risk-assessment methods and policies. These methods consider the unique characteristics of sensitive subpopulations in humans (for example children) as well as organisms in the environment (for example those most sensitive to environmental contaminants). These methods and policies also consider the nature of the effects observed and the uncertainties when predicting the impact of pesticides. For more information on how the PMRA regulates pesticides, the assessment process and risk-reduction programs, please visit the PMRA's website at healthcanada.gc.ca/pmra.

What Is Oxalic Acid Dihydrate?

Oxalic Acid Dihydrate is a dicarboxylic acid, which is a relatively strong organic acid. Oxalic Acid Dihydrate is used in honeybee colonies to control Varroa mites using two different application methods, as a solution by the trickle treatment method, and as a solid by the vaporisation method. Applications are made in the late fall to early spring, when little to no brood is present in the hive and honey supers are not in place.

While the mode of action of Oxalic Acid Dihydrate is not entirely understood, it appears to be mainly due to the low pH of the acid, which results in contact toxicity (physical injury of mites due to low pH). With the trickle-method of application, Oxalic Acid Dihydrate is dissolved into a 1:1 sugar:water solution, which is directly applied to the infested bees. The bees can tolerate the concentration of oxalic acid in the applied solution, but the Varroa mites cannot. With the vaporisation method of application, Oxalic Acid Dihydrate crystals are heated using a specialized application device until they liquefy and vaporise. Oxalic acid vapour fills the hive and all the bees and hive interior surfaces are covered with a very thin layer of Oxalic Acid Dihydrate crystals. While these fine crystals are tolerated by the bees, they are toxic to the Varroa mites.

Health Considerations

Can Approved Uses of Oxalic Acid Dihydrate Affect Human Health?

Oxalic Acid Dihydrate is unlikely to affect your health when used according to label directions.

Exposure to oxalic acid dihydrate may occur when handling and applying the end-use product, Oxalic Acid Dihydrate. When assessing health risks, two key factors are considered: the levels where no health effects occur and the levels to which people may be exposed. The dose levels used to assess risks are established to protect the most sensitive human population (for example children and nursing mothers). Only uses for which the exposure is well below levels that cause no effects in animal testing are considered acceptable for registration.

Since the technical grade active ingredient, oxalic acid dihydrate, is highly acutely toxic and corrosive to both the eye and skin, the statements, "DANGER - POISON", "DANGER - CORROSIVE TO EYES", and "DANGER - SKIN IRRITANT" have been included on the principal display panel of the general label and AFatal or poisonous if swallowed", "DO NOT get in eyes", "CORROSIVE to the eyes", "DO NOT get on skin or clothing", "Corrosive to the skin", and "Avoid inhaling/breathing dust or fumes" have been included in the PRECAUTIONS section of the secondary display panel of the general label.

Residues in Water and Food

Dietary risks from food and water are not of concern.

It is anticipated that the amount of oxalic acid dihydrate present as a residue after application of the end-use product will not likely exceed the range of naturally occurring concentrations found in honey or vegetables. The direct application of oxalic acid dihydrate to beehives means that exposure to sources of drinking water will be negligible. Therefore, the use of oxalic acid dihydrate is not expected to result in dietary risk from food and/or water.

Occupational Risks From Handling Oxalic Acid Dihydrate

Occupational risks are not of concern when Oxalic Acid Dihydrate is used according to label directions, which include protective measures.

Pesticide applicators handling and applying Oxalic Acid Dihydrate to bee hives, can come in direct contact with oxalic acid dihydrate on the skin and in the eyes, as well as by accidental ingestion and inhalation. The current label statements adequately mitigate the concern of exposure to the applicators.

It is expected that only workers will be permitted access to the treated areas, thus the potential for bystander exposure is expected to be minimal and not of concern.

Environmental Considerations

What Happens When Oxalic Acid Dihydrate Is Introduced Into the Environment?

Oxalic acid is a naturally occurring compound that transforms rapidly under environmental conditions. Exposure of the chemical to the environment is expected to be limited during the use of Oxalic Acid Dihydrate for control of Varroa mite in beehives. The product is applied as a liquid or vapour to an affected colony; environmental exposure would occur primarily through spillage or leakage during application. Based on limited exposure, the chemical's natural occurrence and the likelihood for relatively rapid transformation under environmental conditions, the proposed use of Oxalic Acid Dihydrate is not expected to pose a significant risk to the environment. Therefore, further review of the environmental chemistry, fate, and toxicology of Oxalic Acid Dihydrate was not considered necessary.

Value Considerations

What Is the Value of Oxalic Acid Dihydrate?

Oxalic Acid Dihydrate has value for control of Varroa mite in honeybee colonies. Evaluated data demonstrated that Oxalic Acid Dihydrate can provide 90-99% control of Varroa mites in honeybee colonies when either the trickle treatment or vaporisation application methods are used when little to no honeybee brood is present in the hives (for example late fall to early spring).

Measures to Minimize Risk

Labels of registered pesticide products include specific instructions for use. Directions include risk-reduction measures to protect human and environmental health. These directions must be followed by law.

The key risk-reduction measures being proposed on the labels of Oxalic Acid Dihydrate Technical and Oxalic Acid Dihydrate to address the potential risks identified in this assessment are as follows.

Key Risk-Reduction Measures

Human Health

Because there is a possibility of accidental oral, dermal, and inhalation exposure by workers, individuals should observe all precautionary and first aid statements on the product label. The  label-required wearing of personal protective equipment by workers and the requirement to conduct activities in well ventilated areas are expected to minimize the potential for exposure to oxalic acid dihydrate. Based on the limited use pattern to bee hives, bystanders are not expected to be exposed to oxalic acid dihydrate.

Environment

No environmental risk-reduction measures are required. Standard label statements to protect the environment are required.

Other Information

1. The relevant test data on which the decision is based (as referenced in this document) are available for public inspection, upon application, in the PMRA's Reading Room (located in Ottawa). For more information, please contact the PMRA's Pest Management Information Service by phone (1-800-267-6315) or by e-mail (pmra.inforserv@hc-sc.gc.ca)
2. Any person may file a notice of objection^{Footnote 5} regarding this registration decision within 60 days from the date of publication of this Registration Decision. For more information regarding the basis for objecting (which must be based on scientific grounds), please refer to the PMRA's website (Requesting a Reconsideration of Decision, healthcanada.gc.ca/pmra) or contact the PMRA's Pest Management Information Service by phone (1-800-267-6315) or by e-mail (pmra.inforserv@hc-sc.gc.ca).

Appendix I - Comments

1. Two comments were received from beekeepers which supported the registration of oxalic acid dihydrate as a useful tool in managing Varroa mites in honeybee colonies.

References

A. List of Studies/Information Submitted by Registrant

1.0 Chemistry

TGAI

PMRA Document Number: 966154
Reference: CHEMINFO: Oxalic Acid. www.intox.org/databank/documents/chemical/oxalicac/cie358.htm Retrieved: August 27, 2004. 13pp. Published, DACO:2.14.1, 2.14.2, 2.14.3, 2.14.4, 2.14.5, 2.14.6, 2.14.7, 2.14.8, 2.14.9, 2.3.1, 2.4, 2.5, 2.6, 2.7, 2.8, 3.1.4, 3.5.1, 3.5.10, 3.5.11, 3.5.14, 3.5.2, 3.5.3, 3.5.6, 3.5.7, 3.5.8, 3.5.9, 4.1, 4.2.1, 4.2.4, 4.2.6, 4.4.2, 4.4.3, 4.6 CBI

PMRA Document Number: 966156
Reference: Hazardous Substances Databank: Oxalic Acid. www.ccohs.ca. Retrieved June 28, 2004. 23pp. Published, DACO: 2.14.10, 2.14.11, 2.14.13, 2.14.14, 2.3.1, 4.4.1, 8.1, 8.2.1, 8.2.2.1, 8.4.1, 9.1 CBI

PMRA Document Number: 966159
Reference: Reregistration Eligibility Document. www.epa.gov/oppsrrd1/REDs/old_reds/oxalic_acid.pdf Retrieved June 28, 2004. Environmental Protection Agency, United States of America. 58pp Published, DACO: 12.5.4, 12.5.8, 12.7, 2.11.1, 2.11.2, 2.11.3, 3.2.1, 4.1, 4.2.1, 4.2.3, 4.3.2, 4.3.5, 4.4.1, 4.5.1, 4.5.2, 4.5.9, 4.6.3, 4.7, 7.2.4, 8.1 CBI

PMRA Document Number: 1263986
Reference: Process for the Preparation of Oxalic Acid and Sodium Hydrogen Oxalate from Crude Sodium Oxalate. Canadian Patent 1314905, DACO: 2.11.1, 2.11.2, 2.11.3 CBI

PMRA Document Number: 1263987
Reference: Certificate of Analysis. www.univarcanada.com Retrieved June 20, 2004. 1p., DACO: 2.11.4, 2.12.1, 2.13.3 CBI

PMRA Document Number: 1263988
Reference: Specification Sheet. www.univarcanada.com Retrieved June 20, 2004. 1p., DACO: 2.12.2, 2.15 CBI

PMRA Document Number: 1263989
Reference: 2001, Sodium Hydroxide Titrations: Standard Operating Procedure; Quality Control. Sigma Aldrich, Sheboygan Canada, DACO: 2.13.1, 2.13.2 CBI

PMRA Document Number: 1263990
Reference: 2000, Nicolet Avatar ESP ESP FT-IR Sample Analysis; Quality Control. Sigma Aldrich, Sheboygan Canada, DACO: 2.13.2 CBI

PMRA Document Number: 1263991
Reference: 2002, Melting Point Apparatus (Thomas Hoover Unimelt); Quality Control. Sigma Aldrich, Sheboygan Canada, DACO: 2.13.2 CBI

PMRA Document Number: 1263992
Reference: Jeanette G. Grasselli, Atlas Of Spectral Data and Physical Constants for Organic Compounds. CRC Press. Clevland, USA. P. B716, DACO: 2.14.12, 8.2.1 CBI

PMRA Document Number: 1622413
Reference: certificate of analysis, DACO: 2.13.3 CBI

PMRA Document Number: 1622414
Reference: certificate of analysis, DACO: 2.13.3 CBI

PMRA Document Number: 1622415
Reference: certificate of analysis, DACO: 2.13.3 CBI

PMRA Document Number: 1622416
Reference: certificate of analysis, DACO: 2.13.3 CBI

PMRA Document Number: 1622417
Reference: certificate of analysis, DACO: 2.13.3 CBI

PMRA Document Number: 1658807
Reference: 2008, 5 Batch Data, DACO: 2.13.3

EP

PMRA # - Reference

PMRA Document Number: 966154
Reference: CHEMINFO: Oxalic Acid. www.intox.org/databank/documents/chemic al/oxalicac/cie358.htm Retrieved: August 27, 2004. 13pp. Published, DACO: 2.14.1, 2.14.2, 2.14.3, 2.14.4, 2.14.5, 2.14.6, 2.14.7, 2.14.8, 2.14.9, 2.3.1, 2.4, 2.5, 2.6, 2.7, 2.8, 3.1.4, 3.5.1, 3.5.10, 3.5.11, 3.5.14, 3.5.2, 3.5.3, 3.5.6, 3.5.7, 3.5.8, 3.5.9, 4.1, 4.2.1, 4.2.4, 4.2.6, 4.4.2, 4.4.3, 4.6 CBI

PMRA Document Number: 966159
Reference: Reregistration Eligibility Document. http://www.epa.gov/oppsrrd1/REDs/old_reds/oxalic_acid.pdf Retrieved June 28, 2004. Environmental Protection Agency, United States of America. 58pp Published, DACO: 12.5.4, 12.5.8, 12.7, 2.11.1, 2.11.2, 2.11.3, 3.2.1, 4.1, 4.2.1, 4.2.3, 4.3.2, 4.3.5, 4.4.1, 4.5.1, 4.5.2, 4.5.9, 4.6.3, 4.7, 7.2.4, 8.1 CBI

PMRA Document Number: 966029
Reference: Process For The Preparation Of Oxalic Acid And Sodium Hydrogen Oxalate From Crude Sodium Oxalate. Canadian Patents Database. Patent No CA 1314905. Published, DACO: 3.2.2 CBI

PMRA Document Number: 966030
Reference: Certificate of Analysis. www.univarcanada.com Retrieved Nov 20, 2004. 1p. Not Published, DACO: 3.2.3, 3.5.4 CBI

PMRA Document Number: 966031
Reference: Specification Sheet. www.univarcanada.com Retrieved Nov 20, 2004. 1p. Not Published, DACO: 3.3.2 CBI

PMRA Document Number: 966032
Reference: Sodium Hydroxide Titrations: Standard Operating Procedure; Quality Control. 3pp. Published, DACO: 3.4.1 CBI

PMRA Document Number: 966036
Reference: Storage of Oxalic Acid Sucrose Solution. 3pp. Published, DACO: 3.5.10, 7.2.5, 7.3

PMRA Document Number: 966025
Reference: Hazardous Substances Databank: Oxalic Acid. www.ccohs.ca. Retrieved June 28, 2004. 23pp. Published, DACO: 5.1, 5.3

2.0 Human and Animal Health

PMRA # - Reference

PMRA Document Number: 966154
Reference: CHEMINFO: Oxalic Acid. www.intox.org/databank/documents/chemic al/oxalicac/cie358.htm Retrieved: August 27, 2004. 13pp. Published, DACO: 2.14.1, 2.14.2, 2.14.3, 2.14.4, 2.14.5, 2.14.6, 2.14.7, 2.14.8, 2.14.9, 2.3.1, 2.4, 2.5, 2.6, 2.7, 2.8, 3.1.4, 3.5.1, 3.5.10, 3.5.11, 3.5.14, 3.5.2, 3.5.3, 3.5.6, 3.5.7, 3.5.8, 3.5.9, 4.1, 4.2.1, 4.2.4, 4.2.6, 4.4.2, 4.4.3, 4.6 CBI

PMRA Document Number: 966156
Reference: Hazardous Substances Databank: Oxalic Acid. www.ccohs.ca. Retrieved June 28, 2004. 23pp. Published, DACO: 2.14.10, 2.14.11, 2.14.13, 2.14.14, 2.3.1, 4.4.1, 8.1, 8.2.1, 8.2.2.1, 8.4.1, 9.1 CBI

PMRA Document Number: 966159
Reference: Reregistration Eligibility Document. http://www.epa.gov/oppsrrd1/REDs/old_reds/oxalic_acid.pdf Retrieved June 28, 2004. Environmental Protection Agency, United States of America. 58pp Published, DACO: 12.5.4, 12.5.8, 12.7, 2.11.1, 2.11.2, 2.11.3, 3.2.1, 4.1, 4.2.1, 4.2.3, 4.3.2, 4.3.5, 4.4.1, 4.5.1, 4.5.2, 4.5.9, 4.6.3, 4.7, 7.2.4, 8.1 CBI

PMRA Document Number: 966165
Reference: Oxalic acid residues in honey. Melliferae.V, lmkerei Fischermühle, 72348 Rosenfeld, Germany. 2pp. Published, DACO: 4.1, 7.4, 7.4.1

PMRA Document Number: 966166
Reference: Determination of residues in honey after treatments with formic and oxalic acid under field conditions. Apidologie 33:399- 409. Published, DACO: 4.1, 7.4

PMRA Document Number: 966167
Reference: Health-based Reassessment of Administrative Occupational Exposure Limits: Oxalic Acid. The Hague, Health Council of the Netherlands, Netherlands. 18pp. Published, DACO: 4.1, 4.2.1, 4.2.3, 4.2.5, 4.3.1, 4.3.5, 4.4.1, 4.5.1, 4.5.6, 4.6.1, 4.6.2, 4.6.3, 4.6.5, 4.7.1

PMRA Document Number: 966168
Reference: Oxalic Acid Content of Selected Vegetables. In Agricultural Handbook No 8-11: Vegetables and Vegetable Products. USDA, United States of America. 2pp. Published, DACO: 4.1, 4.4.2, 4.4.3

PMRA Document Number: 966169
Reference: Nanetti, A. et al., 2003, Oxalic Acid Treatments for Varroa Control (Review), Apiacta 38:81-87, DACO: 12.5.8, 12.7

PMRA Document Number: 966170
Reference: 2001, New Zealand Ministry Agriculture and Forestry, Oxalic Acid Registration Submission for Varroa Control. NZMAF. Wellington NZ pp 21, DACO: 12.5.8

3.0 Environment

PMRA Document Number: 966154
Reference: CHEMINFO: Oxalic Acid. www.intox.org/databank/documents/chemic al/oxalicac/cie358.htm Retrieved: August 27, 2004. 13pp. Published, DACO:2.14.1, 2.14.2, 2.14.3, 2.14.4, 2.14.5, 2.14.6, 2.14.7, 2.14.8, 2.14.9, 2.3.1, 2.4, 2.5, 2.6, 2.7, 2.8, 3.1.4, 3.5.1, 3.5.10, 3.5.11, 3.5.14, 3.5.2, 3.5.3, 3.5.6, 3.5.7, 3.5.8, 3.5.9, 4.1, 4.2.1, 4.2.4, 4.2.6, 4.4.2, 4.4.3, 4.6 CBI

4.0 Value

PMRA # - Reference

PMRA Document Number: 966043
Reference: Évaluation de l acide oxalique et de l acide formique en traitement du Varroa destructor pendant la période estivale. Centre de recherche en sciences animales de Deschambault, Quebec. 29 pp. Published, DACO: 4.1, 7.4.1, 10.2.3.2

PMRA Document Number: 966056
Reference: Varroa control with oxalic acid: a new application. In Proceedings of European Working Group for Integrated Varroa Control, Bern, Switzerland, June 16, 2000. 6pp. Published, DACO: 5.2, 10.2.3.1

PMRA Document Number: 966058
Reference: Oxalic acid treatment by trickling: field against Varroa destructor:recommendations for use in Central Europe and under temperate conditions. Bee World 83(2):51- 60. Published, DACO: 10.2.3.1, 10.2.3.3, 12.7

PMRA Document Number: 966060
Reference: Drip treatment with oxalic acid: tests 1999/2000 and recommendations for use in central Europe. Swiss Bee Research Centre, Liebefeld, Switzerland. 10pp. Published, DACO: 10.2.3.1, 10.2.3.3

PMRA Document Number: 966061
Reference: Alternative Strategy in Central Europe for the Control of Varroa destructor in honeybee colonies. Apiacta 38:258-285: Published, DACO: 10.2.3.1, 10.2.3.3

PMRA Document Number: 966062
Reference: Acaricidal effect of oxalic acid in honeybee(Apis mellifera) colonies. Apidologie 32: 333 340. Published, DACO: 10.2.3.3

PMRA Document Number: 966063
Reference: Efficacy and tolerability of an oxalic acid trickling treatment. In Proceedings of European Working Group for Integrated Varroa Control, Bern, Switzerland, June 16, 2000. 2pp Published, DACO: 10.2.3.3

PMRA Document Number: 966064
Reference: Vaporization of oxalic acid in a field trial with 1509 colonies. Presentation to European Working Group for Integrated Varroa Control, York UK June 2001.9pp, DACO: 10.3.2

PMRA Document Number: 966067
Reference: Oxalic Acid in Varroa Control. An overview of the last five years of experiments. Istituto Nazionale di Apicoltura. Bologna, Italy. 5pp. Published, DACO:10.2.3.1, 10.2.3.3

PMRA Document Number: 966070
Reference: Oxalic Acid Efficacy Against Varroa Mites in the Fall. 2002 and 2003. Ontario Tech Transfer Program, OBA. Guelph, Ontario, 7 pp. Published, DACO:5.2, 10.2.3.1, 10.2.3.3

PMRA Document Number: 966072
Reference: Late Fall Efficacy of Oxalic Acid on Varroa Mites in Honeybee Colonies. 2001 and 2002 Trials. Ontario Tech Transfer Program, OBA, Guelph Ontario 4 pp. unpublished, DACO: 5.2, 10.2.3.1, 10.2.3.3

PMRA Document Number: 966074
Reference: Efficacy of Three Miticides (Oxalic acid, Formic acid. Apilife Var) on Varroa destructor and Acarapsis woodi in Honeybee Colonies in Canada. 8th European Meeting on integrated Varroa Control, Kirchain Germany-22-23May 2003, DACO: 5.2, 10.2.3.1

PMRA Document Number: 966469
Reference: Efficacy of Three Miticides (Oxalic acid, Formic acid. Apilife Var) on Varroa destructor in Honeybee Colonies in Alberta. American Bee Journal. Submitted, DACO: 5.2, 10.2.3.1, 10.2.3.3

B. Additional Information Considered

i) Published Information

1.0 Human and Animal Health

PMRA Document Number: 1810547
Reference: C. Curtin et al., 1955, The Metabolism of Ascorbic Acid-1-C and Oxalic Acid-C In the Rat, DACO: 4.5.9

PMRA Document Number: 1810554
Reference: 2004 TLVs and BEIs - Threshold Limit Values for Chemical Substances and Physical Agents & Biological Exposure Indices, DACO: 4.8

PMRA Document Number: 1810556
Reference: 2003, The European Agency for the Evaluation of Medicinal Products, Committee for Veterinary Medicinal Products - Oxalic Acid Summary Report, DACO: 4.8

PMRA Document Number: 1810564
Reference: M. Grant, 1962, Toxicology of the Eye, DACO: 4.8

PMRA Document Number: 1810573
Reference: G. Hathaway et al., 1966, Chemical Hazards of the Workplace, DACO: 4.8

PMRA Document Number: 1810577
Reference: M. Goldman et al., 1977, Effect of Dietary Ingestion of Oxalic Acid on Growth and
Reproduction in Male and Female Long-Evans Rats, DACO: 4.3.1

PMRA Document Number: 1810581
Reference: E.H. Vernot et al., 1977, Acute Toxicity and Skin Corrosion Data for Some Organic and Inorganic Compounds and Aqueous Solutions, DACO: 4.8

PMRA Document Number: 1810584
Reference: G. Clayton, 1982, Patty's Industrial Hygiene and Toxicology, DACO: 4.8

2.0 Value

Stanghellini and Raybold, Evaluation of selected biopesticides for the late fall control of Varroa mites in a northern temperate climate. American Bee Journal, 144:6, 2004, pp. 475-487.