Research of FDA about ClO2

This Environmental Assessment (EA) is intended to demonstrate that the proposed use of this FCS will not cause significant effects to the environment. The Notifier—Selective Micro Technologies (or SMT)—has a patented technology which ensures the controlled generation of chlorine dioxide gas upon the addition of water. Chlorine dioxide gas is generated through the use of our patented, specially-manufactured micro-reactor membrane technology. Inside this micro-reactor, compartmentalized precursor chemicals react to generate nearly-pure chlorine dioxide gas into a surrounding vessel of water. Nearly all the impurities resulting from the generation of the gas are retained safely inside the Selective Micro Technologies micro-reactor, meaning that a safe, uniform flow of chlorine dioxide gas is generated from the reaction inside the micro-reactor.

To generate chlorine dioxide gas, an SMT product-specific micro-reactor will either be immersed in a vessel of water or will be inside a dry, empty vessel to which water is to be added. Chlorine dioxide gas will generate according to the methods described in Section 4(c) of this document. Once the gas is generated into the water immersing the SMT micro-reactor, that gas will immediately begin to volatize into the surrounding air. Chlorine dioxide gas will be generated according to directions on the product label at a 3 ppm in-air residual. The chlorine dioxide gas will act as an oxidizer and reduce levels of bacteria and other microbes on the surface of fruits, vegetables, and RACs.

In-air levels of ClO₂ gas should be monitored using a Model C16 PortaSens II chlorine dioxide gas leak detector (or an equivalent measuring instrument). The reaction should be constantly monitored until the ClO₂ gas generates at a 3 ppm residual in-air. To obtain higher ClO₂ gas residuals, increase the concentration of the liquid ClO₂ solution generated in the reaction vessel or decrease the area that the gas is to treat. To generate lower ClO₂ gas residuals, dilute the liquid ClO₂ solution generated in the reaction vessel or increase the area that the gas is to treat. Once the generation reaction yields ClO₂ gas at a constant 3 ppm residual in-air, use the ClO₂ gas for fumigation applications as described on the product label. Check levels of ClO₂ gas at every fifteen minutes to ensure that the reaction maintains its 3 ppm in-air residual.

• Locations of use/disposal.

The FCS will treat fruits and vegetables in darkened, oxidation-resistant, sealed containers. This treatment will occur at plants, food processing facilities, warehouses, and distribution centers. The majority of this ClO₂ gas will be consumed in antibacterial fumigation reactions with organic matter. The remainder will be released to the atmosphere upon completion of the treatment.

There are two ways to use a Selective Micro Technologies micro-reactor to generate ClO₂ gas:

Place the micro-reactor in a vessel of water. Water vapor will then enter the micro-reactor.

Through osmotic force, chlorine dioxide gas is released from the micro-reactor into the vessel of water. The resulting chlorine dioxide solution is sparged, atomized or used as a fumigant to apply gaseous ClO₂ to fruits and vegetables inside a darkened, UV and oxidation-resistant, sealed container.

A – Selective Micro Technologies micro-reactor is placed in solution
B – ClO₂ is generated into solution
C – ClO₂ is released as a gas from the agitated solution

Alternatively, tap water can be added to a vessel of water with the micro-reactor already placed inside. Through osmotic force, only chlorine dioxide gas will be released from the micro-reactor into the water. The resulting chlorine dioxide solution is sparged, atomized or used as a fumigant to apply chlorine dioxide gas to fruits and vegetables inside a darkened, UV and oxidation-resistant, sealed container.

A – Tap water is added to vessel containing Selective Micro Technologies micro- reactor
B – ClO₂ is generated into solution
C – ClO₂ is released as a gas from the agitated solution

Regardless of the method used to generate ClO₂ gas, the micro-reactor will be disposed of after use according to directions on the label. The chlorine dioxide solution generated in the reaction vessel is to be diluted to a concentration of no more than 0.25 ppm ClO₂ and released to a wastewater stream.

Regardless of which method is employed, when the ClO₂ generation reaction is complete, food-grade citric acid is the only ingredient remaining inside the micro-reactor. As it comes into contact with food surfaces, chlorine dioxide gas will be consumed by the oxidation of organic matter and micro- organisms present on food. Unlike chlorine dioxide gas in-solution, which decomposes into various oxychloro species upon its exposure to water, gaseous chlorine dioxide will decompose into only chlorine and oxygen when released to the atmosphere.

• Disposal – Air.
  The generated chlorine dioxide gas is meant to fumigate fruits and vegetables in darkened, oxidation- resistant, sealed containers at a residual of 3 ppm. When treatment of the fruits and vegetables is complete, any remaining levels of chlorine dioxide can be released into the atmosphere via a controlled air flush.

• Disposal – Water.
  Upon completion of use, the solution is to be diluted until its concentration is at or less than 0.25 ppm chlorine dioxide in-solution. The concentration of the chlorine dioxide molecule can be measured with Selective Micro® Chlorine Dioxide Test Strips or an equivalent tool that is able to accurately measure levels of chlorine dioxide in a solution. Once the solution has been diluted to a concentration of 0.25 ppm, the expected route of disposal for process water from these facilities is via discharge to a local Publicly-Owned Treatment Works (POTW), an on-site wastewater treatment system, or directly into a natural body of water or a man-made depository channeling into a natural body of water (if the depositor has an NPDES permit for point-source discharge into open water).
  Upon the FCS’s discharge directly into a natural body of water or man-made depository channeling into a natural body of water, chlorine dioxide undergoes a reduction to chloride, chlorite, and chlorate ions upon exposure to organic matter. Additionally, chlorine dioxide often reduces to chlorine and oxygen when exposed to ultraviolet radiation and that from there is likely to degrade into chloride ions. Therefore, the Notifier considers a release of the FCS into an aquatic environment in any significant concentration extraordinarily unlikely due to its probable removal from the wastewater pathway either through reactions resulting from the FCS’s contact with organic matter, exposure to ultraviolet radiation, or removal by a POTW or processor’s wastewater treatment method prior to its issuance into the environment.

• Environmental Effects of Released Substances.

Air
In its 2006 Chlorine Dioxide: Final Risk Assessment Case 4023, the EPA published the results of a toxicity study of chlorine dioxide in rats (including data on exposure through oral channels and inhalation).18 If the product is used and released to the environment as directed, exposure to SMT’s chlorine dioxide will be well below these thresholds:

The lowest inhalation endpoint provided in the study is the LC50 of 0.29 mg/L. Selective Micro Technologies’ chlorine dioxide is to be generated at 3 parts per million residual in-air. Chlorine dioxide at a 3 ppm residual is equal to: 

Selective Micro Technologies’ chlorine dioxide is to be generated at a residual of 3 ppm or  8.28 x 10-3 mg/L ClO₂ in-air. Because this concentration is significantly less than the inhalation toxicity endpoint of 0.29 mg/L provided in the EPA’s RED (Case 4023), Selective Micro Technologies maintains that air releases of the FCS will have a negligible impact.

Water.
In 2006, the EPA published their final decision on whether chlorine dioxide was eligible to be registered as a pesticide (the decision is captured in “Chlorine Dioxide: Final Risk Assessment Case 4023”).20 One of the analyses conducted to support the EPA decision on chlorine dioxide was the ecological hazard and risk assessment for chlorine dioxide. This ecological analysis explains that the ecological risk assessment relies on chlorite endpoints to be protective of chlorine dioxide and its degredates “because under environmental conditions, chlorine dioxide converts mostly into chlorite ions.” 21 While this Environmental Assessment has calculated EECs for chlorite, chlorate, and chloride, we follow the EPA’s approach and rely upon chlorite endpoints in our analysis. After use, Selective Micro Technologies’ chlorine dioxide will be diluted to a concentration of 0.25 ppm and released to the environment, where it will ultimately degrade to the chlorite ion (and the EEC for chloride is 0.013 ppm, lower than background levels, as discussed under Item 7b of this Environmental Assessment). Formations of the chlorite ion as a result of the disposal of a solution of Selective Micro Technologies’ chlorine dioxide will be well below chlorite ecological endpoints:

The lowest ecotoxicity endpoint provided in the study is the EC50 of 0.027 ppm. Because this concentration is greater than the EEC for chlorite provided in Section 6 of this EA (0.0175 ppm), Selective Micro Technologies maintains that the release of solutions of Selective Micro Technologies’ chlorine dioxide to the natural bodies of water will have a negligible impact.

Based upon these toxicity endpoints and the information provided in above sections, Selective Micro Technologies foresees no adverse effects on the environment as a result of the release of its chlorine dioxide to environmental channels.

Source: (Environmental Assessment for Food Contact Notification FCN 1764 http://www.fda.gov/Food/IngredientsPackagingLabeling/EnvironmentalDecisions/default.htm
An EA Revision Sheet has been prepared for this Environmental Assessment – See the FONSI for this Food Contact Notification )