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Six-month low level chlorine dioxide gas inhalation toxicity study with two-week recovery period in rats.

Akamatsu A, Lee C, Morino H, Miura T, Ogata N, Shibata T - J Occup Med Toxicol (2012)

Bottom Line: No significant difference was observed in body weight gain, food and water consumptions, and relative organ weight.In biochemistry and hematology examinations, changes did not appear to be related to CD gas toxicity.In necropsy and histopathology, no CD gas-related toxicity was observed even in expected target respiratory organs.

View Article: PubMed Central - HTML - PubMed

Affiliation: Taiko Pharmaceutical Co,, Ltd, Suita-shi, Osaka, Japan. akinori.akamatsu@seirogan.co.jp.

ABSTRACT

Background: Chlorine dioxide (CD) gas has a potent antimicrobial activity at extremely low concentration and may serve as a new tool for infection control occupationally as well as publicly. However, it remains unknown whether the chronic exposure of CD gas concentration effective against microbes is safe. Therefore, long-term, low concentration CD gas inhalation toxicity was studied in rats as a six-month continuous whole-body exposure followed by a two-week recovery period, so as to prove that the CD gas exposed up to 0.1 ppm (volume ratio) is judged as safe on the basis of a battery of toxicological examinations.

Methods: CD gas at 0.05 ppm or 0.1 ppm for 24 hours/day and 7 days/week was exposed to rats for 6 months under an unrestrained condition with free access to chow and water in a chamber so as to simulate the ordinary lifestyle in human. The control animals were exposed to air only. During the study period, the body weight as well as the food and water consumptions were recorded. After the 6-month exposure and the 2-week recovery period, animals were sacrificed and a battery of toxicological examinations, including biochemistry, hematology, necropsy, organ weights and histopathology, were performed.

Results: Well regulated levels of CD gas were exposed throughout the chamber over the entire study period. No CD gas-related toxicity sign was observed during the whole study period. No significant difference was observed in body weight gain, food and water consumptions, and relative organ weight. In biochemistry and hematology examinations, changes did not appear to be related to CD gas toxicity. In necropsy and histopathology, no CD gas-related toxicity was observed even in expected target respiratory organs.

Conclusions: CD gas up to 0.1 ppm, exceeding the level effective against microbes, exposed to whole body in rats continuously for six months was not toxic, under a condition simulating the conventional lifestyle in human.

No MeSH data available.


Related in: MedlinePlus

A schematic diagram of the set-up of a CD gas exposure chamber. CD gas discharged from the CD gas generator shown at the left was mixed with air by an airfoil fan, then sent to a mixing chamber and flown through a perforated, flow lamination plate to yield an even, regulated concentration CD gas flow throughout cages housing animals in the exposure chamber. A probe of CD gas detector was placed in the middle of the chamber to monitor the CD gas concentration continuously. The ventilation rate in the chamber was 30 times per hour. In order to ensure the even exposure of CD gat to rats, the position of cages were rotated once weekly. In an experiment prior to the study, it was confirmed that the existence of animals, chow, water, and excrements did not affect the flowing CD concentration (data not shown). It was also confirmed that the CD gas concentration was equal at the inlet and at the outlet as well as at the center of the chamber (data not shown).
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Figure 1: A schematic diagram of the set-up of a CD gas exposure chamber. CD gas discharged from the CD gas generator shown at the left was mixed with air by an airfoil fan, then sent to a mixing chamber and flown through a perforated, flow lamination plate to yield an even, regulated concentration CD gas flow throughout cages housing animals in the exposure chamber. A probe of CD gas detector was placed in the middle of the chamber to monitor the CD gas concentration continuously. The ventilation rate in the chamber was 30 times per hour. In order to ensure the even exposure of CD gat to rats, the position of cages were rotated once weekly. In an experiment prior to the study, it was confirmed that the existence of animals, chow, water, and excrements did not affect the flowing CD concentration (data not shown). It was also confirmed that the CD gas concentration was equal at the inlet and at the outlet as well as at the center of the chamber (data not shown).

Mentions: CD gas was obtained from an electrochemical system [21]. Briefly, CD gas was generated by dissolving the electrolytically-evolved product of potassium chloride into sodium chlorite solution. The experimental set-up for the exposure of CD gas to rats is shown in Figure 1. Hermetic inhalation exposure chambers, each size of which was 700 W × 1350D × 1600H mm, were made up with stainless steel and transparent vinyl chloride plates. The ventilation rate in the chamber was 30 times per hour. To maintain even CD gas flow and homogenous CD gas concentration in the chamber, five small-size (25 mm × 25 mm × 10 mm) direct current electric fans with an airflow rate of 0.048 m3/min (F2510CT-12UCV, Shicoh Engineering, Kanagawa, Japan) were placed in each chamber. The rats of the same gender were housed as two animals per stainless steel wire mesh cage in the chamber. The CD gas concentration in the chamber was regulated by adjusting the electric current of the electrolysis, and was monitored continuously by a CD gas detector (CS-7 with a CDS-7 sensor, New Cosmos Electric, Osaka, Japan). The CD gas monitoring device was calibrated once daily against a CD gas glass tube detector (No. 23 M, Gastec, Kanagawa, Japan).


Six-month low level chlorine dioxide gas inhalation toxicity study with two-week recovery period in rats.

Akamatsu A, Lee C, Morino H, Miura T, Ogata N, Shibata T - J Occup Med Toxicol (2012)

A schematic diagram of the set-up of a CD gas exposure chamber. CD gas discharged from the CD gas generator shown at the left was mixed with air by an airfoil fan, then sent to a mixing chamber and flown through a perforated, flow lamination plate to yield an even, regulated concentration CD gas flow throughout cages housing animals in the exposure chamber. A probe of CD gas detector was placed in the middle of the chamber to monitor the CD gas concentration continuously. The ventilation rate in the chamber was 30 times per hour. In order to ensure the even exposure of CD gat to rats, the position of cages were rotated once weekly. In an experiment prior to the study, it was confirmed that the existence of animals, chow, water, and excrements did not affect the flowing CD concentration (data not shown). It was also confirmed that the CD gas concentration was equal at the inlet and at the outlet as well as at the center of the chamber (data not shown).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3298712&req=5

Figure 1: A schematic diagram of the set-up of a CD gas exposure chamber. CD gas discharged from the CD gas generator shown at the left was mixed with air by an airfoil fan, then sent to a mixing chamber and flown through a perforated, flow lamination plate to yield an even, regulated concentration CD gas flow throughout cages housing animals in the exposure chamber. A probe of CD gas detector was placed in the middle of the chamber to monitor the CD gas concentration continuously. The ventilation rate in the chamber was 30 times per hour. In order to ensure the even exposure of CD gat to rats, the position of cages were rotated once weekly. In an experiment prior to the study, it was confirmed that the existence of animals, chow, water, and excrements did not affect the flowing CD concentration (data not shown). It was also confirmed that the CD gas concentration was equal at the inlet and at the outlet as well as at the center of the chamber (data not shown).
Mentions: CD gas was obtained from an electrochemical system [21]. Briefly, CD gas was generated by dissolving the electrolytically-evolved product of potassium chloride into sodium chlorite solution. The experimental set-up for the exposure of CD gas to rats is shown in Figure 1. Hermetic inhalation exposure chambers, each size of which was 700 W × 1350D × 1600H mm, were made up with stainless steel and transparent vinyl chloride plates. The ventilation rate in the chamber was 30 times per hour. To maintain even CD gas flow and homogenous CD gas concentration in the chamber, five small-size (25 mm × 25 mm × 10 mm) direct current electric fans with an airflow rate of 0.048 m3/min (F2510CT-12UCV, Shicoh Engineering, Kanagawa, Japan) were placed in each chamber. The rats of the same gender were housed as two animals per stainless steel wire mesh cage in the chamber. The CD gas concentration in the chamber was regulated by adjusting the electric current of the electrolysis, and was monitored continuously by a CD gas detector (CS-7 with a CDS-7 sensor, New Cosmos Electric, Osaka, Japan). The CD gas monitoring device was calibrated once daily against a CD gas glass tube detector (No. 23 M, Gastec, Kanagawa, Japan).

Bottom Line: No significant difference was observed in body weight gain, food and water consumptions, and relative organ weight.In biochemistry and hematology examinations, changes did not appear to be related to CD gas toxicity.In necropsy and histopathology, no CD gas-related toxicity was observed even in expected target respiratory organs.

View Article: PubMed Central - HTML - PubMed

Affiliation: Taiko Pharmaceutical Co,, Ltd, Suita-shi, Osaka, Japan. akinori.akamatsu@seirogan.co.jp.

ABSTRACT

Background: Chlorine dioxide (CD) gas has a potent antimicrobial activity at extremely low concentration and may serve as a new tool for infection control occupationally as well as publicly. However, it remains unknown whether the chronic exposure of CD gas concentration effective against microbes is safe. Therefore, long-term, low concentration CD gas inhalation toxicity was studied in rats as a six-month continuous whole-body exposure followed by a two-week recovery period, so as to prove that the CD gas exposed up to 0.1 ppm (volume ratio) is judged as safe on the basis of a battery of toxicological examinations.

Methods: CD gas at 0.05 ppm or 0.1 ppm for 24 hours/day and 7 days/week was exposed to rats for 6 months under an unrestrained condition with free access to chow and water in a chamber so as to simulate the ordinary lifestyle in human. The control animals were exposed to air only. During the study period, the body weight as well as the food and water consumptions were recorded. After the 6-month exposure and the 2-week recovery period, animals were sacrificed and a battery of toxicological examinations, including biochemistry, hematology, necropsy, organ weights and histopathology, were performed.

Results: Well regulated levels of CD gas were exposed throughout the chamber over the entire study period. No CD gas-related toxicity sign was observed during the whole study period. No significant difference was observed in body weight gain, food and water consumptions, and relative organ weight. In biochemistry and hematology examinations, changes did not appear to be related to CD gas toxicity. In necropsy and histopathology, no CD gas-related toxicity was observed even in expected target respiratory organs.

Conclusions: CD gas up to 0.1 ppm, exceeding the level effective against microbes, exposed to whole body in rats continuously for six months was not toxic, under a condition simulating the conventional lifestyle in human.

No MeSH data available.


Related in: MedlinePlus