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Toxicity to other above-ground organisms

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Endpoint:
toxicity to other above-ground organisms
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
Marine toads (B. marinus) were exposed to 0.8 ppm ozone for 4 hours. Subsequently the effects on feeding and locomotor behaviour were evaluated.
GLP compliance:
no
Analytical monitoring:
yes
Details on sampling:
continuous monitoring
Vehicle:
no
Details on preparation and application of test substrate:
The exposure system used in this study has been described in Dohm et al (2001). The system was designed to deliver either air filtered to remove particles or O3 diluted with filtered air to four exposure chambers (two air, two O3). A parallel exposure system (excluding the O3 generators) was used to deliver air to one or two air-only exposure chambers. Exposure atmospheres were generated by mixing O3 with air drawn from outside the laboratory building at 5 L/min.
The air–O3 mix was then drawn from the flask and diverted to a steel manifold and up to four exposure chambers (975-ml glass jars). Flow rates through the exposure chambers were controlled by upstream steel needle valves calibrated with a mass flow meter to deliver 250 ml/min.
Test organisms (species):
other: Bufo marinus
Details on test organisms:
65 adult male and female B. marinus were collected from lawns in Hilo (HI, USA) for use in this study. Forty toads were used in the feeding trials (body mass mean 92 +/- 28.0 g, range 48–164 g); 25 toads were used for the open field arena trials (body mass 97 +/- 19.7 g, range 60–138 g). Toads were housed individually in plastic cages (15 x 20 x 26 cm) with access to a small shelter and water in temperature-controlled (22–25 degrees centigrade) housing with a 13:11 h light:dark photocycle. No basking light was provided, nor was food provided, which was intended to standardize postabsorptive state. Ozone levels on windward coastal Hawaiian Islands represent atmospheric background levels only; therefore, these toads had not been previously exposed to appreciable amounts of ozone.
Study type:
laboratory study
Limit test:
no
Total exposure duration:
4 h
Post exposure observation period:
1, 24 and 48 h.
Test temperature:
Feeding trials: 22 – 25 degrees centigrade
Humidity:
Relative humidity: 50 – 65%.
Photoperiod and lighting:
13:11 h light:dark photocycle
Details on test conditions:
Feeding trials
One to two days after capture, toads were offered five mealworms (Tenebrio molitor) to assess their willingness to consume mealworms (i.e., pre-exposure trial). After 24 h, the total number of mealworms eaten by each toad was recorded. Only toads that ate one or more mealworms during the pre-exposure trial were used for subsequent observations; these toads were randomly assigned to exposure groups. Two days after the pre-exposure test, toads were placed individually into glass jars and connected to the exposure system to receive air or ozone for 4 h. After the exposure was completed, toads were weighed and core body temperature (Tb) was recorded via a thermocouple probe inserted into the cloaca. Toads were placed back into clean standard cages, and five mealworms were introduced to each cage. The number of mealworms eaten were counted 1 h after exposure. Uneaten mealworms were removed if present. A new batch of five mealworms was added, and at 24 h post-exposure, the number of mealworms eaten was scored again, and remaining mealworms were removed and replaced with five new mealworms. At 48 h post-exposure, the number of mealworms eaten was counted again.

Open-field trials
Movement of individual toads (n_25) within an open arena was recorded for 1 h on three consecutive days: once before exposure, again 1 h post-exposure, then a third time 24 h after exposure. A circular, open arena (area 2.9 m2) was constructed from landscape edging on a floor of short-piled artificial turf. The flooring was marked into grids of 25 by 25 cm. The arena was covered with a thin, clear vinyl covering, and only dim lighting was used for illumination of the arena (60-W broad-spectrum bulb, 10 m away from the arena). Toads were placed individually into the arena and covered with a small cardboard box for 5 min before the start of a trial. Two potential covariates were recorded after a trial for each toad as potential. Core body temperature was measured with a thermocouple probe inserted 2 cm into the cloaca. For repeat measures, toads were tested at approximately the same time on subsequent trials; therefore, the rank order was preserved across trial days. Thus, this protocol induced a correlation between body temperature and time of day at start of the trial. However, because the assignment of toads to exposure groups was random with respect to time of day, there was no statistical difference for body temperature between the exposure groups (no exposure, air, O3: analysis of variance [ANOVA]). A video camera was interfaced to a VCR and monitor so that trials could be viewed without disturbing the toads. Taped recordings of each trial were then analysed for total distance moved (counted as number of squares crossed), total time spent moving (moving), and percent time spent by the toad along the edge versus in the middle of the arena (edge). The number of squares crossed, as opposed to a direct tracing of path covered by each toad, was counted.
Nominal and measured concentrations:
A concentration of 0.6 µl/L (= 0.6 ppm) O3 was used for all exposures, which corresponds to levels at the upper range of historical observations in urban settings
Reference substance (positive control):
no
Details on results:
Feeding trials (see table 1):
Nineteen of 40 toads did not eat mealworms during the 24-h prefeeding trial and were therefore excluded from this study. Mean body mass was not statistically different between toads that ate (95 +/- 29 g) or did not eat (86 +/- 26.5 g, two sample t = 0.87, df= 38, p= 0.390). The remaining 21 toads ate an average of 3.7 (+/- 1.53) mealworms during the prefeeding trial. After exposure (1, 24, and 48 h), all toads ate at least one mealworm. Postexposure (1 and 48 h), air-exposed toads ate significantly more of the mealworms offered than did O3-exposed toads. The trend was in the same direction for the 24-h postexposure trial, but the difference was not statistically significant. For the subset of toads from both groups that ate three or more mealworms at the prefeeding trial, O3-exposed toads consumed fewer mealworms offered compared with air-exposed toads at 1 h (airexposed toads 77.5%, O3-exposed toads 30%; p = 0.0003), 24 h (92.5% air, 80% O3; p =0.0725), and 48 h (100 % air, 76.6% O3; p = 0.0053). The pattern also held for the subset of toads that ate four or five mealworms at the prefeeding trial: air exposed toads consumed more mealworms offered 1 h (80% air, 36% O3; p =0.0006), 24 h (97.1% air, 80% O3; p = 0.0372), and 48 h (100% air, 66.6% O3; p =0.0045) postexposure.
To account for individual differences, a Friedman’s test was used, with individual toad as a blocking effect, and trial (pre-, and the three postexposure trials) as main effects. Analyses were conducted separately for air- and O3-exposed toads. Compared with the pre-feeding trial, no differences were found for numbers of mealworms eaten by each toad for any of the postexposure trials for the air-exposed toads (grand median = 5.0; Friedman S = 4.79, df = 3, p =0.188, adjusted for ties). Toads exposed to O3, however, ate fewer mealworms compared with their prefeeding records (grand median =3.1, Friedman S = 10.78, df = 3, p = 0.013, adjusted for ties), particularly for the 1-h postexposure trial.
Results with reference substance (positive control):
n/a
Reported statistics and error estimates:
See details on results

Table 1. Fisher exact tests (one-tailed) for comparisons of mealworms (Tenebrio molitor) eaten by toads (Bufo marinus) during 24-h trials beginning 1, 24, and 48 h after a single 4-h exposure to air or to an air–ozone (O3) mix (0.6 l/L) at a flow rate of 250 ml/min (*).

 

No. of toads that ate at

least one mealworm

Mealworms eaten by toads

 

Yes

No

p

No.

eaten

No. not

eaten

p

1 h after exposure

Air

8

4

0.1179

36

24

0.0005

O3

3

6

 

12

33

 

24 h after exposure

Air

10

2

0.4466

47

13

0.1526

O3

8

1

 

33

12

 

48 h after exposure

Air

9

1

0.3088

41

9

0.0001

O3

5

2

 

23

27

 

* Toads were screened before exposure for willingness to eat mealworms. At each trial, toads were offered five mealworms (total mass of mealworms between 0.5 and 1.0 g), and scoring of mealworms eaten was conducted 24 h later.

Validity criteria fulfilled:
not applicable
Remarks:
not to guideline
Conclusions:
The results suggest that a single 4-h exposure to ozone depresses toad feeding behavior after exposure but had little effect on voluntary locomotor behavior.
Executive summary:

Ozone, a reactive component of air pollution, depresses feeding and voluntary locomotor behavior in laboratory rodents, but the effects of ozone on amphibian behavior are not known. The effects of 4 h of exposure to air or ozone (0.6 ppm), on two ecologically relevant behaviors of the toad Bufo marinus were evaluated. Toads were offered five mealworms at 1, 24, and 48 h after exposure. One hour after exposure, ozone -exposed toads ate fewer mealworms than did air-exposed toads. Within 24 h after exposure, all toads ate four or five mealworms. Movement is a key component of toad feeding behavior. Additional toads were tested (n = 25) for voluntary locomotor behavior during three 1-h trials in a 2.9-square meter open-field arena. Mean total distance moved was: pre-exposure, 29 ± 19.5 m; 1-h postexposure, 13 ± 15.6 m; and 24-h postexposure, 17 ± 17.4 m. The means were not statistically different by repeated measures analysis of covariance. The authors concluded that O3 affects many aspects of toad behavior and physiology in a manner consistent with the extensive literature on humans and other mammals.

Endpoint:
toxicity to other above-ground organisms
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
Marine toads (B. marinus) were exposed to 0.8 ppm ozone in air for 4 hours. Subsequently the effects on evaporative water loss and thermoregulatory behaviour were evaluated.
GLP compliance:
no
Analytical monitoring:
yes
Details on sampling:
Continuous monitoring
Vehicle:
no
Details on preparation and application of test substrate:
Exposure system: Toads were exposed once to either air or O3. The exposure system was designed to deliver either filtered air or O3 diluted with filtered air to two metabolic chambers, one containing the toad and the other serving as a baseline for metabolic measurements (data not reported). A concentration of 0.8 ppm O3 was used for all exposures. This O3 concentration corresponds to O3 levels at the upper range of observations in urban settings and is a level that induces significant, but transient respiratory irritation in mammals in short-term single exposures lasting several hours.

Exposure atmospheres were generated by the mixing of O3 with air drawn from outside the laboratory building at 5 L/min through a rotameter with a pump. The O3 generators were connected in series and output from the generators was diverted to a 1-L Erlenmeyer flask resting on a magnetic stirring plate set at low stir rate. The air/O3 mix was then drawn from the Erlenmeyer flask and diverted to the exposure chambers (450-ml glass jars). Flow rates through the exposure chambers were controlled by downstream flow meters set to deliver about 250 mL/min corrected to standard temperature and pressure (STP). The temperature cabinet and exposure chambers were contained in a Plexiglas box (0.456 m3) and exposure air streams were vented to the outside via an exhaust fan. The exposure system was constructed with fluorocarbon, glass, or stainless steel components to minimize the reactive absorbance from generation to delivery at the exposure chamber. In addition, the system initially was flushed with > 0.8 ppm O3 for 30 min to saturate any reactive surfaces prior to the start of an exposure trial. Barometric pressure and flow meter temperature were recorded at the start and end of an exposure trial and the data were used to correct flow rates to STP conditions. All flow rates through rotameters were set by calibration to flow rates through glass bubble-flow meters.
Test organisms (species):
other: Marine toad (Bufo marinus)
Details on test organisms:
A total of 66 male and female marine toads (B. marinus, body mass 90.1 +/- 21.9 g, min 49.9 g, max 150.2 g) were used for the experiment. Thirty-two were randomly assigned to the ozone-exposed groups and 34 were assigned to the control (clean air) group. A subset of 22 toads (body mass 89.5 +/- 18.94 g) was used to measure thermal preferences after exposure to air (N=11) or ozone (N=11). Toads were collected by hand, after sunset, from grass lawns in Hilo, Hawaii. Toads were housed individually in plastic cages (15 x 20 x 26 cm) with access to a small shelter and tap water (the water was taken from a source that had sat at least 24 h so that chlorinated compounds could dissipate). Toads were acclimated to laboratory conditions for an average of 7 days (range 1 - 27 days) before exposure or thermal gradient trials were initiated. Food was generally not provided to standardize feeding status as postabsorptive. When food (crickets) was provided, a minimum of 7 days was allowed to pass before the toad was measured. All toads appeared to remain healthy during the short captivity period.
Study type:
laboratory study
Limit test:
no
Total exposure duration:
4 h
Post exposure observation period:
1, 24 and 48h
Test temperature:
For the first 5 months of the experiment relative humidity and room temperature were not controlled in the animal room and both tracked ambient conditions. Room temperature ranged from a nighttime low of 16 degrees centigrade (mean 20.2 +/- 1.70) to a daytime high of 28 degrees centigrade (mean 26.3+/- 1.60 degrees centigrade). For the remaining 4 months of the study toads were housed under controlled temperature (22 degrees centigrade) conditions.
Humidity:
For the first 5 months of the experiment relative humidity and room temperature were not controlled in the animal room and both tracked ambient conditions. Room RH ranged from 70 to 90% (83.8 +/- 5.34%). For the remaining 4 months of the study toads were housed under controlled RH (60%) conditions.
Photoperiod and lighting:
The room was on a 13:11 light:dark cycle, but some ambient light also reached the toads.
Details on test conditions:
Thermal gradient and recording of thermoregulatory behavior.
Each PBT (preferred body temperature) toad was measured on a fully saturated thermal gradient on 5 consecutive days for a total of 4.5 h per day. Two PBT trials preceded the exposure with three trials after exposure (1 h post-, 24 h post-, and 48 h post-exposure). Toads moved freely along the length of the gradient that ranged from 4 to 40 degrees centigrade. All PBT trials of exposed toads were initiated at 12 PM and completed by 5 PM HST. Body temperatures from toads were recorded as they moved freely within the gradient under full water vapor saturation. At the end of a trial, toads were returned to their standard cages and placed directly into bowls containing water to facilitate rehydration.
Before a toad was placed in the thermal gradient, the body mass of the toad was measured and recorded as the starting body mass. Next, the initial body temperature was recorded. The toad was then placed in the middle of the gradient with the head oriented toward the warm end. With the ceiling in place, the top of the gradient was covered with a black plastic sheet. One hour after placing the toad into the gradient, the toad’s body temperature was recorded once per half-hour, with a minimum of 25 min between readings. After each reading, the toad was returned to the same general location at about the middle of the gradient with the head pointing toward the warm end. At the end of each trial, the final body mass and final body temperature were recorded. Three measures of TB were derived for each thermal gradient trial: (1) preferred body temperature (PBT) is the calculated mean TB from all of the 12 –h recordings, (2) voluntary minimum (Vmin) is the lowest TB voluntarily selected (i.e., observed in the gradient) by a toad, and (3) voluntary maximum (Vmax) is the highest TB voluntarily selected (i.e., observed in the gradient) by a toad. Two measures of thermoregulatory precision were determined: (1) the variance around PBT and (2) the slope of the regression of the eight TB recordings and the eight ambient temperature data points corresponding to the location along the gradient at which the toad was found. Linear regression was used to obtain the slope of this relationship and the mean slopes for the 11 ozone-exposed toads were compared to the mean slopes for the 11 air-exposed toads.
Nominal and measured concentrations:
0.8 ppm (measured)
Reference substance (positive control):
no
Details on results:
- 4h exposure to ca. 0.8 ppm ozone lead to evaporative water loss
- One hour after ozone exposure: the prior day’s performance explained significant amounts of variation in PBT and Vmin, but not Vmax, for control toads. Body mass and EWL accounted for significant variation in Vmin, but not for PBT or for Vmax. - For the O3-exposed toads 1 h after exposure, only the prior day’s performance significantly covaried with thermoregulatory behavior (Vmax, Vmin, but not PBT).

- Twenty-four hours after ozone exposure, EWL had a negative effect on all measures of thermoregulatory behavior in ozone-exposed toads. Compared to controls, O3-exposed toads selected lower Vmin, Vmax, and PBT. The day’s prior performance was a significant predictor for all measures of thermoregulatory behavior except for Vmax.

- Forty-eight hours after ozone exposure, only the prior day’s thermoregulatory behavior predicted any significant variation in PBT. No predictors were statistically significant for Vmax or Vmin.
Validity criteria fulfilled:
not applicable
Remarks:
not to guideline
Conclusions:
Ozone exposure may alter water balance and indirectly thermal preferences in anuran amphibians.
Executive summary:

Compared to individuals exposed to air, Bufo marinus toads exposed to ozone for 4 h lost 3.78 g body mass (adjusted mean from analysis of covariance, body mass mean 90.1 +/- 21.90 g). The thermoregulatory responses of toads in a thermal gradient were tested 1, 24, and 48 h after 4-h exposure to air or 0.8 ppm ozone. Individual toad thermal preferences were also significantly repeatable across all trials. No direct effect of ozone exposure on the preferred body temperatures (PBT) of toads was observed. However, ozone exposure did have an indirect effect on selected temperatures. Ozone-exposed toads with higher evaporative water loss rates, in turn, also selected lower PBT, voluntary minimum, and voluntary maximum temperatures 24 h post-exposure. Ozone exposure may thus alter both water balance and thermal preferences in anuran amphibians.

Endpoint:
toxicity to other above-ground organisms
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
1. Poikilothermic lizards (Sceloporus occidentalis) were exposed to O3 and then the body temperatures measured.
2. Breathing patterns and respiratory gas exchange of P. cadaverina frogs were measured during the course of experimental O3 exposure.
GLP compliance:
no
Analytical monitoring:
yes
Details on sampling:
continuously
Vehicle:
no
Details on preparation and application of test substrate:
Ozone exposures of lizards were performed in 1 m3 stainless steel Rochester inhalation exposure chambers. Air supplying the chambers was initially passed through coarse particle filters and gas scrubbers, humidified to 60 % relative humidity, and then passed through high efficiency particle filters. The generated O3 was diluted into purified air passing to the chamber to produce the target concentration. Changes in O2 content of the air due to addition of O3 and medical-grade O2 were less than 0.02 %.

Lizards were exposed in stainless steel wire mesh cages inside the Rochester chambers, to mean ± S.D. 0.60 ± 0.04 ppm O3 at 25.1 ± 0.7 °C and 49 ± 2 % relative humidity or 34.8 ± 3.3 °C and 33 ± 3 % relative humidity.
Frogs were exposed in glass jars containing a small amount of liquid water and capped with rubber stoppers lined with fluorocarbon tape. Because O3 is highly reactive, it is important to use oxidation-resistant materials like stainless steel, glass, or fluorocarbon plastics in exposure systems to avoid scrubbing losses of O3. Purified air or air containing O3 was drawn through fluorocarbon tubing and through the glass chambers. Frogs were exposed at 21.0 ± 0.2 °C, and at a relative humidity (inlet air stream) of 85 ± 2 % to O3 concentrations of 0.21 ± 0.01, 0.40 ± 0.01, or 0.83 ± 0.02 ppm.
Test organisms (species):
other: Lizard (Sceloporus occidentalis) and frog (Pseudacris cadaverina).
Details on test organisms:
Lizards and frogs were collected from the field in southern California and maintained in purified air laboratory housing for 2 weeks before testing. Potential field acclimatization of study subjects to local levels of oxidant air pollution was minimized temporally by collecting animals in early spring season and geographically by selecting collecting sites with relatively low exposure from upwind urban sources. Lizards were collected near the coast at the University of California, Irvine. Frogs were captured at San Mateo Creek in the southern Santa Ana Mountains. Lizards were maintained in cages offering incandescent light for photoperiod and thermoregulation, shelter, gravel bedding, and ad lib. food (crickets and Tenebrio larvae) and drinking water. Frogs were maintained in plastic cages at 22°C with paper towel bedding, a water bowl, and ad lib. crickets for food. All food was removed 2 days prior to exposure experiments in order to place the animals in post-absorptive physiological status.
Study type:
laboratory study
Limit test:
no
Total exposure duration:
4 h
Post exposure observation period:
Lizards: 2 days
Test temperature:
Lizards: 25.1 +/- 0.7 and 34.8 +/- 3.3 °C
Frogs: 21.0 +/- 0.2 °C
Humidity:
Lizards: 49.2 +/- 0.7% RH at 25.1 °C and 33.3 +/- 3.3% RH at 34.8.°C
Frogs: 85 +/- 2% RH
Photoperiod and lighting:
Tests were performed under artificial lighting.
Details on test conditions:
Ozone exposures of lizards were performed in 1 cubic meter stainless steel Rochester inhalation exposure chambers. Frogs were exposed in glass jars containing a small amount of liquid water.
Nominal and measured concentrations:
Measured concentrations:
Lizards: 0 and 0.60 +/- 0.04 ppm.
Frogs: 0, 0.21 +/- 0.01, 0.40 +/- 0.01, or 0.83 +/- 0.02 ppm.
Reference substance (positive control):
no
Details on results:
1. Lizards (Fig 1)
Purified air control lizards selected similar body temperatures (mean 35.3 °C ) on each of the 3 days (Fig. 1A). A separate group of lizards exposed at 25°C to 0.6 ppm O3 selected body temperatures 1.6 °C lower than on day 1, but on the day after exposure, their selected body temperatures had recovered to purified air control levels.
This behavioral hypothermic response was much stronger following exposure to 0.6 ppm O3 performed at an elevated but more realistic 35 °C activity body temperature for S. occidentalis (Fig. 1C). Body temperature was depressed by 1.9 °C immediately following exposure, and when tested the day after exposure, lizard body temperature was further depressed to 31.7 °C, amounting to 3.3 °C of behavioral hypothermia. Two way repeated measures analysis of variance of body temperature was significant for the main effect of day in the 25 °C O3 exposure series (Fig. 1B: F2,10 = 7.8, p < 0.01) and 35 °C exposure series (Fig. 1C: F2,8 = 9.2, p < 0.01). There were no significant effects of individual lizard in any of the series or of any variable in the control purified air series (Fig. 1A). On the occasion of transferring lizards from the O3 exposure chamber to the temperature gradient there was no obvious effect of O3 exposure on the appearance of the animals with respect to their alertness or capacity for locomotion in the gradient.
2. Frogs (Fig 2)
Fig. 2 shows the changes in breathing pattern and gas exchange of the frogs between the first and last hour of the exposure. At the beginning of the exposure, purified air control frogs occasionally changed position in the chambers but then settled down to a stationary but alert posture typical of P. cadaverina perched on stones by streams. Frogs in O3 also became stationary with the exception of one individual in 0.8 ppm O3, which frequently moved to reposition itself throughout the 4-h exposure. This individual is distinguished in Fig. 2 from measures of all other stationary frogs. Buccal pumping rate declined in all exposure groups including purified air, and there was no statistically significant influence of O3 on this change. Lung ventilation, however, was drastically affected by O3. In 0.8 ppm O3, flank movements ceased in all animals that remained in position. The single active frog in 0.8 ppm O3 maintained observable lung ventilation as it repositioned itself about the chamber. While frogs in 0.4 ppm O3 used lung ventilation during the first hour of exposure, all abdominal flank movements had ceased by the fourth hour.
Lung gas exchange may not have been entirely eliminated in frogs that stopped flank movements, but any lung volume change in this circumstance was so slow as to be unobservable to the eye. Oxygen consumption declined in frogs exposed to O3 except for the single individual that remained active in 0.8 ppm O3 (hour 4 oxygen consumption of stationary frogs in purified air vs. O3 F1,13=6.1, pb0.03).
There was no statistically significant effect of different O3 concentrations among these hour 4 oxygen consumption data, but the high level of arousal and movement of the exceptional individual in 0.8 ppm O3 suggests that a dose–response relation for oxygen consumption may not be a monotonic function over this range of O3 concentrations.
As the exposures progressed, frogs at rest and exposed to 0.4 and 0.8 ppm O3 adopted a low profile with the head down, eyes moderately retracted although not shut, and limbs gathered tight against the body. A similar posture is observed in terrestrial frogs under mild dehydration stress and termed the “water conservation posture” as it minimizes the surface area exposed for evaporation. In the present experiments, the frogs were either sitting in a thin layer of liquid water in the chambers or clinging to the walls adjacent to liquid water, and they were not subjected to dehydration stress. In this case, adoption of this posture served to minimize exposure of the skin surface to the O3. By curtailing lung ventilation, the pulmonary epithelium too was defended against O3 exposure.
Reported statistics and error estimates:
See details on results
Validity criteria fulfilled:
not applicable
Remarks:
not to guideline
Conclusions:
The species tested in this study responded to ozone exposure by reducing exposure. A transient effect on body temperature was observed in the lizards when exposed for 4h to 0.6 ppm at 25 °C, while the animals had not recovered when exposed under to same conditions at 35.3 °C. In frogs the NOEC was 0.2 ppm for the respiratory parameters studied.
Executive summary:

Ozone at concentrations found in urban air pollution is known to have significant physiological effects on humans and other mammals. Exposure of the lizard, Sceloporus occidentalis, to 0.6 ppm ozone for 4 h at 25 °C induced 1.6 °C of behavioral hypothermia immediately following exposure, but selected body temperature recovered the next day. Lizards exposed at 35 °C to 0.6 ppm ozone for 4 h selected induced body temperatures 1.9 °C below controls after exposure, and the behavioral hypothermic response persisted and increased to 3.3 °C the following day. Four-hour exposures of the frog, Pseudacris cadaverina, to 0.2 to 0.8 ppm ozone resulted in concentration-dependent alterations of respiration including depression of lung ventilation and oxygen consumption and the adoption of a low profile posture that reduced the exposed body surface.

Description of key information

Studies in frog, toad and lizard show that changes in behaviour were observed at ozone concentrations between 0.2 and 0.8 ppm in air. However, during normal use of ozone in the envisaged disinfectant applications, no additional exposure of these animals to ozone from biocidal use is expected.

Key value for chemical safety assessment

Additional information