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Acute Toxicity: inhalation

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acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
November 2003- April 2004
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study, performed according to standard method.

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guidelineopen allclose all
according to guideline
OECD Guideline 403 (Acute Inhalation Toxicity)
: One male rat was characterised by an excessive bodyweight (357g). This  was considered not to affect the purpose or integrity of the study.
according to guideline
EU Method B.2 (Acute Toxicity (Inhalation))
according to guideline
EPA OPPTS 870.1300 (Acute inhalation toxicity)
GLP compliance:
yes (incl. QA statement)
Test type:
standard acute method
Limit test:

Test material

Constituent 1
Chemical structure
Reference substance name:
Tetrakis(hydroxymethyl)phosphonium sulphate(2:1)
EC Number:
EC Name:
Tetrakis(hydroxymethyl)phosphonium sulphate(2:1)
Cas Number:
Molecular formula:
tetrakis(hydroxymethyl)phosphonium sulphate(2:1)
Test material form:
other: liquid stored at room temperature
Details on test material:
- Name of test material (as cited in study report):Tetrakishydroxymethylphosphonium Sulfate (THPS) 75% Aqueous Solution
- Physical state: a clear colourless and slightly viscous liquid (Provided by Cytec Industries Inc (USA)). Test substance not manufactured by Rhodia.
- Analytical purity: 75%
- Purity test date: no data
- Lot/batch No.: WE3090151
- Expiration date of the lot/batch: no data

Test animals

Details on test animals or test system and environmental conditions:
- Source: Charles River (UK) Ltd, Margate, Kent.
- Age at study initiation: eight to twelve weeks old.
- Weight at study initiation: 200g to 350g, except one male weighted 357g.
- Fasting period before study: no data
- Housing: groups of five by sex in solid-floor polypropylene cages.
- Diet (e.g. ad libitum): EU Rodent Diet 5LF2, BCM IPS Limited, London, UK.
- Water (e.g. ad libitum): ad libitum
- Acclimation period: five days

- Temperature (°C): 21 +/- 2°C
- Humidity (%): 55+/-15%
- Air changes (per hr): at least fifteen changes per hour.
- Photoperiod (hrs dark / hrs light): twelve hours continuous light and twelve hours darkness

Administration / exposure

Route of administration:
inhalation: aerosol
Type of inhalation exposure:
nose only
other: no vehicle
Details on inhalation exposure:
- Exposure apparatus: the animals were exposed to an atmosphere of the test item using a TSE Rodent Exposure System.
- Exposure chamber volume: 30 L
- Method of holding animals in test chamber: each rat was individually held in a tapered, polycarbonate restraining tube fitted onto a single tier of the exposure chamber. Only the nose of each animal was exposed to the test atmosphere.
- Method of conditioning air: no data
- System of generating particulates/aerosols: the test material was aerosolised using a glass concentric nebuliser located at the top of the exposure chamber. The nebuliser was connected to a glass syringe attached to an infusion pump, which provided a continuous supply of test material under pressure, and to a metered compressed air supply. Compressed air was supplied by means af an oil free compressor and passed through a water trap and respiratory quality filters before it was introduced to the nebuliser.
- Temperature, humidity, pressure in air chamber: the temperature and relative humidity inside the exposure chamber were measured by an electronic thermometer/humidity meter located in a vacant port in the animals'breathing zone of the chamber and recorded every thirty minutes throughout the four-hour exposure period. Oxygen levels within the exposure chamber were measured by an electronic oxygen analyser located in a sampling port in the animals breathing zone during each exposure period. The test atmosphere was generated to contain at least 19% oxygen.

- Samples taken from breathing zone: yes


TEST ATMOSPHERE (if not tabulated)
- Particle size distribution: the particle size of the generated atmosphere inside the exposure chamber was determined three times during each exposure period using a Marple Personal Cascade Impactor. This device consisted of six calibrated impactor stages with stainless steel collection substrates and a back up glass fibre filter, housed in an aluminium sampler. The mean amount for each stage was used to determine the cumulative amount below each cut-off point size. In this way, the proportion (%) of aerosol less than 9.9, 6.3, 3.6, 1.9, 0.89 and 0.24 µm was calculated.
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): MMAD was determined (as the 50% point) and the geometric standard deviation was calculated. In addition the proportion (%) of aerosol less than 4 µm (considered to be the inhalable portion) was determined.

CLASS METHOD (if applicable)
- Rationale for the selection of the starting concentration: a group of two rats (one male, one female) were exposed to an atmosphere of the test material at an approximate concentration of 0.5 mg/L for approximately fou hours. Slight respiratory effects were noted on both animals.
Analytical verification of test atmosphere concentrations:
Duration of exposure:
4 h
0.242; 0.525; 0.992 mg/L as active substance.
0.185, 0.394 and 0.744 mg/L as active ingredient.
No. of animals per sex per dose:
Control animals:
Details on study design:
- Duration of observation period following administration: fourteen or  twenty eight day observation period.
- Frequency of observations and weighing: all animals were observed for clinical signs at hourly intervals during exposure, immediately on removal from the restraining tubes at the end of exposure, one hour after termination of exposure and subsequently once daily for up to fourteen days (groups 1 and 2) or twenty-eight days (group 3). Any deaths or evidence of overt toxicity were recorded at each observation. Individual bodyweights were recorded prior to treatment on the day of exposure and Days 7, 14, and also Days 21 and 28 (group 3 only) or at death.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight and necropsy.
Finney and Trimmed Spearman-Karber Methods.

Results and discussion

Preliminary study:
Not applicable.
Effect levelsopen allclose all
Dose descriptor:
Effect level:
0.443 mg/L air
Based on:
act. ingr.
95% CL:
0.392 - 0.503
Exp. duration:
4 h
Dose descriptor:
Effect level:
0.591 mg/L air
Based on:
test mat.
95% CL:
0.523 - 0.67
Exp. duration:
4 h
No rats exposed to 0.242 mg/L (Group 2) died within the 14 days after  exposure. Four animals exposed to 0.525 mg/L (Group 3) were found dead or  were humanely killed within the prolonged observation period, from day 15  to 28 post-exposure. For the animals exposed to the highest concentration (Group 1 - 0.992 mg/L), on the 9 dead animals within the 14 days  post-exposure, 8 died during the first week, with 6 within the first day.
Clinical signs:
other: Common abnormalities noted during the study included  increased respiratory rate, noisy respiration, hunched posture,piloerection, red/brown staining to the eyes and/or snout and wet fur. In  addition, there were occasional instances of gasping respiratio
Body weight:
Bodyweight was monitored once a week. For Group 2 animals,  exposed at the lowest concentration (0.247 mg/L), bodyweight gain was considered as normal, both for males and females. For animals exposed to  the intermediary concentration (Group 3 - 0.525 mg/L) two males and four  females showed a bodyweight loss during week 1 of the study. These  animals recovered to show normal development at the end of week 2, except  for two females who died on day 15 post-exposure. For animals exposed at  the highest concentration (Group 1 - 0.992 mg/L) only 2 rats outlived by  one week (1 male and 1 female). Both animals loosed weight on this week  and died or did not recover during the following week.
Gross pathology:
Amongst animal that died during the study, macroscopic  abnormalities were detected on lungs with abnormal generalized or localized colours (red/dark), on liver with accentuated lobular pattern,  and kidneys whish appeared pale. Gastro-intestinal system (stomach, small  and large intestines) showed gaseous distension. Whatever the test concentration and the sex, the more frequent anatomic  abnormalities were found on lung.
Other findings:

Any other information on results incl. tables

Calculation of LC50 value:

The LC50 and their 95% confidence limits induced by a 4 hours exposure by the snout to the test substance are presented in the Table below, expressed as active substance (i.e. test substance) and as main ingredient (considering THPS concentration of 100%).

                                Active substance        main ingredient
LD50 combined             0.591                            0.443
(95% CI)                   (0.523-0.670)              (0.392-0.503)

LD50 males                    0.628                             0.471
(95% CI)                   (0.490-0.805)               (0.368-0.604)

LD50 females                 0.551                             0.413
(95% CI)                   (0.436-0.693)               (0.317-0.520)
95% CI: Confidence limits at 95%

Applicant's summary and conclusion

Interpretation of results:
Category 3 based on GHS criteria
Under the test conditions of this study, the acute inhalation median lethal concentrations (LC50) of THPS in all animals was 0.591 mg/L as active substance (THPS 75%) and 0.443 mg/L as main ingredient (THPS 100%).
Based on these results, THPS 75% was classified into Category 3 (H330) according to CLP Regulation (1272/2008).
Executive summary:

The acute inhalation toxicity of THPS 75% in water was assessed in a study according to the EPA OPPTS 870.1300 and OECD Guideline 403 and in accordance with GLP. In this study, groups of ten SD rats (five males and five females) were exposed to an aerosol atmosphere. The animals were exposed for four hours using a nose only exposure system, followed by a fourteen or twenty eight day observation period.


Based on results from a previous experiment (one male and one female exposed to the test substance concentration of 0.5 mg/L), 0.242; 0.525; 0.992 mg/L as active substance, corresponding to 0.185, 0.394 and 0.744 mg/L as active ingredient were tested.

Clinical signs were recorded during the exposure and daily during the subsequent 14 days (groups 1 and 2) and

28 days (group 3). The other recorded parameters were mortality, body weight and necropsy.


No rats exposed to 0.185 mg/L died within the 14 days after exposure. Four animals exposed to 0.394 mg/L were found dead or were humanely killed within the prolonged observation period, from day 15 to 28 post-exposure.

For the animals exposed to the highest concentration, on the 9 dead animals within the 14 days post-exposure,

8 died during the first week, with 6 within the first day.


Common clinical signs noted during the study included increased respiratory rate, noisy respiration, hunched posture, piloerection, red/brown staining to the eyes and/or snout and wet fur. In addition, there were occasional instances of gasping respiration and laboured respiration and isolated instances of decreased respiratory rate, hypothermia, los of righting reflex, dehydratation, sneezing, eye closed and damaged paw were also recorded.


Bodyweight was monitored once a week. For Group 2 animals, exposed at the lowest concentration (0.247 mg/

L), bodyweight gain was considered as normal, both for males and females. For animals exposed to the intermediary concentration (Group 3 - 0.525 mg/L) two males and four females showed a bodyweight loss during week 1 of the study. These animals recovered to show normal development at the end of week 2, except for two females who died on day 15 post-exposure. For animals exposed at the highest concentration (Group 1 - 0.992 mg/L) only 2 rats outlived by one week (1 male and 1 female). Both animals loosed weight on this week and died or did not recover during the following week.


Amongst animal that died during the study, macroscopic abnormalities were detected on lungs with abnormal generalized or localized colours (red/dark), on liver with accentuated lobular pattern, and kidneys whish appeared pale. Gastrointestinal system (stomach, small and large intestines) showed gaseous distension.

Whatever the test concentration and the sex, the more frequent anatomic abnormalities were found on lung.


Under the test conditions of this study, the acute inhalation median lethal concentrations (LC50) of THPS in all animals was 0.591 mg/L as active substance (THPS 75%) and 0.443 mg/L as main ingredient (THPS 100%).

Based on these results, THPS 75% was considered as Toxic if inhaled and classified into Category 3 (H331) according to the criteria of the CLP Regulation (EC) N° 1272/2008.

This acute inhalation study is classified as acceptable. It satisfies the guideline requirement for an acute inhalation study in the rats.