Dichromium nitride

Endpoint summary

Description of key information

Acute oral toxicity

No acute oral toxicity studies with dichromium nitride are available, thus the acute toxicity will be addressed with existing data on chromium picolinate monohydrate using a category read-across concept.

 

Chromium picolinate monohydrate was administered in F344/N rats and B6C3F1 mice for 14 weeks in doses of up to 4240 mg/kg bw/day and 11900 mg/kg bw/day, respectively. This corresponds to a dose of 530 and 1488 mg Cr/kg bw/day.

 

Although this value is still below the acute toxicity limit dose of 2000 mg/kg bw/day, it nevertheless demonstrates that excessive doses of trivalent chromium do not exert any signs of mortality even over a sub-chronic exposure duration. Time extrapolation using modified Haber's law is applied for the effective dose obtained in a sub-chronic study in order to conclude on the information for acute oral toxicity (for adjustment from a longer exposure duration to a shorter exposure duration the modified Haber’s rule with a default value of “n” = 3 will be used to adjust the concentration, cf. ECHA guidance R.8, Appendix 8.8, which is generally thought to be a conservative approach). Based on this extrapolation, the acute oral toxicity of dichromium nitride is considered to be above the limit dose of 2000 mg/kg bw, since chromium picolinate monohydrate has not shown any acute oral toxicity up to the limit dose.

 

The approach for read-across is decribed in detail in the document attached in IUCLID section 13.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Reference 1

Endpoint:

acute toxicity: oral

Remarks:

based on a 3-months repeated dose oral toxicity study

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2001-10-14 to 2002-01-15

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

Study had some experimental and reporting deficiencies: detailed clinical observations, ophthalmological examinations, neurobehavioural examinations and clinical chemistry examinations were missing; measure of blood clotting time/potential was missing; incomplete organ weight determinations (adrenals, uterus, ovaries, spleen, and brain were missing); histopathological examinations of the spinal cord, aorta, and peripheral nerve were missing; individual data was missing; rationale for dose selection was missing; base-line data for haematology and clinical chemistry were missing

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

no guideline followed

Principles of method if other than guideline:

Chromium picolinate monohydrate was administered ad libitum to groups of 10 male and 10 female B6C3F1 mice in feed at concentrations of 0, 80, 240, 2000, 10000 and 50000 ppm (actual ingested: males: approx. 0, 17, 50, 450, 2300 and 11900 mg/kg bw/day; females: approx. 0, 14, 40,370, 1775 and 9140 mg/kg bw/day) for up to 14 weeks. The following parameters were investigated/recorded: clinical signs, survival, body weight and gross pathology, and histopathology.

GLP compliance:

yes

Test type:

other: repeated dose oral toxicity study - 90 days

Limit test:

no

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature (~25 °C), protected from light, in sealed plastic buckets.

Stability studies of the bulk chemical were performed using ICP-AES and HPLC-UV with detection at 265 nm. These studies indicated that chromium picolinate monohydrate was stable as a bulk chemical for at least 2 weeks when stored in sealed amber glass containers at temperatures up to 60 °C. To ensure stability, the bulk chemical was stored at room temperature (~25° C), protected from light, in sealed plastic buckets. Periodic reanalyses of the bulk chemical were performed during the 3-month study using HPLC-UV, and no degradation of the bulk chemical was detected.

Species:

mouse

Strain:

B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Taconic Farms, Inc. (Germantown, NY)
- Age at study initiation: 5 to 6 weeks
- Weight at study initiation:
0 ppm group: 19.6 ± 0.2 g (males); 16.9 ± 0.2 g (females)
80 ppm group: 19.5 ± 0.3 g (males); 16.7 ± 0.4 g (females)
240 ppm group: 19.5 ± 0.3 g (males); 16.8 ± 0.2 g (females)
2000 ppm group: 19.4 ± 0.3 g (males); 16.7 ± 0.3 g (females)
10000 ppm group: 19.4 ± 0.3 g (males); 16.8 ± 0.3 g (females)
50000 ppm group: 19.6 ± 0.3 g (males); 16.9 ± 0.4 g (females)
- Housing: 1 male or 5 females per polycarbonate cage (Lab Products, Inc., Maywood, NJ; changed weekly (males) or twice weekly (females)); bedding: irradiated, heat-treated hardwood bedding chips (P.J. Murphy Forest Products, Inc., Montville, NJ; changed weekly (males) twice weekly (females)); Rack filters: Reemay® spun-bonded polyester (Andico, Birmingham, AL; changed once every 2 weeks); Racks: stainless steel (Lab Products, Maywood, NJ; changed once every 2 weeks)
- Diet (ad libitum): irradiated NTP-2000 open formula meal diet (Zeigler Brothers, Inc.,Gardners, PA)
- Water (ad libitum): tap water
- Acclimation period: 12 days (males) or 11 days (females)

Before the studies began, five male and five female mice were randomly selected for parasite evaluation and gross observation of disease. At the end of the studies, serologic analyses were performed on five male and five female control mice.

ENVIRONMENTAL CONDITIONS
- Temperature: 20.6 to 23.9 °C
- Relative humidity: 50 % ± 15 %
- Air changes: 10/hour
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

DIET PREPARATION
A premix of feed and chromium picolinate monohydrate was prepared, then layered into the remaining feed and blended in a Patterson-Kelly twin-shell blender for 30 minutes using an intensifier bar.
- Rate of preparation of diet (frequency): four times
- Storage temperature of food: stored in sealed double-thick plastic bags, protected from light at 5 °C.
- Storage time: 42 days

Doses:

0, 80, 240, 2000, 10000 and 50000 ppm (nominal) (actually ingested: males: approx. 17, 50, 450, 2300 and 11900 mg/kg bw/day; females: approx. 14, 40,370, 1775 and 9140 mg/kg bw/day)

No. of animals per sex per dose:

10 males / 10 females

Control animals:

yes

Details on study design:

NOTE: a 3-month repeated dose oral toxicity study was used in order to cover the endpoint acute oral toxicity. Therefore, the animals were observed for clinical signs, survival, and body weights during the 14 weeks treatment period. Necropsy was conducted at the end of the treatment period.

- Frequency of observations and weighing:
clinical signs: twice daily
survival: twice daily
body weights: initially, weekly, and at the end of the study
- Necropsy of survivors performed: yes

Statistics:

Survival analyses: Kaplan-Meier surivival curves, means, life table trend test, & life table pairwise comparisons. P values were two-sided.
Body weight data: parametric multiple comparison procedures of Dunnett (1955) and Williams (1971, 1972).
Jonckheere’s test was used to assess the significance of the dose-related trends and to determine whether a trend-sensitive test (Williams’ or Shirley’s test) was more appropriate for pairwise comparisons than a test that does not assume a monotonic dose-related trend (Dunnett’s or Dunn’s test). Prior to statistical analysis, extreme values identified by the outlier test of Dixon and Massey (1957) were examined, and implausible values were eliminated from the analysis.

Preliminary study:

not applicable

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

element

Remarks:

chromium

Remarks on result:

other: calculated as Cr3+

Mortality:

No mortality was observed.

Clinical signs:

other: There were no clinical findings related to exposure to chromium picolinate monohydrate; reddish-colored faeces of 50000 ppm animals were believed to be due to excretion of the test article and were not considered a sign of toxicity.

Gross pathology:

No exposure-related lesions occurred in male or female mice.

For a chemical where concentration and duration both play a role in producing an adverse effect, the magnitude of response to a chemical exposure can be correlated with both the duration of the exposure and concentration since the internal dose of a chemical at the target tissue, and therefore the response, is dependent on the combination of these components. Haber’s rule states the product of the exposure concentration (C) and exposure duration (T) required to produce an adverse effect is equal to a constant level or severity of response (K).

 

Duration adjustments are typically completed by applying Haber’s rule as modified by ten Berge (1986) as follows:

Cⁿ× T = K

For adjustment from a longer exposure duration to a shorter exposure duration the modified Haber’s rule with a default value of “n” = 3 will be used to adjust the concentration (ECHA guidance R.8, Appendix 8.8). This is generally thought to be a conservative procedure since it results in a small increase in concentration.

Using the Haber's rule, as described above, the following LD50 values were derived from the data of a 3 month repeated oral dose toxicity study (please refer to section 7.8.1 Toxicity to reproduction: Cr_k_NTP_2010_3 months_mice) conducted with male and female mice.

1) Male mice:

C (chronic) = 11900 mg/kg bw/day

t (chronic) = 98 days

t (acute) = 1 day

n = 3

Cⁿ(acute) × T = Cⁿ(chronic) × T (chronic)

C (acute) = 54864.2 mg chromium picolinate monohydrate/kg bw (equivalent to 6583.7 mg Cr/kg bw)

Therefore, the LD50 of male mice is considered to be greater than 2000 mg Chromium picolinate monohydrate/kg bw.

1) Female rats:

C = 9140 mg/kg bw/day

t (chronic) = 98 days

t (acute) = 1 day

n = 3

Cⁿ(acute) × T = Cⁿ(chronic) × T

C (acute) = 42139.4 mg chromium picolinate monohydrate/kg bw (equivalent to 5056.7 mg Cr/kg bw)

Therefore, the LD50 of female mice is considered to be greater than 2000 mg Chromium picolinate monohydrate/kg bw.

 

Interpretation of results:

GHS criteria not met

Conclusions:

LD50 (male and female mice) > 2000 mg chromium picolinate monohydrate/kg bw (based on an extrapolation from a 3-month repeated dose oral toxicity study)
LD50 (male and female mice) > 2000 mg chromium/kg bw (based on an extrapolation from a 3-month repeated dose oral toxicity study)
According to the Regulation (EC) No 1272/2008 and subsequent amendments and corrections, the substance is not classified as acute toxic via the oral route.

Reference 2

Endpoint:

acute toxicity: oral

Remarks:

based on a 3-months repeated dose oral toxicity study

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2001-10-16 to 2002-01-17

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

Study had some experimental and reporting deficiencies: detailed clinical observations, ophthalmological examinations, and neurobehavioural examinations were missing; measure of blood clotting time/potential was missing; incomplete clinical chemistry (sodium, potassium, glucose, total cholesterol, urea were missing); incomplete organ weight determinations (adrenals, uterus, ovaries, spleen, and brain were missing); histopathological examinations of the spinal cord, aorta, and peripheral nerve were missing; individual data was missing; rationale for dose selection was missing; base-line data for haematology and clinical chemistry were missing

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

no guideline followed

Principles of method if other than guideline:

Chromium picolinate monohydrate was administered ad libitum to groups of 10 male and 10 female F344/N rats in feed at concentrations of 0, 80, 240, 2000, 10000 and 50000 ppm (actually ingested: males: approx. 0, 7, 20, 160, 800 and 4240 mg/kg bw/day; females: approx. 0, 6, 20,160, 780 and 4250 mg/kg bw/day) for up to 14 weeks. The following parameters were investigated/recorded: clinical signs, survival, body weight and gross pathology.

GLP compliance:

yes

Test type:

other: repeated dose oral toxicity study - 90 days

Limit test:

no

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature (~25 °C), protected from light, in sealed plastic buckets.

Stability studies of the bulk chemical were performed using ICP-AES and HPLC-UV with detection at 265 nm. These studies indicated that chromium picolinate monohydrate was stable as a bulk chemical for at least 2 weeks when stored in sealed amber glass containers at temperatures up to 60 °C. To ensure stability, the bulk chemical was stored at room temperature (~25° C), protected from light, in sealed plastic buckets. Periodic reanalyses of the bulk chemical were performed during the 3-month study using HPLC-UV, and no degradation of the bulk chemical was detected.

Species:

rat

Strain:

other: F344/N

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Taconic Farms, Inc. (Germantown, NY)
- Age at study initiation: 5 to 6 weeks
- Weight at study initiation:
0 ppm group: 92 ± 1 g (males); 93 ± 1 g (females)
80 ppm group: 91 ± 2 g (males); 93 ± 1 g (females)
240 ppm group: 91 ± 2 g (males); 93 ± 1 g (females)
2000 ppm group: 92 ± 1 g (males); 93 ± 2 g (females)
10000 ppm group: 92 ± 1 g (males); 94 ± 1 g (females)
50000 ppm group: 92 ± 1 g (males); 93 ± 1 g (females)
- Housing: 5 animals per polycarbonate cage (Lab Products, Inc., Maywood, NJ; changed twice weekly); bedding: irradiated, heat-treated hardwood bedding chips (P.J. Murphy Forest Products, Inc., Montville, NJ; changed twice weekly); Rack filters: Reemay® spun-bonded polyester (Andico, Birmingham, AL; changed once every 2 weeks); Racks: stainless steel (Lab Products, Maywood, NJ; changed once every 2 weeks)
- Diet (ad libitum): irradiated NTP-2000 open formula meal diet (Zeigler Brothers, Inc.,Gardners, PA)
- Water (ad libitum): tap water
- Acclimation period: 13 days (males) or 14 days (females)

Before the studies began, five male and five female rats were randomly selected for parasite evaluation and gross observation of disease. At the end of the studies, serologic analyses were performed on five male and five female control rats.

ENVIRONMENTAL CONDITIONS
- Temperature: 20.6 to 23.9 °C
- Relative humidity: 50 % ± 15 %
- Air changes: 10/hour
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

DIET PREPARATION
A premix of feed and chromium picolinate monohydrate was prepared, then layered into the remaining feed and blended in a Patterson-Kelly twin-shell blender for 30 minutes using an intensifier bar.
- Rate of preparation of diet (frequency): four times
- Storage temperature of food: stored in sealed double-thick plastic bags, protected from light at 5 °C.
- Storage time: 42 days

Doses:

0, 80, 240, 2000, 10000 and 50000 ppm (nominal) (actually ingested: males: approx. 0, 7, 20, 160, 800 and 4240 mg/kg bw/day; females: approx. 6, 20,160, 780 and 4250 mg/kg bw/day)

No. of animals per sex per dose:

10 males / 10 females

Control animals:

yes

Details on study design:

NOTE: a 3-month repeated dose oral toxicity study was used in order to cover the endpoint acute oral toxicity. Therefore, the animals were observed for clinical signs, survival, and body weights during the 14 weeks treatment period. Necropsy was conducted at the end of the treatment period.

- Frequency of observations and weighing:
clinical signs: twice daily
survival: twice daily
body weights: initially, weekly, and at the end of the study
- Necropsy of survivors performed: yes

Statistics:

Survival analyses: Kaplan-Meier surivival curves, means, life table trend test, & life table pairwise comparisons. P values were two-sided.
Body weight data: parametric multiple comparison procedures of Dunnett (1955) and Williams (1971, 1972).
Jonckheere’s test was used to assess the significance of the dose-related trends and to determine whether a trend-sensitive test (Williams’ or Shirley’s test) was more appropriate for pairwise comparisons than a test that does not assume a monotonic dose-related trend (Dunnett’s or Dunn’s test). Prior to statistical analysis, extreme values identified by the outlier test of Dixon and Massey (1957) were examined, and implausible values were eliminated from the analysis.

Preliminary study:

not applicable

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

element

Remarks:

chromium

Remarks on result:

other: calculated as Cr3+

Mortality:

No mortality was observed.

Clinical signs:

other: There were no clinical findings related to exposure to chromium picolinate monohydrate; reddish-colored faeces of 50000 ppm animals were believed to be due to excretion of the test article and were not considered a sign of toxicity.

Gross pathology:

No exposure-related lesions occurred in male or female rats.

For a chemical where concentration and duration both play a role in producing an adverse effect, the magnitude of response to a chemical exposure can be correlated with both the duration of the exposure and concentration since the internal dose of a chemical at the target tissue, and therefore the response, is dependent on the combination of these components. Haber’s rule states the product of the exposure concentration (C) and exposure duration (T) required to produce an adverse effect is equal to a constant level or severity of response (K).

 

Duration adjustments are typically completed by applying Haber’s rule as modified by ten Berge (1986) as follows:

Cⁿ× T = K

For adjustment from a longer exposure duration to a shorter exposure duration the modified Haber’s rule with a default value of “n” = 3 will be used to adjust the concentration (ECHA guidance R.8, Appendix 8.8). This is generally thought to be a conservative procedure since it results in a small increase in concentration.

Using the Haber's rule, as described above, the following LD50 values were derived from the data of a 3 month repeated oral dose toxicity study (please refer to section 7.8.1 Toxicity to reproduction: Cr_k_NTP_2010_3 months_rats) conducted with male and female rats.

1) Male rats:

C (chronic) = 4240 mg/kg bw/day

t (chronic) = 98 days

t (acute) = 1 day

n = 3

Cⁿ(acute) × T = Cⁿ(chronic) × T (chronic)

C (acute) = 19548.2 mg chromium picolinate monohydrate/kg bw (equivalent to 2345.8 mg Cr/kg bw)

Therefore, the LD50 of male rats is considered to be greater than 2000 mg Chromium picolinate monohydrate/kg bw.

1) Female rats:

C = 4250 mg/kg bw/day

t (chronic) = 98 days

t (acute) = 1 day

n = 3

Cⁿ(acute) × T = Cⁿ(chronic) × T

C (acute) = 19594.4 mg chromium picolinate monohydrate /kg bw (equivalent to 2351.33 mg Cr/kg bw)

Therefore, the LD50 of female rats is considered to be greater than 2000 mg Chromium picolinate monohydrate/kg bw.

 

Interpretation of results:

GHS criteria not met

Conclusions:

LD50 (male and female rats) > 2000 mg chromium picolinate monohydrate/kg bw (based on an extrapolation from a 3-month repeated dose oral toxicity study)
LD50 (male and female rats) > 2000 mg chromium/kg bw (based on an extrapolation from a 3-month repeated dose oral toxicity study)
According to the Regulation (EC) No 1272/2008 and subsequent amendments and corrections, the substance is not classified as acute toxic via the oral route.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

weight of evidence approach

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Chromium picolinate monohydrate

Chromium picolinate monohydrate was administered in F344/N rats and B6C3F1 mice for 14 weeks in doses of up to 4240 mg/kg bw/day and 11900 mg/kg bw/day, respectively. This corresponds to a dose of 530 and 1488 mg Cr/kg bw/day. Although this value is still below the acute toxicity limit dose of 2000 mg/kg bw/day, it nevertheless demonstrates that excessive doses of trivalent chromium do not exert any signs of mortality even over a sub-chronic exposure duration. Time extrapolation using modified Haber's law is applied for the effective dose obtained in a sub-chronic study in order to conclude on the information for acute oral toxicity (for adjustment from a longer exposure duration to a shorter exposure duration the modified Haber’s rule with a default value of “n” = 3 will be used to adjust the concentration, cf. ECHA guidance R.8, Appendix 8.8, which is generally thought to be a conservative approach).Based on this extrapolation, the acute oral toxicity of dichromium nitride is considered to be above the limit dose of 2000 mg/kg bw, since chromium picolinate monohydrate has not shown any acute oral toxicity up to the limit dose. The approach for read-across is decribed in detail in the document attached in IUCLID section 13.

 

Dichromium nitride

Since no acute oral toxicity study is available specifically for dichromium nitride, information on chromium picolinate monohydrate will be used for the hazard assessment. The substance was considered to have a LD50 above the limit dose of 2000 mg/kg bw (equivalent to a LD50 above 2000 mg/kg bw for chromium). Therefore, it was concluded that dichromium nitride also has a LD50 above 2000 mg/kg bw.

A study for acute dermal toxicity was not conducted with dichromium nitride in view of the poor absorption (0.1-1%) by this route.

A study for acute toxicity via inhalation was not conducted with dichromium nitride, since it can be assumed that dichromium nitride has a low potential for human inhalation hazard during handling or application, thus acute toxic effects are not likely to occur during manufacture and handling of that substance.

For further information on the toxicity, please refer to the relevant sections in the IUCLID and CSR.

Justification for classification or non-classification

Acute oral toxicity

Dichromium nitride does not require classification for acute oral toxicity in accordance with Regulation (EC) No. 1272/2008 and subsequent amendments and corrections, since chromium picolinate monohydrate as representative of dichromium nitride, does not have a LD50 below 2000 mg/kg bw.

Furthermore, according to the criteria of REGULATION (EC) No 1272/2008 and its subsequent adaptions, dichromium nitride does not have to be classified and has no obligatory labelling requirement for specific target organ toxicity after single exposure (STOT SE, oral).