thiourea; thiocarbamide

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

supporting study

Study period:

no data

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

documentation insufficient for assessment

Qualifier:

equivalent or similar to guideline

Guideline:

other: no guideline reported

Principles of method if other than guideline:

Bioconcentration was measured by using the average constant exposure to the chemical dissolved in water (exclusive uptake through water).
BCF was measured after 3 days of exposure.
BCF (3 d) = (concentration of chemical in fish wet weight [µg/g])/(medium concentration of chemical in water [µg/g])
No further details reported.

GLP compliance:

not specified

Radiolabelling:

no

Vehicle:

no

Test organisms (species):

Leuciscus idus melanotus

Details on test organisms:

not specified

Route of exposure:

aqueous

Test type:

static

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

3 d

Hardness:

not specified

Test temperature:

not specified

pH:

not specified

Dissolved oxygen:

not specified

TOC:

not specified

Salinity:

not applicable

Conductivity:

not specified

Details on test conditions:

not specified

Nominal and measured concentrations:

not reported

Reference substance (positive control):

not specified

Details on estimation of bioconcentration:

No details reported.

Key result

Type:

BCF

Value:

< 10 dimensionless

Basis:

whole body w.w.

Remarks on result:

other: Conc.in environment / dose:not reported

Validity criteria fulfilled:

not specified

Conclusions:

The BCF of thiourea for the fish Leuciscus idus melanotus is reported to be < 10.

Executive summary:

Bioconcentration of thiourea in Leuciscus idus melanotus was measured by using the average constant exposure to the chemical dissolved in water (exclusive uptake through water). The BCF was determined after 3 days of exposure based on the following equation: BCF (3 d) = (concentration of chemical in fish wet weight [µg/g]) / (medium concentration of chemical in water [µg/g]). The BCF of thiourea for the fish Leuciscus idus melanotus is reported to be < 10.

Reference 2

Endpoint:

bioaccumulation in aquatic species, other

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

documentation insufficient for assessment

Qualifier:

equivalent or similar to guideline

Guideline:

other: no guideline reported

Principles of method if other than guideline:

Algae with dry weights of 20 mg/200 mL were exposed to 14C-labelled thiourea (50µg/L) in a 500 ml Erlenmeyer flask with glass stoppers in nutrient solution for at least 24 h at room temperature (20-25 °C). The samples were illuminated (16 hours per day) and agitated. After 24 hours the algae suspension was centrifuged (4000 rpm). Algae were removed and a hydroluma scintillation cocktail was used for counting aliquots in the water sample. The 14C activity in the algae was determined by combustion (Packard Tri Carb liquid scintillation counter model 3385).
The bioaccumulation factor was calculated as follows:
BCF (1 d) = (c(thiourea) in algae wet weight)/(final chemical concentration in water) [(µg/g algae)/(µg/g water)]

GLP compliance:

not specified

Radiolabelling:

yes

Vehicle:

no

Test organisms (species):

Chlorella fusca

Route of exposure:

aqueous

Test type:

static

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

1 d

Nominal and measured concentrations:

Nominal: 50 µg/L

Reference substance (positive control):

not required

Details on estimation of bioconcentration:

The bioaccumulation factor was calculated as follows:
BCF (1 d) = (c(thiourea) in algae wet weight)/(final chemical concentration in water) [(µg/g algae)/(µg/g water)]

Key result

Type:

BCF

Value:

54 L/kg

Basis:

whole body w.w.

Remarks on result:

other: Conc.in environment / dose:50 µg/L

Validity criteria fulfilled:

not applicable

Conclusions:

The BCF of thiourea for the alga Chlorella was determined to be 54.

Executive summary:

Algae (Chlorella) with dry weights of 20 mg/200 ml were exposed to 14C-labelled thiourea (50 µg/L) in a 500 mL Erlenmeyer flask with glass stoppers in nutrient solution for at least 24 h at room temperature (20-25 °C). The samples were illuminated (16 hours per day) and agitated. After 24 hours the algae suspension was centrifuged (4000 rpm). Algae were removed and a hydroluma scintillation cocktail was used for counting aliquots in the water sample. The 14C activity in the algae was determined by LSC (Packard Tri Carb liquid scintillation counter model 3385) following combustion.

 

The bioaccumulation factor was calculated as follows: BCF (1d) = (c(thiourea) in algae wet weight) / (final chemical concentration in water) [(µg/g algae)/(µg/g water)].

 

The BCF (1 d) for the alga Chlorella was determined to be 54 [dimensionless].

Reference 3

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1978-07-01 to 1979-03-16.

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

secondary literature

Remarks:

Original reference is not available. (NITE: Existing chemicals survey program in CSCL, Japan)

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 305 C (Bioaccumulation: Test for the Degree of Bioconcentration in Fish)

Deviations:

not specified

Principles of method if other than guideline:

Test guideline: Bioaccumulation test of a chemical substance in fish or shellfish (Bioaccumulation test).

GLP compliance:

not specified

Radiolabelling:

no

Test organisms (species):

Cyprinus carpio

Route of exposure:

aqueous

Test type:

flow-through

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

6 wk

Nominal and measured concentrations:

1st concentration area 3 ppm, 2nd concentration area 0.3 ppm

Key result

Type:

BCF

Value:

<= 0.2 dimensionless

Basis:

not specified

Remarks on result:

other: Conc.in environment / dose:3 ppm

Key result

Type:

BCF

Value:

<= 2 dimensionless

Basis:

not specified

Remarks on result:

other: Conc.in environment / dose:0,3 ppm

Validity criteria fulfilled:

not specified

Conclusions:

Thiourea has a low potential for bioaccumulation.

Executive summary:

Thiourea was tested for its bioaccumulation potential in Cyprinus carpio according to a guideline similar to OECD 305C. The substance was tested at initial concentrations of 0.3 ppm and 3 ppm for six weeks under flow-through conditions.

 

After six weeks the following results were obtained:

- Initial concentration 0.3 ppm: BCF ≤ 2

- Initial concentration 3 ppm: BCF ≤ 0.2

 

Therefore, thiourea was assessed as having a low potential for bioaccumulation.

Reference 4

Endpoint:

bioaccumulation in aquatic species: fish

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because the substance has a low potential for bioaccumulation based on log Kow <=3

Description of key information

No reliable studies (Klimisch score 1 or 2) are available for thiourea.

However, a new reliable bioaccumulation in aquatic species study does not need to be conducted, as in accordance with column 2 of REACH Annex IX the substance has a low potential for bioaccumulation (log octanol water partition coefficient less than 3).
This is further supported by two studies (both with reliability score 3) conducted by Geyer et al. (1984) and Freitag et al. (1985) examining bioconcentration in algae (Chlorella) and fish (Leuciscus idus melanotus) after 1 and 3 days, respectively. The BCF (1 d) for the alga Chlorella was determined to be 54. The BCF (3 d) of thiourea for the fish Leuciscus idus melanotus is reported to be < 10.
In addition, the study available in the context of the existing chemicals survey program in CSCL, Japan (NITE) demonstrates a BCF for Cyprinus carpio in the range of < 0.2 to < 2.
Therefore, it can be concluded that thiourea does not have a significant potential for bioaccumulation.

Key value for chemical safety assessment

BCF (aquatic species):

54 dimensionless

Additional information

Studies with a reliability score of 1 or 2 (Klimisch) that might be used in the assessment of thiourea are not available. Nonetheless, a new reliable bioaccumulation study in aquatic species does not need to be conducted, as in accordance with column 2 of REACH Annex IX the substance has a low potential for bioaccumulation (the substance has a log octanol-water partition coefficient less than 3).

However, two studies with a reliability score fo 3 conducted by Geyer et al. (1984) and Freitag et al. (1985), as well as one study rated "4" (NITE) are available that support the waiving argument:

Geyer et al. (1985) exposed algae (Chlorella) with dry weights of 20 mg/200 ml to 14C-labelled thiourea (50 µg/L) in 500 mL Erlenmeyer flasks with glass stoppers in nutrient solution for at least 24 h at room temperature (20-25 °C). The samples were illuminated (16 hours per day) and agitated. After 24 hours the algae suspension was centrifuged (4000 rpm). Algae were removed and a hydroluma scintillation cocktail was used for counting radioactivity in the water sample. The 14C activity in the algae was determined by LSC after combustion (Packard Tri Carb liquid scintillation counter model 3385).

The bioaccumulation factor was calculated as follows:

BCF (1 d) = (c(thiourea) in algae wet weight) / (final chemical concentration in water) [(µg/g algae) / (µg/g water)].

The BCF (1 d) for the alga Chlorella was determined to be 54.

Freitag et al. (1985) determined the bioconcentration of thiourea in the fish Leuciscus idus melanotus via the average constant exposure to the chemical dissolved in water (exclusive uptake through water). The BCF was determined after 3 days of exposure using the following equation:

BCF (3 d) = (concentration of chemical in fish wet weight [µg/g]) / (medium concentration of chemical in water [µg/g])

The BCF of thiourea for the fish Leuciscus idus melanotus is reported to be < 10.

In the context of the "Existing chemicals survey program" in CSCL, Japan (NITE) one study is available where thiourea was tested for its bioaccumulation potential in Cyprinus carpio according to a guideline similar to OECD 305C. The substance was tested at initial concentrations of 0.3 ppm and 3 ppm for six weeks under flow-through conditions.

After six weeks the following results were obtained:

- Initial concentration 0.3 ppm: BCF ≤ 2

- Initial concentration 3 ppm: BCF ≤ 0.2

Due to the information and results presented above, it can be concluded that thiourea does not have a significant potential for bioaccumulation. The highest value of BCF = 54 is used as key value in the risk assessment, following a worst case approach.