(2Z)-2-phenylhex-2-enenitrile

Toxicological Summary

Workers - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

2.351 mg/m³

Most sensitive endpoint:

developmental toxicity / teratogenicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

75

Dose descriptor starting point:

NOAEL

Value:

200 mg/kg bw/day

Modified dose descriptor starting point:

NOAEC

Value:

176.3 mg/m³

Explanation for the modification of the dose descriptor starting point:

Regarding absorption, in the absence of reliable data for both the starting route (oral) and the end route (inhalation), worst case assumptions were made. It was assumed that a limited absorption occurs by the oral route, leading to a low (conservative) internal NOAEL. To secure a conservative external NOAEL, a maximum absorption should be assumed for the inhalation route (i.e.; 100%) leading to a low external NOAEL. Thus, in the case of oral-to-inhalation extrapolation, it is proposed to include a default factor of 2, i.e. the absorption percentage by oral route is half that of the inhalation absorption as suggested in ECHA Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.8 (2012).

To convert the oral NOAEL into inhalatory NOAEC, a rat default respiratory volume was used corresponding to the daily duration of human exposure (sRVrat: 0.38 m3/kg bw/8 h). For workers a correction was added for the difference between respiratory rates under standard conditions (sRVhuman: 6.7 m3 for an 8-h exposure period) and under conditions of light activity (wRV: 10 m3 for an 8-h exposure period). Thus, the corrected dose descriptor for inhalation is [200 mg/kg bw/day] X  [1/0.38 m3/kg bw/day] X [1/2] X [6.7 m3/10m3]. Thus, the corrected dose descriptor for inhalation is 176.3 mg/m3 for workers.

AF for dose response relationship:

1

Justification:

The dose-descriptor is a NOAEL. Table R.8-6 ECHA REACH Guidance

AF for differences in duration of exposure:

6

Justification:

Default factor for a sub-acute study. Table R.8-5 ECHA REACH Guidance

AF for interspecies differences (allometric scaling):

1

Justification:

Table R.8-4 ECHA REACH Guidance. Assessment factor not to be used for inhalation route since the differences in the metabolic rate/bw has already been taken into account in the corrected dose descriptor.

AF for other interspecies differences:

2.5

Justification:

Default factor for other interspecies differences. Table R.8-6 ECHA REACH Guidance

AF for intraspecies differences:

5

Justification:

Default factor for worker. Table R.8-6 ECHA REACH Guidance

AF for the quality of the whole database:

1

Justification:

Default factor for good/standard quality of the database taken into account completeness of the standard information requirements for the tonnage band

AF for remaining uncertainties:

1

Justification:

No remaining uncertainties

Acute/short term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

2.351 mg/m³

Most sensitive endpoint:

developmental toxicity / teratogenicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

75

DNEL extrapolated from long term DNEL

Dose descriptor starting point:

NOAEL

Value:

200 mg/kg bw/day

Modified dose descriptor starting point:

NOAEC

Value:

176.3 mg/m³

Explanation for the modification of the dose descriptor starting point:

In accordance with ECHA Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.8 (2012), Appendix R.8 -8 Acute Toxicity, as acute inhalation hazards have been identified but the acute inhalation toxicity test (OECD 403) resulted in no usable quantitative data, as large uncertainties are expected due to the test (OECD 403) value being a less than value, the DNEL should be based on long term studies. As no long-term inhalation studies were available and due to the uncertainty in deriving an acute DNEL, a DNEL is presented that will allow a qualitative risk assessment.  In line with ECHA recommendations (Chapter R.8) the OCs/RMMs presented in the risk assessment should ensure that peak concentrations exceeding the long-term DNEL will not occur. In most instances this is considered conservative and protective of both long-term and short-term effects as long-term effects will occur at lower concentrations of the substance, as such the long-term DNEL is lower than the acute DNEL. Therefore, the long-term inhalatory DNEL was used as a surrogate. The long-term inhalatory DNEL was estimated as per Inhalation Systemic effects - Long-term.

AF for dose response relationship:

1

Justification:

The dose-descriptor is a NOAEL. Table R.8-6 ECHA REACH Guidance.

AF for interspecies differences (allometric scaling):

1

Justification:

Table R.8-4 ECHA REACH Guidance. Assessment factor not to be used for inhalation route since the differences in the metabolic rate/bw has already been taken into account in the corrected dose descriptor.

AF for other interspecies differences:

2.5

Justification:

Default factor for other interspecies differences. Table R.8-6 ECHA REACH Guidance.

AF for intraspecies differences:

5

Justification:

Default factor for worker. Table R.8-6 ECHA REACH Guidance.

AF for the quality of the whole database:

1

Justification:

Default factor for good/standard quality of the database taken into account completeness of the standard information requirements for the tonnage band.

AF for remaining uncertainties:

6

Justification:

Default factor for a sub-acute study. Table R.8-5 ECHA REACH Guidance.
A DNEL for acute inhalation cannot be derived from the current data set. In line with ECHA guidance (Chapter R.8, 2012) the long-term DNEL for oral is used as there is a lack of information on the inhalation route. In order to derive the DNEL, the NOAEL must be corrected for differences in time between sub-acute and chronic toxicity. The section for the assessment factor of the correction for duration does not exist in IUCLID for acute end points. In this instance the duration differences are addressed in remaining uncertainties.

Local effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

Workers - Hazard via dermal route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

0.667 mg/kg bw/day

Most sensitive endpoint:

developmental toxicity / teratogenicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

300

Dose descriptor starting point:

NOAEL

Value:

200 mg/kg bw/day

Modified dose descriptor starting point:

NOAEL

Value:

200 mg/kg bw/day

Explanation for the modification of the dose descriptor starting point:

For potential dermal exposure, route-to-route extrapolation from the oral NOAEL value was considered appropriate. Since a maximal absorption already occurred by oral route, no additional factor was introduced.

AF for dose response relationship:

1

Justification:

The dose-descriptor is a NOAEL. Table R.8-6 ECHA REACH Guidance.

AF for differences in duration of exposure:

6

Justification:

Default factor for a sub-acute study. Table R.8-5 ECHA REACH Guidance.

AF for interspecies differences (allometric scaling):

4

Justification:

Default allometric scaling factor for rats. Table R.8-4 ECHA REACH Guidance.

AF for other interspecies differences:

2.5

Justification:

Default factor for other interspecies differences. Table R.8-6 ECHA REACH Guidance.

AF for intraspecies differences:

5

Justification:

Default factor for worker. Table R.8-6 ECHA REACH Guidance.

AF for the quality of the whole database:

1

Justification:

Default factor for good/standard quality of the database taken into account completeness of the standard information requirements for the tonnage band

AF for remaining uncertainties:

1

Justification:

No remaining uncertainties.

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

medium hazard (no threshold derived)

Acute/short term exposure

Hazard assessment conclusion:

medium hazard (no threshold derived)

Workers - Hazard for the eyes

Local effects

Hazard assessment conclusion:

no hazard identified

Additional information - workers


As no reliable and relevant acute LC50 value was derived for inhalation, and due to the effects observed long-term orally, for risk assessment, the NOAEL from the most sensitive long-term endpoint was used, i.e. 200 mg/gg bw/day from OECD 421 study (oral administration). This was based on clinical observations in both sexes and reduced food consumption and lower body weight gain in female which resulted in lower body weight gain in pups. It should be noted that similar effects were seen in another study OECD 407 which is also detailed below.

In a sub-acute study following the OECD 422 guideline, (2Z)-2-phenylhex-2-enenitrile was given orally by gavage for a minimum of 28 days to Wistar Han rats at doses of 0, 60, 200, 600 mg/kg/day.

No mortality occurred during the study period that was considered to be related to treatment. Piloerection was noted in females at dose 600 mg/kg and occurred in one female from week 1-3 of treatment and in several females from approximately Week 5 until Week 7 of treatment. Yellow discolouration of the urine was observed in most males and females at dose 600 mg/kg from Week 1 (males) and Week 2 (females) of treatment.

Lower body weight gain was observed in male treated at 600 mg/kg bw/day throughout the study, in female of the same dose group, lower body was observed at start of mating and directly after delivery. This correlated with reduction in absolute food consumption observed at high dose group.

Clinical biochemical changes included dose dependently reduction in Serum levels of T4 in F0-males and females at all does groups, albeit, the reported values were within laboratory historical control range and as such not considered adverse.

There were no test item-related alterations in organs including reproductive organs weights of either sex up to 600 mg/kg, however, macroscopic findings in the liver (red-brown discoloration) was noted in 4/10 males at 600 mg/kg/day, without any microscopic correlation.

Reproductive parameters such as fertility index, length and regularity of the estrous cycle, mating index, precoital time, mean and number of implantation sites  were considered unaffected by treatment.

Developmental parameters such as gestation index and duration of gestation, parturition/maternal care, post-implantation survival index, litter size and live litter size, live birth indices, sex ratio viability index and lactation index were unaffected by the treatment.

No clinical signs occurred among pups that were considered to be related to treatment. At 600 mg/kg, body weights of pups were lower from postnatal Day (PND) 1 in males, females and for males and females combined.  Body weights were approximately 9-13% lower on PND 1 and approximately 13-18% lower on the following days up to PND 13 when compared with the concurrent controls. Anogenital distance (absolute and normalized for body weight) and areola/nipple retention in pups were considered not to be affected by treatment. No changes in clinical biochemistry of serum T4 levels in male and female PND 14-16 pups. No macroscopic or microscopic changes where noted in pups.

In conclusion, based on the results of this reproduction/developmental toxicity screening test, the following no-observed-adverse-effect level (NOAEL) of (2Z)-2-phenylhex-2-enenitrile were established; parental NOAEL200 mg/kg bw/day (based on clinical signs and changes in body weight gain, reproductive NOAEL at least 600 mg/kg bw/day and developmental NOAEL of 200 mg/kg bw/day (based on reduced body weight of pups at 600 mg/kg bw/day).

In adition to the above, previous sub-chronic study, the systemic toxic potential of the substance was evaluated in SPF-bred Wistar rats. Groups of 5 animal per sex were administered daily oral dose of  60, 200 and 600 mg/kg body weight for a period of 28 days (OECD 407; Firmenich 2009). This was followed by 14 – day treatment free recovery period. No test item-related mortalities were noted during treatment or recovery period. No test item-related mortalities were noted during treatment or recovery period with exception of one female death in control group. No findings were noted in the functional observation batter, mean grip strength or locomotive activities. Salivation was noted in all animals in all dose groups and dyspnea was sporadically noted in animals at 200 and 600 mg/kg/day. These observation were reversible and without any associated macroscopic or microscopic findings at necropsy.

Increased absolute and relative food consumption at 600 mg/kg/day during treatment and recovery period. These findings correlated with slightly decreased mean absolute and relative body weights in high dose animals during treatment period or at the beginning of recovery period in a compensatory manner and were therefore considered to be not adverse.

Reversible decrease of absolute and relative body weights at 600 mg/kg/day during treatment period and increase of relative body weights at the end of recovery period.

No test substance related changes in haematology parameters were noted in animals at 60 mg/kg/day. Reversible observed  haematological changes included; elevated mean corpuscular volume (MCV), decreased mean corpuscular haemoglobin concentration (MCHC), decreased haemoglobin distribution width (HDW), elevated reticulocytes in both sexes and additionally changes in prothrombin and partial thromboplastin time (PT and PTT) in females at 600 mg/kg/day and elevated reticulocytes in both sexes at 200 mg/kg/day along with decreased haemoglobin in males and decreased haemoglobin distribution width in females at 200 mg/kg/day Theses correlated microscopically with increased haematopoiesis in the spleen in 5/5 males and 3/5 females treated with 600 mg/kg/day (group 4) and 5/5 males and 3/5 females treated with 200 mg/kg/day (group 3) compared to controls. No microscopical findings in the spleen were noted after recovery period anymore. Generally, changes in the red blood cell parameters like MCV, MCHC, HDW and reticulocytes were considered to be indicative for an anaemic, most likely hemolytic, occurrence during the treatment period. Elevated relative and absolute reticulocytes along with elevated H-reticulocytes were considered to clearly reflect a compensatory response and adaption to this occurrence. This consideration was supported by the fact, that the red blood cell count (RBC), hematocrit (HCT), mean corpuscular haemoglobin (MCH) in all dose groups along with haemoglobin (HB) in the high dose groups did not show any significant reduction after treatment or recovery period. The changes in haematology parameters were therefore considered to be test item-related, but of non-adverse character and reversible.

Reversible changes in biochemistry included decreased glucose & creatinine in both sexes, decreased chloride (females), elevated bilirubin, alanine aminotransferase (ALAT),  potassium, protein in both sexes, urea (males) and sodium (males) in both sexes, elevated calcium, phosphorus and albumin (males), elevated cholesterin and triglycerides (female) at 600 mg/kg/day. Elevated bilirubin and ALAT was considered to be possibly connected to changes of centrilobular hypertrophy noted in the liver in histopathology which were not noted after recovery period anymore. Due to reversibility after recovery period, the changes in biochemistry parameters were considered to be not adverse.

Reversible changes in urinalysis were; elevated relative density, elevated protein, ketones, urobilinogen and leucocytes with changes in colour and appearance at 200 and 600 mg/kg/day and elevated leucocytes at 60 mg/kg/day.

Reversible changes in organ weights noted included; elevated absolute and relative liver  and absolute kidney weights in both sexes  in all dose groups, elevated relative kidney weights in both sexes at 200 and 600 mg/kg/day and females at 60 mg/kg/day. Slightly increased liver and kidneys to body weight ratios in females after recovery period were markedly reduced compared to values of high dose females at week 4 and also comparable to control. Macroscopic included enlarged liver in one male at 200 and 600 mg/kg/day. Microscopic findings were centrilobular hypertrophy in the liver, increased hematopoiesis in the spleen and tubular hypertrophy in the kidneys at 200 and 600 mg/kg/day.  Based on the results of this study, it was not possible to set a no-observed-effect-level (NOEL). The no-observed-adverse-effect-level (NOAEL) for ST 18 C 08 was above 600 mg/kg/day, the highest dose level tested in this study.

Based on the observation in the two studies, similar effects were noted. However, based on the recovery groups in the OECD 407, these effects were reversible. Nonetheless, taking a conservative apprached the NOAEL of 200 mg/kg bw/day was considered appropriate as there was no recovery group in the OECD 421 and as such, no conclusion can be made whether observations under the study were reversible.

General Population - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

0.58 mg/m³

Most sensitive endpoint:

developmental toxicity / teratogenicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

150

Dose descriptor starting point:

NOAEL

Value:

200 mg/kg bw/day

Modified dose descriptor starting point:

NOAEC

Value:

86.97 mg/m³

Explanation for the modification of the dose descriptor starting point:

Regarding absorption, in the absence of reliable data for both the starting route (oral) and the end route (inhalation), worst case assumptions were made. It was assumed that a limited absorption occurs by the oral route, leading to a low (conservative) internal NOAEL. To secure a conservative external NOAEL, a maximum absorption should be assumed for the inhalation route (i.e.; 100%) leading to a low external NOAEL. Thus, in the case of oral-to- inhalation extrapolation, it is proposed to include a default factor of 2, i.e. the absorption percentage by oral route is half that of the inhalation absorption as suggested in ECHA Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.8 (2012). To convert the oral NOAEL into inhalatory NOAEC, a rat default respiratory volume was used corresponding to the daily duration of human exposure (sRVrat: 1.15 m3/kg bw/24 h). Thus, the corrected dose descriptor for inhalation is [200 mg/kg bw/day] x [1/1.15 m3/kg bw/ day] x [1/2]. Thus, the corrected dose descriptor for inhalation is 86.97 mg/m3 for the general population.

AF for dose response relationship:

1

Justification:

The dose-descriptor is a NOAEL. Table R.8-6 ECHA REACH Guidance.

AF for differences in duration of exposure:

6

Justification:

Default factor for a sub-acute. Table R.8-5 ECHA REACH Guidance.

AF for interspecies differences (allometric scaling):

1

Justification:

Table R.8-4 ECHA REACH Guidance. Assessment factor not to be used for inhalation route since the differences in metabolic rate/bw has already been taken into account for the corrected dose descriptor.

AF for other interspecies differences:

2.5

Justification:

Default factor for other interspecies differences. Table R.8-6 ECHA REACH Guidance

AF for intraspecies differences:

10

Justification:

Default factor for general population. Table R.8-6 ECHA REACH Guidance

AF for the quality of the whole database:

1

Justification:

Default factor for good/standard quality of the database taken into account completeness of the standard information requirements for the tonnage band.

AF for remaining uncertainties:

1

Justification:

No remaining uncertainties

Acute/short term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

0.58 mg/m³

Most sensitive endpoint:

developmental toxicity / teratogenicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

150

DNEL extrapolated from long term DNEL

Dose descriptor starting point:

NOAEL

Value:

200 mg/kg bw/day

Modified dose descriptor starting point:

NOAEC

Value:

86.97 mg/m³

Explanation for the modification of the dose descriptor starting point:

In accordance with ECHA Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.8 (2012), Appendix R.8 -8 Acute Toxicity, as acute inhalation hazards have been identified but the acute inhalation toxicity test (OECD 403) resulted in no usable quantitative data, as large uncertainties are expected due to the test (OECD 403) value being a less than value, the DNEL should be based on long term studies. As no long-term inhalation studies were available and due to the uncertainty in deriving an acute DNEL, a DNEL is presented that will allow a qualitative risk assessment.  In line with ECHA recommendations (Chapter R.8) the OCs/RMMs presented in the risk assessment should ensure that peak concentrations exceeding the long-term DNEL will not occur. In most instances this is considered conservative and protective of both long-term and short-term effects as long-term effects will occur at lower concentrations of the substance, as such the long-term DNEL is lower than the acute DNEL. Therefore, the long-term inhalatory DNEL was used as a surrogate. The long-term inhalatory DNEL was estimated as per Inhalation Systemic effects - Long-term.

AF for dose response relationship:

1

Justification:

The dose-descriptor is a NOAEL. Table R.8-6 ECHA REACH Guidance.

AF for interspecies differences (allometric scaling):

1

Justification:

Table R.8-4 ECHA REACH Guidance. Assessment factor not to be used for inhalation route since the differences in metabolic rate/bw has already been taken into account for the corrected dose descriptor.

AF for other interspecies differences:

2.5

Justification:

Default factor for other interspecies differences. Table R.8-6 ECHA REACH Guidance

AF for intraspecies differences:

10

Justification:

Default factor for general population. Table R.8-6 ECHA REACH Guidance

AF for the quality of the whole database:

1

Justification:

Default factor for good/standard quality of the database taken into account completeness of the standard information requirements for the tonnage band.

AF for remaining uncertainties:

6

Justification:

Default factor for a sub-acute study. Table R.8-5 ECHA REACH Guidance.
A DNEL for acute inhalation cannot be derived from the current data set. In line with ECHA guidance (Chapter R.8, 2012) the long-term DNEL for oral is used as there is a lack of information on the inhalation route. In order to derive the DNEL, the NOAEL must be corrected for differences in time between sub-acute and chronic toxicity. The section for the assessment factor of the correction for duration does not exist in IUCLID for acute end points. In this instance the duration differences are addressed in remaining uncertainties.

Local effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

General Population - Hazard via dermal route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

0.333 mg/kg bw/day

Most sensitive endpoint:

developmental toxicity / teratogenicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

600

Dose descriptor starting point:

NOAEL

Value:

200 mg/kg bw/day

Modified dose descriptor starting point:

NOAEL

Value:

200 mg/kg bw/day

Explanation for the modification of the dose descriptor starting point:

For potential dermal exposure, route-to-route extrapolation from the oral NOAEL value was considered appropriate. Since a maximal absorption already occurred by oral route, no additional factor was introduced.

AF for dose response relationship:

1

Justification:

The dose-descriptor is a NOAEL. Table R.8-6 ECHA REACH Guidance

AF for differences in duration of exposure:

6

Justification:

Default factor for a sub-acute study. Table R.8-5 ECHA REACH Guidance.

AF for interspecies differences (allometric scaling):

4

Justification:

Default allometric scaling factor for rats. Table R.8-4 ECHA REACH Guidance.

AF for other interspecies differences:

2.5

Justification:

Default factor for other interspecies differences. Table R.8-6 ECHA REACH Guidance.

AF for intraspecies differences:

10

Justification:

Default factor for general population. Table R.8-6 ECHA REACH Guidance.

AF for the quality of the whole database:

1

Justification:

Default factor for good/standard quality of the database taken into account completeness of the standard information requirements for the tonnage band.

AF for remaining uncertainties:

1

Justification:

No remaining uncertainties

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

medium hazard (no threshold derived)

Acute/short term exposure

Hazard assessment conclusion:

medium hazard (no threshold derived)

General Population - Hazard via oral route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

0.333 mg/kg bw/day

Most sensitive endpoint:

developmental toxicity / teratogenicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

other:

Overall assessment factor (AF):

600

Dose descriptor starting point:

NOAEL

Value:

200 mg/kg bw/day

Modified dose descriptor starting point:

NOAEL

Value:

200 mg/kg bw/day

Explanation for the modification of the dose descriptor starting point:

The calculation of the DNELs is performed in accordance with the principles given in ECHA Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.8 (2012). NOAEL of 200 mg/kg bw/day for systemic effects established in a repeated (sub-chronic) dose toxicity study (OECD 422) in rats. No modification of the dose descriptor starting point is required. The endpoint used to derive the DNEL uses the oral route for exposure.

AF for dose response relationship:

1

Justification:

The dose-descriptor is a NOAEL. Table R.8-6 ECHA REACH Guidance.

AF for differences in duration of exposure:

6

Justification:

Default factor for a sub-acute study. Table R.8-5 ECHA REACH Guidance.

AF for interspecies differences (allometric scaling):

4

Justification:

Default allometric scaling factor for rats. Table R.8-4 ECHA REACH Guidance.

AF for other interspecies differences:

2.5

Justification:

Default factor for other interspecies differences. Table R.8-6 ECHA REACH Guidance.

AF for intraspecies differences:

10

Justification:

Default factor for good/standard quality of the database taken into account completeness, consistency and the standard information requirements for the tonnage band.

AF for the quality of the whole database:

1

Justification:

Default factor for good/standard quality of the database taken into account completeness of the standard information requirements for the tonnage band.

AF for remaining uncertainties:

1

Justification:

No remaining uncertainties.

Acute/short term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

1 mg/kg bw/day

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

600

DNEL extrapolated from long term DNEL

Dose descriptor starting point:

NOAEL

Value:

600 mg/kg bw/day

Modified dose descriptor starting point:

NOAEL

Value:

600 mg/kg bw/day

Explanation for the modification of the dose descriptor starting point:

The acute oral toxicity resulted into an LC50 of >300 - 2000 mg/kg bw  i.e. classified as Category 4 in accordance with UN GHS & CLP regulation,  according to the ECHA Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.8, Appendix R 8.8 (Version 2.1, November 2012), although, peak exposures in theory may also occur for oral routes, usually this is not normally assessed, however, the substance is used in consumer product and as such acute oral toxicity hazard need to accessed.

Therefore, the DNEL for acute toxicity is derived in the same way as the DNEL for long-term toxicity in accordance with the principles given in ECHA Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.8 (2012). NOAEL of 200 mg/kg bw/day for systemic effects established in a repeated (sub-chronic) dose toxicity study (OECD 422) in rats. The extrapolation of long to short term risk was set based on a reference period of 15 minutes at 1-5 times the value (default 3) of the long-term Oral DNEL . i.e. 0.3333 mg/kg bw/day * 3.

AF for dose response relationship:

1

Justification:

The dose-descriptor is a NOAEL. Table R.8-6 ECHA REACH Guidance

AF for interspecies differences (allometric scaling):

4

Justification:

Default allometric scaling factor for rats. Table R.8-4 ECHA REACH Guidance.

AF for other interspecies differences:

2.5

Justification:

Default factor for other interspecies differences. Table R.8-6 ECHA REACH Guidance.

AF for intraspecies differences:

10

Justification:

Default factor for general population. Table R.8-6 ECHA REACH Guidance.

AF for the quality of the whole database:

1

Justification:

Default factor for good/standard quality of the database taken into account completeness of the standard information requirements for the tonnage band.

AF for remaining uncertainties:

6

Justification:

Default factor for a sub-acute study. Table R.8-5 ECHA REACH Guidance.

General Population - Hazard for the eyes

Local effects

Hazard assessment conclusion:

no hazard identified

Additional information - General Population

For risk assessment, NOAEL from the most sensitive endpoint was used, i.e. 200 mg/gg bw/day from OECD 421 study, this was based on clinical observations in both sex and reduced food consumption and lower body weight gain in female which resulted in lower body weight gain in pups. It should be noted that similar effects were seen in another study OECD 407 albeit reversibility was noted as detailed below.

 

In a sub-acute study following the OECD 422 guideline, (2Z)-2-phenylhex-2-enenitrile was given orally by gavage for a minimum of 28 days to Wistar Han rats at doses of 0, 60, 200, 600 mg/kg/day.

No mortality occurred during the study period that was considered to be related to treatment. Piloerection was noted in females at dose 600 mg/kg and occurred in one female from week 1-3 of treatment and in several females from approximately Week 5 until Week 7 of treatment. Yellow discolouration of the urine was observed in most males and females at dose 600 mg/kg from Week 1 (males) and Week 2 (females) of treatment.

Lower body weight gain was observed in male treated at 600 mg/kg bw/day throughout the study, in female of the same dose group, lower body was observed at start of mating and directly after delivery. This correlated with reduction in absolute food consumption observed at high dose group.

Clinical biochemical changes included dose dependently reduction in Serum levels of T4 in F0-males and females at all does groups, albeit, the reported values were within laboratory historical control range and as such not considered adverse.

There were no test item-related alterations in organs including reproductive organs weights of either sex up to 600 mg/kg, however, macroscopic findings in the liver (red-brown discoloration) was noted in 4/10 males at 600 mg/kg/day, without any microscopic correlation.

Reproductive parameters such as fertility index, length and regularity of the estrous cycle, mating index, precoital time, mean and number of implantation sites were considered unaffected by treatment.

Developmental parameters such as gestation index and duration of gestation, parturition/maternal care, post-implantation survival index, litter size and live litter size, live birth indices, sex ratio viability index and lactation index were unaffected by the treatment.

No clinical signs occurred among pups that were considered to be related to treatment. At 600 mg/kg, body weights of pups were lower from postnatal Day (PND) 1 in males, females and for males and females combined.  Body weights were approximately 9-13% lower on PND 1 and approximately 13 -18% lower on the following days up to PND 13 when compared with the concurrent controls. Anogenital distance (absolute and normalized for body weight) and areola/nipple retention in pups were considered not to be affected by treatment. No changes in clinical biochemistry of serum T4 levels in male and female PND 14-16 pups. No macroscopic or microscopic changes where noted in pups.

In conclusion, based on the results of this reproduction/developmental toxicity screening test, the following no-observed-adverse-effect level (NOAEL) of (2Z)-2-phenylhex-2-enenitrile were established; parental NOAEL200 mg/kg bw/day (based on clinical signs and changes in body weight gain, reproductive NOAEL at least 600 mg/kg bw/day and developmental NOAEL of 200 mg/kg bw/day (based on reduced body weight of pups at 600 mg/kg bw/day).

 

In addition to the above, in a previous sub-chronic study, the systemic toxic potential of the substance was evaluated in SPF-bred Wistar rats. Groups of 5 animal per sex were administered daily oral dose of 60, 200 and 600 mg/kg body weight for a period of 28 days (OECD 407; Firmenich 2009). This was followed by 14 – day treatment free recovery period. No test item-related mortalities were noted during treatment or recovery period. No test item-related mortalities were noted during treatment or recovery period with exception of one female death in control group. No findings were noted in the functional observation batter, mean grip strength or locomotive activities. Salivation was noted in all animals in all dose groups and dyspnea was sporadically noted in animals at 200 and 600 mg/kg/day. These observations were reversible and without any associated macroscopic or microscopic findings at necropsy. Increased absolute and relative food consumption at 600 mg/kg/day during treatment and recovery period. These findings correlated with slightly decreased mean absolute and relative body weights in high dose animals during treatment period or at the beginning of recovery period in a compensatory manner and were therefore considered to be not adverse. Reversible decrease of absolute and relative body weights at 600 mg/kg/day during treatment period and increase of relative body weights at the end of recovery period.

No test substance related changes in haematology parameters were noted in animals at 60 mg/kg/day. Reversible observed  haematological changes included; elevated mean corpuscular volume (MCV), decreased mean corpuscular haemoglobin concentration (MCHC), decreased haemoglobin distribution width (HDW), elevated reticulocytes in both sexes and additionally changes in prothrombin and partial thromboplastin time (PT and PTT) in females at 600 mg/kg/day and elevated reticulocytes in both sexes at 200 mg/kg/day along with decreased haemoglobin in males and decreased haemoglobin distribution width in females at 200 mg/kg/day Theses correlated microscopically with increased haematopoiesis in the spleen in 5/5 males and 3/5 females treated with 600 mg/kg/day (group 4) and 5/5 males and 3/5 females treated with 200 mg/kg/day (group 3) compared to controls. No microscopical findings in the spleen were noted after recovery period anymore. Generally, changes in the red blood cell parameters like MCV, MCHC, HDW and reticulocytes were considered to be indicative for an anaemic, most likely hemolytic, occurrence during the treatment period. Elevated relative and absolute reticulocytes along with elevated H-reticulocytes were considered to clearly reflect a compensatory response and adaption to this occurrence. This consideration was supported by the fact, that the red blood cell count (RBC), hematocrit (HCT), mean corpuscular haemoglobin (MCH) in all dose groups along with haemoglobin (HB) in the high dose groups did not show any significant reduction after treatment or recovery period. The changes in haematology parameters were therefore considered to be test item-related, but of non-adverse character and reversible.

Reversible changes in biochemistry included decreased glucose & creatinine in both sexes, decreased chloride (females), elevated bilirubin, alanine aminotransferase (ALAT),  potassium, protein in both sexes, urea (males) and sodium (males) in both sexes, elevated calcium, phosphorus and albumin (males), elevated cholesterin and triglycerides (female) at 600 mg/kg/day. Elevated bilirubin and ALAT was considered to be possibly connected to changes of centrilobular hypertrophy noted in the liver in histopathology which were not noted after recovery period anymore. Due to reversibility after recovery period, the changes in biochemistry parameters were considered to be not adverse.

Reversible changes in urinalysis were; elevated relative density, elevated protein, ketones, urobilinogen and leucocytes with changes in colour and appearance at 200 and 600 mg/kg/day and elevated leucocytes at 60 mg/kg/day.

Reversible changes in organ weights noted included; elevated absolute and relative liver  and absolute kidney weights in both sexes  in all dose groups, elevated relative kidney weights in both sexes at 200 and 600 mg/kg/day and females at 60 mg/kg/day. Slightly increased liver and kidneys to body weight ratios in females after recovery period were markedly reduced compared to values of high dose females at week 4 and also comparable to control. Macroscopic included enlarged liver in one male at 200 and 600 mg/kg/day. Microscopic findings were centrilobular hypertrophy in the liver, increased hematopoiesis in the spleen and tubular hypertrophy in the kidneys at 200 and 600 mg/kg/day.  Based on the results of this study, it was not possible to set a no-observed-effect-level (NOEL). The no-observed-adverse-effect-level (NOAEL) for the test item was above 600 mg/kg/day, the highest dose level tested in the study.

Based on the observation(s) in the two studies, similar effects were noted. However, based on the recovery groups in the OECD 407, these effects were reversible. Nonetheless, taking a conservative apprached the NOAEL of 200 mg/kg bw/day was considered appropriate as there was no recovery group in the OECD 421 and as such, no conclusion can be made whether observations under the study were reversible.