Choline chloride

Toxicological Summary

Workers - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

194.54 mg/m³

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

1

Dose descriptor starting point:

other: AI

Value:

6.67 mg/kg bw/day

Modified dose descriptor starting point:

other: corr. AI

Value:

194.54 mg/m³

Explanation for the modification of the dose descriptor starting point:

The Adequate Intake (AI) of 6.67 mg/kg bw/day corresponding to 194.54 mg/m³ derived from the EFSA Panel on Dietetic Products, Nutrition and allergies (NDA, 2016; doi: 10.2903/j.efsa.2016.4484) for Choline is considered as the most conservative dose descriptor for the DNEL derivation.

 

Derivation of corrected AI: 6.67 mg/kg bw/day * (1/0.096 m³ / kg bw/day) * (6.7 m³ / 10 m³) * (50 % / 25 %) * (7 d/ 5d) = 194.54 mg/m³

In detail, an oral absorption of 50 % and absorption by inhalation of 25 %, the sRV (standard respiratory volume of humans during 8 hours) of 0.096 m³/kg/day and a factor of 0.67 (derived of the standard respiratory volumes for workers under normal conditions and by light activity: 6.7 m³ and 10 m³) and a correction factor of 1.4 for differences in human and experimental exposure conditions: workers (5 working days) vs. general population (7 days continuous exposure) have been used.

Please also refer to argumentation stated below.

AF for dose response relationship:

1

Justification:

default

AF for differences in duration of exposure:

1

Justification:

no Assessment factor for differences in duration of exposure needs to be applied, as the AI applies to an oral chronic lifetime intake

AF for interspecies differences (allometric scaling):

1

Justification:

No allometric scaling should be applied in case of oral-to-inhalation extrapolation

AF for other interspecies differences:

1

Justification:

no Assessment factor for other interspecies differences needs to be applied, as the AI is a human derived value and is applicable for all adult human subjects and is also considered safe regarding reproduction and pre-perinatal development as well

AF for intraspecies differences:

1

Justification:

no Assessment factor for intraspecies differences needs to be applied, as the AI is applicable for all adult human subjects and is also considered safe regarding reproduction and pre-perinatal development as well

AF for the quality of the whole database:

1

Justification:

default (database is of high quality)

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:

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:

46.69 mg/kg bw/day

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

1

Dose descriptor starting point:

other: AI

Value:

6.67 mg/kg bw/day

Modified dose descriptor starting point:

other: corr. AI

Value:

46.69 mg/kg bw/day

Explanation for the modification of the dose descriptor starting point:

The Adequate Intake (AI) of 6.67 mg/kg bw/day corresponding to 46.69 mg/kg bw/day derived from the EFSA Panel on Dietetic Products, Nutrition and allergies (NDA, 2016; doi: 10.2903/j.efsa.2016.4484) for Choline is considered as the most conservative dose descriptor for the DNEL derivation.

 

Derivation of corrected AI: 6.67 mg/kg bw/day * (50 % / 10 %) * (7 d / 5 d) = 46.69 mg/kg bw/day

In detail, an oral absorption of 50 % and a dermal absorption of 10 % and a correction factor of 1.4 for differences in human and experimental exposure conditions: workers (5 working days) vs. general population (7 days continuous exposure) have been used.

 

Please also refer to argumentation stated below.

AF for dose response relationship:

1

Justification:

default

AF for differences in duration of exposure:

1

Justification:

no Assessment factor for differences in duration of exposure needs to be applied, as the AI applies to an oral chronic lifetime intake

AF for interspecies differences (allometric scaling):

1

Justification:

no Assessment factor for interspecies differences needs to be applied, as the AI is already a human derived value

AF for other interspecies differences:

1

Justification:

no Assessment factor for other interspecies differences needs to be applied, as the AI is a human derived value and is applicable for all adult human subjects and is also considered safe regarding reproduction and pre-perinatal development as well

AF for intraspecies differences:

1

Justification:

no Assessment factor for intraspecies differences needs to be applied, as the AI is applicable for all adult human subjects and is also considered safe regarding reproduction and pre-perinatal development as well

AF for the quality of the whole database:

1

Justification:

default (database is of high quality)

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:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

Workers - Hazard for the eyes

Local effects

Hazard assessment conclusion:

no hazard identified

Additional information - workers

The calculation of the DNELs is in general performed in accordance with the principles given in ECHA (2012) “Guidance of Information Requirements and Chemical Safety Assessment, Chapter R.8: Characterisation of dose [concentration]-response for human health.”

 

Available dose descriptors:

For Choline chloride (CAS 67-48-1), the following dose descriptors are available:

 

Hazard via inhalation route

Long-term exposure – systemic effects:

No route specific data is available. However, such studies are not considered necessary, due to exposure or other considerations regarding the unlikeliness of absorption as the oral route is considered to be the most likely one for humans, because the test substance has a very low vapour pressure and a high melting point, so the potential for the generation of inhalable forms is low. Furthermore, the substance is distributed as an aqueous solution, so no dust with inhalable particles will be formed and therefore no acute inhalation test was performed.

There is a chronic oral rat study available (Shivapurkar N, 1986) in which a NOAEL > 1200 mg/kg bw is reported (highest /only dose tested). In this study male Fischer 344 rats were exposed for 72 weeks + 31 weeks post-observation) orally via feed to choline chloride. The study was conducted similar to OECD guideline 452. Furthermore, there is a subchronic (3 – 4 months) study (Hodge, 1945), in which male and female rats were exposed orally via feed and drinking water (similar to OECD Guideline 408). A NOAEL of 1300 – 2900 mg/kg bw/day and a LOAEL of 3400 – 5000 mg/kg bw/day were reported. Moreover, a subacute (28 day) study is available (Mehta et al., 2009), in which male and female mice (Balb/c) were exposed to choline chloride either orally via gavage, intraperitoneally and intranasaly (GLP, OECD guideline 407 / no guideline available). Here a NOEL > 200 mg/kg bw/day (highest / only dose tested) was reported. All available studies revealed equivalent, plausible and consistent results over all three durations including a nearly lifetime exposure with an NOAEL > 1200 mg/kg bw., i.e. all studies give no rise to concern of compound-related toxic effects when applying Choline chloride repeatedly and trigger no classification as STOT-RE.

However, the (oral) Adequate Intake (AI) derived from the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA, 2016; doi: 10.2903/j.efsa.2016.4484) for Choline is considered as the most conservative dose descriptor for the DNEL derivation for the following reasons:

The AI of 400 mg/day, equivalent to an intake of 6.67 mg/kg bw/day, for adults is considered the recommended average daily intake which is assumed to be adequate for lifetime exposure of adult human subjects. Moreover, as even higher AI of 480 and 520 mg/day were set for pregnant and lactating women, respectively, the AI of 400 mg/day is considered safe regarding reproduction and pre-/perinatal development as well. Furthermore, it should be noted that the AI of 400 mg/day has been set based on the average observed choline intake in healthy populations in the European Union and in consideration of the amounts of choline needed to replete about 70 % of depleted subjects who showed signs of organ dysfunction in a depletion/repletion study. Thus, the DNELs derived from this AI should be considered as very conservative and highly protective. This is clearly supported by a chronic toxicity study on choline chlorine in rats, showing no signs for adverse effects in the observed endpoints even at a considerably high dose level yielding a NOAEL of > 1,200 mg/kg bw/day.

The AI is then converted into a corrected AI by route-to-route extrapolation as described in ECHA (2012) “Guidance of Information Requirements and Chemical Safety Assessment, Chapter R.8: Characterisation of dose [concentration]-response for human health.”

 

Acute short-term exposure – systemic effects:

Chapter 8.7.3 of the REACH TGD (R.8) indicates that acute exposure DNEL values are not normally required. It is specified: "For some toxic substances, for which there may be peak exposures, a DNELacute needs to be set and assessed in relation to the human peak exposure levels". This would be the case for substances with classification & labelling for acute hazards.

However, for Choline Chloride, according to ECHA's Guidance Part E (v3, May 2016) the hazard Assessment Conclusion "No hazard is identified” has been derived, as it is not classified for acute systemic hazards via all routes of exposure and has additionally a very low volatility with a vapor pressure of only 6.57*E-8 Pa at 25 °C (calculated value for the pure substance using EPIWINMPBPWIN v 1.44) or 2287.2 Pa at 25 °C (calculated value for a 75 % aqueous solution using EPIWIN MPBPWIN v1.44 and Raoult's law).

Therefore, Choline Chloride does not pose an inhalation hazard and inhalation is not a likely route of exposure. Therefore, no DNEL is required and a DNEL is not quantifiable and not relevant (No adequate route-specific information). Local effects can be covered sufficiently by the long-term DNEL for systemic effects.

 

Long-term exposure - local effects

Chapter 8.7.3 of the REACH TGD (R.8) indicates that acute and long-term local DNEL values are required for substances causing irritation, corrosion and/or sensitisation, assuming that the data allow setting a DNEL.

Choline Chloride has been found to be not irritating to the skin or the eyes. No data is available for the inhalatory route of exposure, but Choline Chloride is also not expected to be irritating to the respiratory system.

Therefore, neither a DNEL for short-term nor long-term inhalation for local effects is quantifiable (No adequate route-specific information) and the hazard assessment conclusion "no hazard identified" is chosen according to ECHA's Guidance Part E (v3,May 2016).

 

Acute short-term exposure – local effects

Chapter 8.7.3 of the REACH TGD (R.8) indicates that acute and long-term local DNEL values are required for substances causing irritation, corrosion and/or sensitisation, assuming that the data allow setting a DNEL.

Choline Chloride has been found to be not irritating to the skin or the eyes. No data is available for the inhalatory route of exposure, but Choline Chloride is also not expected to be irritating to the respiratory system.

Therefore, neither a DNEL for short-term nor long-term inhalation for local effects is quantifiable (No adequate route-specific information) and the hazard assessment conclusion "no hazard identified" is chosen according to ECHA's Guidance Part E (v3, May 2016).

 

Hazard via dermal route

Long-term exposure – systemic effects:

A repeated dose toxicity testing via dermal route was not performed (no route-specific data available), because the oral route is the most likely route of exposure for humans, the dermal route is not required and omitted due to animal welfare. Furthermore, although skin contact may possibly occur when using Choline chloride, the physico-chemical and toxicological properties do not suggest potential for a significant rate of absorption through the skin.

There is a chronic oral rat study available (Shivapurkar N, 1986) in which a NOAEL > 1200 mg/kg bw is reported (highest /only dose tested). In this study male Fischer 344 rats were exposed for 72 weeks + 31 weeks post-observation) orally via feed to choline chloride. The study was conducted similar to OECD guideline 452. Furthermore, there is a subchronic (3 – 4 months) study (Hodge, 1945), in which male and female rats were exposed orally via feed and drinking water (similar to OECD Guideline 408). A NOAEL of 1300 – 2900 mg/kg bw/day and a LOAEL of 3400 – 5000 mg/kg bw/day were reported. Moreover, a subacute (28 day) study is available (Mehta et al., 2009), in which male and female mice (Balb/c) were exposed to choline chloride either orally via gavage, intraperitoneally and intranasaly (GLP, OECD guideline 407 / no guideline available). Here a NOEL > 200 mg/kg bw/day (highest / only dose tested) was reported.All available studies revealed equivalent, plausible and consistent results over all three durations including a nearly lifetime exposure with an NOAEL > 1200 mg/kg bw., i.e. all studies give no rise to concern of compound-related toxic effects when applying Choline chloride repeatedly and trigger no classification as STOT-RE.

However, the (oral) Adequate Intake (AI) derived from the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA, 2016; doi: 10.2903/j.efsa.2016.4484) for Choline is considered as the most conservative dose descriptor for the DNEL derivation for the following reasons:

The AI of 400 mg/day, equivalent to an intake of 6.67 mg/kg bw/day, for adults is considered the recommended average daily intake which is assumed to be adequate for lifetime exposure of adult human subjects. Moreover, as even higher AI of 480 and 520 mg/day were set for pregnant and lactating women, respectively, the AI of 400 mg/day is considered safe regarding reproduction and pre-/perinatal development as well. Furthermore, it should be noted that the AI of 400 mg/day has been set based on the average observed choline intake in healthy populations in the European Union and in consideration of the amounts of choline needed to replete about 70 % of depleted subjects who showed signs of organ dysfunction in a depletion/repletion study. Thus, the DNELs derived from this AI should be considered as very conservative and highly protective. This is clearly supported by a chronic toxicity study on choline chlorine in rats, showing no signs for adverse effects in the observed endpoints even at a considerably high dose level yielding a NOAEL of > 1,200 mg/kg bw/day.

The AI is then converted into a corrected AI by route-to-route extrapolation as described in ECHA (2012) “Guidance of Information Requirements and Chemical Safety Assessment, Chapter R.8: Characterisation of dose [concentration]-response for human health.”

 

Acute short-term exposure – systemic effects:

Chapter 8.7.3 of the REACH TGD (R.8) indicates that acute exposure DNEL values are not normally required. It is specified: "For some toxic substances, for which there may be peak exposures, a DNELacute needs to be set and assessed in relation to the human peak exposure levels". This would be the case for substances with classification & labelling for acute hazards.

However, for Choline Chloride, according to ECHA's Guidance Part E (v3, May 2016) the hazard Assessment Conclusion "No hazard is identified” has been derived, as it is not classified for acute systemic hazards via all routes of exposure.

Therefore, Choline Chloride does not pose a dermal hazard. Therefore, no DNEL is required and a DNEL is not quantifiable and not relevant (No adequate route-specific information). Local effects can be covered sufficiently by the long-term DNEL for systemic effects.

 

Long-term exposure - local effects

Chapter 8.7.3 of the REACH TGD (R.8) indicates that acute and long-term local DNEL values are required for substances causing irritation, corrosion and/or sensitisation, assuming that the data allow setting a DNEL.

Choline Chloride has been found to be not irritating to the skin or the eyes.

Therefore, neither a DNEL for short-term nor long-term dermal for local effects is quantifiable (No adequate route-specific information) and the hazard assessment conclusion "no hazard identified" is chosen according to ECHA's Guidance Part E (v3, May 2016).

 

Acute short-term exposure – local effects:

Chapter 8.7.3 of the REACH TGD (R.8) indicates that acute and long-term local DNEL values are required for substances causing irritation, corrosion and/or sensitisation, assuming that the data allow setting a DNEL.

Choline Chloride has been found to be not irritating to the skin or the eyes.

Therefore, neither a DNEL for short-term nor long-term dermal for local effects is quantifiable (No adequate route-specific information) and the hazard assessment conclusion "no hazard identified" is chosen according to ECHA's Guidance Part E (v3, May 2016).

 

Modification of the starting point:

From all available data for the different human health endpoints it is clear that choline chloride (CAS 67-48-1) exerts its effects by a threshold mode of action. Thus, DNELs can be calculated for the different threshold endpoints based on the most relevant dose descriptors per endpoint. DNELs are derived based on the available toxicity data for the target substance reflecting the routes, the duration and the frequency of exposure.

 

Bioavailability (absorption)

There is no substance-specific information on absorption by the oral, dermal and inhalation routes available for choline chloride (CAS 67-48-1). The absorption rates are assessed based on the physico-chemical properties of the substance.

No data needed to be derived for dermal exposure, because the physicochemical and toxicological properties do not suggest a potential for a significant rate of absorption through the skin. Due to the high water solubility of the substance (≥ 79.3 g/100 g and < 89.7 g/100 g (m test item / m mixture) at T = 23 °C and at T = 20 °C ± 0.5 °C.), its log Kow of -3.77 and molecular weight of 139.6238 g/mol, dermal absorption is expected to a minor extent. As such, taking into account the negligible ability of Choline chloride to penetrate the stratum corneum, an absorption rate of 10 % after dermal exposure needs to be considered for DNEL derivation.

Also, no data is needed for the application of Choline chloride via inhalation, because Choline chloride has a very low vapor pressure and a high melting point, so the potential for the generation of inhalable forms is low and no dust with inhalable particles will be formed. As such, taking into account the limited absorption due to the ionic structure, and the poorer expression of specific transport mechanisms, an absorption rate of 25 % after inhalation exposure needs to be considered for DNEL derivation.

In addition, taking into account the ionic structure, specific transport mechanisms and partial metabolism of the compound by the intestinal microflora, an absorption rate of 50 % after oral exposure is considered appropriate.

 

Route-to-route extrapolation:

Oral-to-inhalation extrapolation is performed to obtain a long-term inhalation AI for systemic effects from the oral human AI from the Scientific opinion "Dietary Reference Values for choline" (NDA, 2016; doi: 10.2903/j.efsa.2016.4484). According to "Guidance of Information Requirements and Chemical Safety Assessment, Chapter R.8, in case of oral-to-inhalation extrapolation a default factor of 2 for absorption should be introduced.

The following formula was used: corrected inhalative AI = oral AI x (1/sRVhuman) x (ABSoral-human) x (ABSinhalation-human) x (6.7 m³/ 10 m³) x /7/5);

where sRV is standard respiratory volume of humans during 8 hours (= 0.096 m³/kg/day); ABS-absorption and 6.7 m³ and 10 m³ are standard respiratory volumes for workers under normal conditions and by light activity, and 7d/5d is the different exposure duration in humans (general population) and human workers - workers (5 working days) vs. general population (7 days continuous exposure)

 

Oral-to-dermal extrapolation is performed to obtain long-term dermal AI for systemic effects from the oral human AI from the Scientific opinion "Dietary Reference Values for choline" (NDA, 2016; doi: 10.2903/j.efsa.2016.4484). The following formula was used:

corrected dermal AI = oral AI * (ABS oral-human/ABS dermal-human), * 7d/5d;

where ABS is absorption, and 7d/5d is the different exposure duration in humans (general population) and human workers - workers (5 working days) vs. general population (7 days continuous exposure)

 

Exposure conditions and respiratory volumes:

Differences in the respiratory volumes between experimental animals and humans were used when an oral human AI from the Scientific opinion "Dietary Reference Values for choline" (NDA, 2016; doi: 10.2903/j.efsa.2016.4484) was used to assess inhalation exposure in humans. 0.096 m³/kg/day is the standard respiratory volumes in humans during 8h exposure. 6.7 and 10 m³ (each referring to a duration of 8 hours) are standard respiratory volumes for workers under normal conditions and by light activity, respectively. Furthermore, the different exposure condition in human workers and general population was taken into account (workers - 5 working days - versus - general population - 7 days continuous exposure).

 

Applying of assessment factors and calculation of DNELs:

No assessment factors have been applied to the corrected AI to obtain the endpoint specific DNELs. As this value applies for humans - including vulnerable population groups such as pregnant women - and for a life-time exposure duration, no Assessment factors (AFs) to correct uncertainties and variability within and between species in the effect data are necessary.

 

Calculation of DNELs:

Long-term exposure by inhalation – systemic effects:

The oral human AI of 6.67 mg/kg bw was converted into the inhalation AI:

Modification of the starting point: corrected NOAEC = 6.67 mg/kg bw x (1/0.096 m³) *(6.7/10)m³ * (50 % / 25 %) * (7 d/ 5 d) = 194.54 mg/m³.

Derivation of DNEL = corr. AI = 194.54 mg / m³

(No Assessment factors)

 

Long-term dermal exposure – systemic effects:

The oral human AI of 6.67 mg/kg bw was converted into the dermal AI:

corrected dermal AI = 6.67 x (ABS oral-humanABS dermal-human) x (exposure of animals per week)

correc. dermal AI = 46.69 mg/kg bw

DNEL: corr. AI = 46.69 mg / kg bw/days

(No Assessment factors)

 

 

Justification for DNEL Derivation:

As outlined above, DNELs were derived using the Adequate Intake (AI) for non-pregnant adults (400 mg/day) published by EFSA Panel on Dietetic Products, Nutrition and Allergies (2016, doi: 10.2903/j.efsa.2016.4484). This recommended average daily intake level corresponds to 6.7 mg/kg/day, based on an adequate intake of 400 mg/kg and a reference body weight of 60 kg and is considered adequate for lifetime exposure of adult human subjects.

Moreover, as even higher AI of 480 and 520 mg/day were set for pregnant and lactating women, respectively, the AI of 400 mg/day is considered safe regarding reproduction and pre-/perinatal development as well. Furthermore, it should be noted that the AI of 400 mg/day has been set based on the average observed choline intake in healthy populations in the European Union and in consideration of the amounts of choline needed to replete about 70 % of depleted subjects who showed signs of organ dysfunction in a depletion/repletion study. Thus, the DNELs derived from this AI should be considered as very conservative and highly protective.

 

In the following, for the purpose of comparability the DNELs derived using the standard approach as explained in the respective guidance documents are given.

The DNEL calculation based on a NOAEL of a chronic oral feeding study in rats (Shivapurka et al., 1986) is shown under point 1. Under point 2, the DNEL calculation based on the value of upper limit of choline for human adults, which correlates with hypotensive effect, nausea and diarrhoea, is shown.

 

As demonstrated in the summary table under point 3, the standard DNEL calculations using descriptors based on adversity observed in animal or human studies lead to significantly higher limit values than the DNEL calculation using the EFSA AI for choline.

 

Following the precautionary principle the EFSA AI for choline is considered as the most critical value resulting in the most conservative dose descriptor for DNEL derivation.

 

1.      NOAEL/NOEL from chronic animal study (rats, oral, feed) (Shivapurka et al, 1986):

No systemic effects, treatment for 72 weeks, observation 31 weeks: NOAEL = NOEL: >1200 mg/kg bw/d

 

- DNEL systemic, worker inhalation (long term):
Corrected NOAEL: 1200 mg/kg bw x (1/0.38 m³/kg/day) x (50 %/25 %) x (6.7/10) = 4231.58 mg/m³
Applied AFs: DNEL = 4231.58 mg/m³/(2.5 x 5 x 1 x 1 x 1 x 1) = 338.5 mg/m³

 

- DNEL systemic, worker dermal (long term):
Corrected NOAEL: 1200 mg/kg bw x (50 %/10 %) = 6000 mg/kg bw
Applied AF: DNEL = 6000 mg/kg bw/(4 x 2.5 x 5 x 1 x 1 x 1) = 120 mg/kg bw.

 

2.      Upper limit -> 3.5 g choline/d for adults (50 mg/kg bw/d) (EFSA, 2016)

LOAEL 7.5 g/d of choline for adults (70 kg) (US Institute of Medicine, 1998): correlated with hypotensive effect, nausea and diarrhoea; Uncertainty factor 2: Upper limit -> 3.5 g choline/d for adults (50 mg/kg bw/d)

 

- DNEL systemic, worker inhalation (long term): 50 mg/kg bw/day * (1/0.096 m³ / kg bw/day) * (6.7 m³ / 10 m³) * (50 % /25 %) * (7 d/ 5d) = 977 mg/m³

- DNEL systemic, worker dermal (long term): 50 mg/kg bw/day * (50 % / 10 %) * (7 d / 5 d) = 350 mg/kg bw/day

 

3.      Summary

Systemic DNELs	Rodent data	AI	UL
worker inhalation	338.5 mg/m³	194.54 mg/m³	977 mg/m³
worker dermal	120 mg/kg bw/day	46.69 mg/kg bw/day	350 mg/kg bw/day

 

Based on these calculations, it is clear that the EFSA approach based on the AI reveals the lowest value. This value was chosen in a worst-case-approach as it represents the most conservative approach for DNEL derivation.

General Population - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

46.64 mg/m³

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

1

Dose descriptor starting point:

other: AI

Value:

6.67 mg/kg bw/day

Modified dose descriptor starting point:

other: corr. AI

Value:

46.64 mg/m³

Explanation for the modification of the dose descriptor starting point:

The Adequate Intake (AI) of 6.67 mg/kg bw/day corresponding to 46.64 mg/m³ derived from the EFSA Panel on Dietetic Products, Nutrition and allergies (NDA, 2016; doi: 10.2903/j.efsa.2016.4484) for Choline is considered as the most conservative dose descriptor for the DNEL derivation.

 

Details on derivation of corrected AI: 6.67 mg/kg bw/day * (1/0.286 m³ / mg/kg bw/day) * (50 % / 25 %) = 46.64 mg/m³

(the standard respiratory volume of humans during 24 hours of 0.286 m³/kg/day has been used.

 

Please also refer to argumentation stated below.

AF for dose response relationship:

1

Justification:

default

AF for differences in duration of exposure:

1

Justification:

no Assessment factor for differences in duration of exposure needs to be applied, as the AI applies to an oral chronic lifetime intake

AF for interspecies differences (allometric scaling):

1

Justification:

No allometric scaling should be applied in case of oral-to-inhalation extrapolation

AF for other interspecies differences:

1

Justification:

no Assessment factor for other interspecies differences needs to be applied, as the AI is a human derived value and is applicable for all adult human subjects and is also considered safe regarding reproduction and pre-perinatal development as well

AF for intraspecies differences:

1

Justification:

no Assessment factor for intraspecies differences needs to be applied, as the AI is applicable for all adult human subjects and is also considered safe regarding reproduction and pre-perinatal development as well

AF for the quality of the whole database:

1

Justification:

default (database is of high quality)

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:

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:

33.35 mg/kg bw/day

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

1

Dose descriptor starting point:

other: AI

Value:

6.67 mg/kg bw/day

Modified dose descriptor starting point:

other: corr. AI

Value:

33.35 mg/kg bw/day

Explanation for the modification of the dose descriptor starting point:

The Adequate Intake (AI) of 6.67 mg/kg bw/day corresponding to 33.35 mg/kg bw/day derived from the EFSA Panel on Dietetic Products, Nutrition and allergies (NDA, 2016; doi: 10.2903/j.efsa.2016.4484) for Choline is considered as the most conservative dose descriptor for the DNEL derivation.

 

Derivation of corrected AI: 6.67 mg/kg bw/day * (50 % / 10 %) = 33.35 mg/kg bw/day

In detail, an oral absorption of 50 % and a dermal absorption of 10 % has been used.

 

Please also refer to argumentation stated below.

AF for dose response relationship:

1

Justification:

default

AF for differences in duration of exposure:

1

Justification:

no Assessment factor for differences in duration of exposure needs to be applied, as the AI applies to an oral chronic lifetime intake

AF for interspecies differences (allometric scaling):

1

Justification:

no Assessment factor for interspecies differences needs to be applied, as the AI is already a human derived value

AF for other interspecies differences:

1

Justification:

no Assessment factor for other interspecies differences needs to be applied, as the AI is a human derived value and is applicable for all adult human subjects and is also considered safe regarding reproduction and pre-perinatal development as well

AF for intraspecies differences:

1

Justification:

no Assessment factor for intraspecies differences needs to be applied, as the AI is applicable for all adult human subjects and is also considered safe regarding reproduction and pre-perinatal development as well

AF for the quality of the whole database:

1

Justification:

default (database is of high quality)

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:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

General Population - Hazard via oral route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

6.67 mg/kg bw/day

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

1

Dose descriptor starting point:

other: AI

Value:

6.67 mg/kg bw/day

Modified dose descriptor starting point:

other: corr. AI

Value:

6.67 mg/kg bw/day

Explanation for the modification of the dose descriptor starting point:

The Adequate Intake (AI) of 6.67 mg/kg bw/day derived from the EFSA Panel on Dietetic Products, Nutrition and allergies (NDA, 2016; doi: 10.2903/j.efsa.2016.4484) for Choline is considered as the most conservative dose descriptor for the DNEL derivation.

 

Derivation of corrected AI: 6.67 mg/kg bw/day = 6.67 mg/kg bw/day (no correction necessary)

 

Please also refer to the argumentation stated below.

AF for dose response relationship:

1

Justification:

default

AF for differences in duration of exposure:

1

Justification:

no Assessment factor for differences in duration of exposure needs to be applied, as the AI applies to an oral chronic lifetime intake

AF for interspecies differences (allometric scaling):

1

Justification:

no Assessment factor for interspecies differences needs to be applied, as the AI is already a human derived value

AF for other interspecies differences:

1

Justification:

no Assessment factor for other interspecies differences needs to be applied, as the AI is a human derived value and is applicable for all adult human subjects and is also considered safe regarding reproduction and pre-perinatal development as well

AF for intraspecies differences:

1

Justification:

no Assessment factor for intraspecies differences needs to be applied, as the AI is applicable for all adult human subjects and is also considered safe regarding reproduction and pre-perinatal development as well

AF for the quality of the whole database:

1

Justification:

default (database is of high quality)

AF for remaining uncertainties:

1

Justification:

no remaining uncertainties

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

General Population - Hazard for the eyes

Local effects

Hazard assessment conclusion:

no hazard identified

Additional information - General Population

The principles of the DNEL calculation for the general population are the same as already described for workers. However, there are additional considerations or deviations for:

 

Modification of the starting point:

 

Bioavailability (absorption):

The oral, dermal and inhalation absorption values used are the same as done for workers.

 

Respiratory volumes:

Adaptions in the respiratory volumes under normal conditions in humans were taken into account. A default respiratory volume of 0.286 m³/kg bw for humans (general population) was used to convert oral AI into inhalation AI, referring to 24h exposure instead of 8h (worker).

Additional explanation: the sRV (standard respiratory volume of humans during 24 hours) of 0.286 m³/kg/day has been used.

 

Applying of assessment factors:

No assessment factors have been applied to the corrected AI to obtain the endpoint specific DNELs. As this value applies for humans - including vulnerable population groups such as pregnant women - and for a life-time exposure duration, no Assessment factors (AFs) to correct uncertainties and variability within and between species in the effect data are necessary.

 

Calculation of endpoint-specific DNELs for general population

Long-term exposure - systemic effects (oral):

The oral AI of 6.67 mg/kg bw was not modified for differences in absorption by oral route since no substance- and route specific information is available:

DNEL = 6.67 mg/kg bw/day = 6.67 mg/kg bw.

(No Assessment factors).

 

Long-term exposure - systemic effects (dermal):

For the oral AI of 6.67 mg/kg bw, the following conversion was necessary:

dermal AI = oral AI x (50 % / 10 %) = 33.35 mg/kg bw

(an oral absorption of 50 % and a dermal absorption of 10 %)

DNEL = 33.35 mg/kg bw = 33.35 mg/kg bw.

(No Assessment factors)

 

Long-term exposure - systemic effects (inhalation):

The oral AI of 6.67 mg/kg bw was converted into the inhalation AI:

Corrected inhalation AI = oral AI x (1/0.286 m³/kg bw/day) x (ABS oral-humanABS inhal-human), where 0.286 is the standard respiratory volume (m³/kg bw) of humans during 24 h exposure, ABS is absorption (values are the same as described for workers).

Corrected Inhalation AI = 6.67 mg/kg bw x (1/0.286 m³/kg/day) x (50 %/25 %) = 46.64 mg/m³

DNEL = 46.64 mg/m³ = 46.64 mg/m³.

(No Assessment factors)

 

Selected DNELs

DNEL systemic oral = 6.67 mg/kg bw

DNEL systemic dermal = 33.35 mg/kg bw

DNEL systemic inhalation = 46.64 mg/m³

 

Justification for DNEL Derivation:

As outlined above, DNELs were derived using the Adequate Intake (AI) for non-pregnant adults (400 mg/day) published by EFSA Panel on Dietetic Products, Nutrition and Allergies (2016, doi: 10.2903/j.efsa.2016.4484).

This recommended average daily intake level corresponds to 6.67 mg/kg/day, based on an adequate intake of 400 mg/day and a reference body weight of 60 kg and is considered adequate for lifetime exposure of adult human subjects.

Moreover, as even higher AI of 480 and 520 mg/day were set for pregnant and lactating women, respectively, the AI of 400 mg/day is considered safe regarding reproduction and pre-/perinatal development as well. Furthermore, it should be noted that the AI of 400 mg/day has been set based on the average observed choline intake in healthy populations in the European Union and in consideration of the amounts of choline needed to replete about 70 % of depleted subjects who showed signs of organ dysfunction in a depletion/repletion study. Thus, the DNELs derived from this AI should be considered as very conservative and highly protective.

 

In the following, for the purpose of comparability the DNELs derived using the standard approach as explained in the respective guidance documents are given.

The DNEL calculation based on a NOAEL of a chronic oral feeding study in rats (Shivapurka et al., 1986) is shown under point 1. Under point 2, the DNEL calculation based on the value of the upper limit (UL) of choline for human adults, which correlates with hypotensive effect, nausea and diarrhoea, is shown.

 

As demonstrated in the summary table under point 3, the standard DNEL calculations using descriptors based on adversity observed in animal or humans studies lead to significantly higher limit values than the DNEL calculation using the EFSA AI for choline.

Following the precautionary principle, the EFSA AI for choline is considered as the most critical value resulting in the most conservative dose descriptor for DNEL derivation.

 

1.      NOAEL/NOEL from chronic animal study (rats, oral, feed) (Shivapurka et al, 1986):

No systemic effects, treatment for 72 weeks, observation 31 weeks: NOAEL = NOEL: >1200 mg/kg bw/d

 

- DNEL systemic, general population inhalation (long term):
Corrected NOAEL: 1200 mg/kg bw x (1/1,15 m³/kg/day) x (50 %/25 %) = 2086.96 mg/m³
Applied AFs: DNEL = 2086.96 mg/m³ / (2.5 x 10 x 1 x 1 x 1 x 1) = 83.48 mg/m³.

 

- DNEL systemic, general population dermal (long term):
Corrected NOAEL: 1200 mg/kg bw x (50 %/10 %) = 6000 mg/kg bw
Applied AF: DNEL = 6000 mg/kg bw/(4 x 2.5 x 10 x 1 x 1 x 1) = 60 mg/kg bw/d

 

- DNEL systemic, general population oral = 1200 mg/kg bw / (4 x 2.5 x 10 x 1 x 1 x 1) = 12 mg/kg bw

 

2.      Upper limit -> 3.5 g choline/d for adults (50 mg/kg bw/d) (EFSA, 2016)

LOAEL 7.5 g/d of choline for adults (70 kg) (US Institute of Medicine, 1998): correlated with hypotensive effect, nausea and diarrhoea; Uncertainty factor 2: Upper limit -> 3.5 g choline/d for adults (50 mg/kg bw/d)

 

- DNEL systemic, general population inhalation (long term): 50 mg/kg bw/day * (1/0.286 m³ / mg/kg bw/day) * (50 % / 25 %) = 350 mg/m³

- DNEL systemic, general population dermal (long term): 50 mg/kg bw/day * (50 % / 10 %) = 250 mg/kg bw/day

- General population oral (long term): 50 mg/kg bw/d

 

3.      Summary

Systemic DNELs	Rodent data	AI	UL
General population, inhalation	83.48 mg/m³	46.64 mg/m³	350 mg/m³
General population, dermal	60 mg/kg bw	33.35 mg/kg bw/day	250 mg/kg bw/day
General population, oral	12 mg/kg bw/day	6.67 mg/kg bw	50 mg/kg bw/day

 

Based on these calculations, it is clear that the EFSA approach based on the AI reveals the lowest value. This value was chosen in a worst-case-approach as it represents the most conservative approach for DNEL derivation.