Alkyl Ester Quaternary Ammonium Compounds Lack Skin-Sensitizing Potential

Table 1. Summary of Human Data for HEQ and TEA-Quat
Human Maximization Test	TEA-Quat		HEQ
Number of allergic skin reactions at challenge 1	0/25		0/25
Number of allergic skin reactions at challenge 2	0/3		0/3
Diagnostic Patch Test	Irritant	Allergic	Irritant	Allergic
Number of skin reactions to 2% concentration at 2-day scoring*	0/183	0/183	0/183	0/183
Number of skin reactions to 5% concentration at 2-day scoring^†	16/239	0/239	1/239	0/239

HEQ = di-(hardened tallow fatty acid) ester of 2,3-dihydroxypropyl-trimethyl ammonium chloride; TEA-Quat = dialkyl ester of triethanol ammonium methyl sulfate.
*Only the 183 patients examined at St. John's Institute of Dermatology (London, UK) were assessed with the test materials at 2%.
^†The 183 patients examined at St. John's Institute of Dermatology (London, UK) and the 56 patients examined at the Contact Dermatitis Clinic at K.U. Leuven University Hospital (Leuven, Belgium) were assessed with the test materials at 5% (total = 239).

Table 1. Summary of Human Data for HEQ and TEA-Quat
Human Maximization Test	TEA-Quat		HEQ
Number of allergic skin reactions at challenge 1	0/25		0/25
Number of allergic skin reactions at challenge 2	0/3		0/3
Diagnostic Patch Test	Irritant	Allergic	Irritant	Allergic
Number of skin reactions to 2% concentration at 2-day scoring*	0/183	0/183	0/183	0/183
Number of skin reactions to 5% concentration at 2-day scoring^†	16/239	0/239	1/239	0/239

HEQ = di-(hardened tallow fatty acid) ester of 2,3-dihydroxypropyl-trimethyl ammonium chloride; TEA-Quat = dialkyl ester of triethanol ammonium methyl sulfate.
*Only the 183 patients examined at St. John's Institute of Dermatology (London, UK) were assessed with the test materials at 2%.
^†The 183 patients examined at St. John's Institute of Dermatology (London, UK) and the 56 patients examined at the Contact Dermatitis Clinic at K.U. Leuven University Hospital (Leuven, Belgium) were assessed with the test materials at 5% (total = 239).

Table 2. Formulas and Values Used to Generate a Quantitative Risk Assessment for the Use of HEQ at 15% in a Fabric Rinse Conditioner
Acceptable Exposure Level Calculations
Formula Used		Description
AEL = NESIL/SAFt		Calculate the acceptable exposure level (AEL) in µg/cm².
NESIL = (M1/SA) x F0 x F-3		Calculate the no-expected-sensitization induction level (NESIL) in µg/cm², based on the concentration of material tested in the human maximization test.
SA = Π x r2		Calculate the surface area (SA) of skin (in cm²) exposed in the human maximization test.
SAFt = SAFi x SAFm x SAFe		Calculate the product of the three sensitization assessment factors (SAFs).
Dermal Exposure Level Calculations*
Formula Used		Description
EXPFABRIC = F1 x C' x F2 x F3		Calculate dermal exposure to HEQ from washed fabrics.
EXPHANDWASH = F1 x C-3		Calculate dermal exposure to HEQ during hand washing.
C' = (M2 x F' x FD)/W		Calculate product load (mg/cm²).
C-3 = C x Tder		Calculate product load (mg/cm²).
Parameters and Assigned Parameter Values*
Parameter	Description	Assigned Value	Reference
C	Concentration (mg/cm³) of fabric conditioner used for hand wash	1% = 10 mg/cm³	13
F'	Percentage weight fraction of HEQ deposited on fabric	5%	13
F-3	Percent weight fraction of material tested	15%	"Materials" and "Methods"
F0	Percent of HEQ in material tested	83%	"Materials" and "Methods"
F1	Percent weight fraction of HEQ in product	15%	(Typical level for fabric conditioner concentrate)
F2	Percent weight fraction transferred from fabric to skin	1%	13
F3	Percent weight fraction remaining on skin	100%	13
FD	Fabric density (mg/cm²)	20 mg/cm²	13
SAFi	Interindividual variability SAF	10	12
SAFm	Matrix variability SAF	1	12
SAFe	Exposure variability SAF	2	12
M1	Amount (g) of test material applied to chamber	0.2 g	"Materials" and "Methods"
M2	Amount (mg) of fabric conditioner used	90,000	13
Π	Constant	Π	-
r	Radius (cm) of Hilltop Chamber	1.25 cm	"Materials" and "Methods"
Tder	Thickness (cm) of product layer in contact with skin	0.01 cm	13
W	Mass (mg) of fabric washed	1,000,000 mg	13

AEL = acceptable exposure level; EXPFABRIC = exposure from clothing washed with fabric softeners; EXPHANDWASH = direct exposure during hand washing; HEQ = di-(hardened tallow fatty acid) ester of 2,3-dihydroxypropyl-trimethyl ammonium chloride; NESIL = no-expected-sensitization induction level; SA = surface area; SAF = sensitization assessment factor.
*From the Human and Environmental Risk Assessment technical guidance document for risk assessments relating to household cleaning products.^[13]

Table 2. Formulas and Values Used to Generate a Quantitative Risk Assessment for the Use of HEQ at 15% in a Fabric Rinse Conditioner
Acceptable Exposure Level Calculations
Formula Used		Description
AEL = NESIL/SAFt		Calculate the acceptable exposure level (AEL) in µg/cm².
NESIL = (M1/SA) x F0 x F-3		Calculate the no-expected-sensitization induction level (NESIL) in µg/cm², based on the concentration of material tested in the human maximization test.
SA = Π x r2		Calculate the surface area (SA) of skin (in cm²) exposed in the human maximization test.
SAFt = SAFi x SAFm x SAFe		Calculate the product of the three sensitization assessment factors (SAFs).
Dermal Exposure Level Calculations*
Formula Used		Description
EXPFABRIC = F1 x C' x F2 x F3		Calculate dermal exposure to HEQ from washed fabrics.
EXPHANDWASH = F1 x C-3		Calculate dermal exposure to HEQ during hand washing.
C' = (M2 x F' x FD)/W		Calculate product load (mg/cm²).
C-3 = C x Tder		Calculate product load (mg/cm²).
Parameters and Assigned Parameter Values*
Parameter	Description	Assigned Value	Reference
C	Concentration (mg/cm³) of fabric conditioner used for hand wash	1% = 10 mg/cm³	13
F'	Percentage weight fraction of HEQ deposited on fabric	5%	13
F-3	Percent weight fraction of material tested	15%	"Materials" and "Methods"
F0	Percent of HEQ in material tested	83%	"Materials" and "Methods"
F1	Percent weight fraction of HEQ in product	15%	(Typical level for fabric conditioner concentrate)
F2	Percent weight fraction transferred from fabric to skin	1%	13
F3	Percent weight fraction remaining on skin	100%	13
FD	Fabric density (mg/cm²)	20 mg/cm²	13
SAFi	Interindividual variability SAF	10	12
SAFm	Matrix variability SAF	1	12
SAFe	Exposure variability SAF	2	12
M1	Amount (g) of test material applied to chamber	0.2 g	"Materials" and "Methods"
M2	Amount (mg) of fabric conditioner used	90,000	13
Π	Constant	Π	-
r	Radius (cm) of Hilltop Chamber	1.25 cm	"Materials" and "Methods"
Tder	Thickness (cm) of product layer in contact with skin	0.01 cm	13
W	Mass (mg) of fabric washed	1,000,000 mg	13

AEL = acceptable exposure level; EXPFABRIC = exposure from clothing washed with fabric softeners; EXPHANDWASH = direct exposure during hand washing; HEQ = di-(hardened tallow fatty acid) ester of 2,3-dihydroxypropyl-trimethyl ammonium chloride; NESIL = no-expected-sensitization induction level; SA = surface area; SAF = sensitization assessment factor.
*From the Human and Environmental Risk Assessment technical guidance document for risk assessments relating to household cleaning products.^[13]

Evidence That Two Alkyl Ester Quaternary Ammonium Compounds Lack Substantial Human Skin-Sensitizing Potential

Calculation of NESIL

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Evidence That Two Alkyl Ester Quaternary Ammonium Compounds Lack Substantial Human Skin-Sensitizing Potential

Calculation of NESIL

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