ISO 23698:2024 化粧品 — 拡散反射分光法による日焼け止め効果の測定 | ページ 6

3.1.1

absorbance

A

measure of the energy blocked, either by optical absorption or by physical scattering/reflection

3.1.2

absorbance spectrum

A(λ)

sunscreen optical absorbance at wavelength λ

Note 1 to entry: Logarithm to the base 10 of the reciprocal of the spectral transmittance τ(λ). A(λ) = -[log₁₀ τ(λ)].

3.1.3

absorbance by diffuse reflectance spectroscopy

absorbance by DRS

A_DRS(λ)

absorbance spectrum calculated from DRS as a function of wavelength λ

Note 1 to entry: The absorbance spectrum relevant to this document is 320 nm to 400 nm.

3.1.4

absorbance after hybridization

A_HDRS(λ)

final absorbance spectrum calculated from the hybridized signals as a function of wavelength λ after correction for photo-degradation

Note 1 to entry: The final absorbance spectrum is 290 nm to 400 nm

3.1.5

calibration factor

C_cal

correction applied to a measured quantity value to compensate for a known systematic effect

3.1.6

in vitro UV absorbance spectrum pre irradiation

in vitro absorbance before UV exposure (pre irradiation)

A_vt0(λ)

arithmetic mean in vitro absorbance spectrum of a sunscreen product measured before UV exposure

Note 1 to entry: The absorbance spectrum is 290 nm to 400 nm.

3.1.7

in vitro UV absorbance spectrum post irradiation

in vitro absorbance after UV exposure (post irradiation)

A_vt1(λ)

arithmetic mean in vitro absorbance spectrum of a sunscreen product measured after UV exposure

Note 1 to entry: The absorbance spectrum is 290 nm to 400 nm.

3.1.8

hybridization constant

C_Ai

scalar factor to adjust an in vitro spectrum A_vt1 (λ) at each wavelength to the individual A_DRSi

3.1.9

critical wavelength

CW

λ_c

wavelength at which the area under the absorbance curve represents 90 % of the total area under the curve in the UV region

3.1.10

dose

D

UVA radiant exposure dose for pre-irradiation of sunscreen products (1,2 x UVA-PF_DRS J/cm²)

3.1.11

wavelength step

dλ

differential of integration (1 nm)

3.1.12

diffuse reflectance spectroscopy

DRS

technique used to measure the remitted light from skin or skin remittance.

Note 1 to entry: Using this technique, the UVA absorbance spectrum of a sunscreen product applied on skin in vivo can be determined.

Note 2 to entry: The term “light” is used generically to describe electromagnetic radiation from both UV and visible wavelengths of optical spectrum throughout the document. It is differentiated as needed in specific sections of the document.

Note 3 to entry: The UV energy that is measured is not energy reflected from the surface of the skin or the applied sunscreen. The UV energy being measured has passed through the sunscreen, entered the surface of the skin, and been scattered therein. Some of this energy is remitted back to the surface of the skin through the sunscreen a second time and picked up by the DRS optical probe. The term “remittance” is used throughout this document whereas historical use of the term “reflectance” has had precedence in published literature.

3.1.13

erythema action spectrum

E(λ)

relative effects of individual spectral bands of an exposure source causing an erythema response in skin

Note 1 to entry: See Annex E.

3.1.14

hybrid diffuse reflectance spectroscopy

HDRS

method to evaluate the protection provided by a sunscreen product applied on skin in vivo wherein the UVA Protection Factor is measured by DRS and the UVB part of the spectrum by in vitro thin film spectroscopy, and the two spectra are merged to form a hybrid absorbance spectrum

Note 1 to entry: The spectral distributions determined by the two different methods are merged to form the hybrid spectral absorption A_HDRS(λ).

3.1.15

hybridization wavelength

HW

λ_HW

wavelength at which the in vivo DRS spectrum and the in vitro absorbance spectrum are merged

3.1.16

PPD action spectrum

P(λ)

relative effects of individual spectral bands of an exposure source to cause persistent pigment darkening (PPD)

Note 1 to entry: See Annex E.

3.1.17

sun protection factor by hybrid DRS

SPF_HDRS

SPF of a sunscreen product calculated from hybridized UV absorbance spectrum adjusted by spectral ratio of photo-degradation (SRPD) (λ)

3.1.18

spectral ratio of photo-degradation (λ)

S_RPD(λ)

ratio of the in vitro absorbance spectra (post- and pre-irradiation) representing the photo-degradation of the sunscreen product as function of wavelength

Note 1 to entry: SRPD(λ) spectrum is 290 nm to 400 nm

3.1.19

subsite

area within a test site where the DRS probe is placed to take the individual skin remittance measurement denoted by index j

3.1.20

test site

defined area of the skin to which a test sunscreen material is applied and where DRS measurements are conducted

3.1.21

Student's t value

t

two tail Student’s t-test critical value for 0,05, with n-1 degrees of freedom

3.1.22

transmittance spectrum by DRS

T_DRS(λ)

in vivo transmittance spectrum of a sunscreen product calculated from DRS as a function of wavelength λ

Note 1 to entry: The in vivo transmittance spectrum is 320 nm to 400 nm.

3.1.23

UVA protection factor by DRS

UVA-PF_DRS

initial UVA protection factor of a sunscreen product calculated using the measured in vivo absorbance spectrum from DRS before correction for photo-degradation

3.1.24

UVA protection factor by HDRS

UVA-PF_HDRS

UVA protection factor of a sunscreen product calculated from hybridized UV absorbance spectrum adjusted by SRPD(λ)