Consumer exposure to oxidative hair dyes.
A [14C]-PPD labelled mass balance study.

Rationale: At present, despite the wide use of PPD, data on the extent of
systemic exposure of consumers to this active ingredient in hair dyes under
realistic use conditions is not available. Once knowledge on the extent of
systemic exposure under typical *in-use* conditions has been gained, the risk
for consumers using PPD-containing hair dye products can be assessed properly.
This study is set up:
- to gain realistic data and to get insight on the systemic exposure to PPD in
consumers (n=16), resulting from a single hair dye procedure performed by
professional hairdressers under realistic conditions;
- to establish a *mass balance*, since [14C]-radiolabelled PPD is used in this
study.

The primary study objective is to establish the systemic exposure of consumers
to PPD during a single typical hair dye procedure.

The systemic exposure derived from an oxidative hair dye procedure is evaluated
following a single controlled application performed by professional
hairdressers of a [14C]-labelled hair dye onto the hairy scalp of healthy
subjects. Plasma and urinary levels of [14C]-PPD will give insight into the
extent of systemic exposure. A mass balance will also be established in the
study.

A single typical hair dye procedure per subject will be performed by a
professional hairdresser. Four hairdressers will be involved in the study.

The maximum amount of [14C]-radioactivity handled or to come in contact with
will not exceed 3.6MBq per subject in this study. This level of radioactivity
is chosen to gain reliable data on the systemic exposure of consumers to hair
dyeing. Based on recent human data, the physical-chemical properties of the
active ingredient (not volatile), the skin protection by gloves, the combined
reaction with the coupler (irreversible binding to the hair shaft), it is
expected that the dermal and inhalation exposure for the professional
hairdresser will be low to negligible. The latter was confirmed by the recently
conducted and reported hairdresser exposure study [2].
Possible skin contact with hair dye results in a radiation dose for the skin
and for the total body which is dependent on the fraction of radioactive
material to come in contact with skin, the fraction absorbed by the skin and
the penetration via the skin into the human body. Recently reported human data
in literature [1] show that the dermal penetration of PPD, directly in contact
for 30 minutes with bare skin, amounted on average to about 0.5% with a maximum
of 1.02%, expressed as percentage of the applied dose.
The Nuclear Research and Consultancy Group (NRG) has performed calculations on
the skin dose, the internal dose and the effective dose for an exposure
duration to the hair dye comparable to the daily life situation in hair dyeing
[3]. The effective radiation dose (body burden) per subject is estimated to be
maximally 0.025 mSv.

In conclusion, the radiation dose received by the subjects in this study will
be well below the Euratom dose limit (body burden; 0.025mSv) of 1mSv/year and
therefore their risk will only be slightly increased due to their participation
in this study.
Based on the fact that [14C] is a radiation emitter with low energy it is
concluded that risk for the professional hairdressers and workers in the
Clinical Research Unit is not enhanced.