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PAINT AND COATINGS MANUFACTURING: BIOCIDES

Regulatory authorities re-evaluation account only for dermal uptake, but not the transfer

cannot continue to into systemic circulation, considering when a system (not a local
toxicological endpoint) is used to determine the POD for risk calcu-
systematically ignore the lations. As such, it renders dermal adsorption values unnecessarily
high. Hence, the extent of dermal exposure that is utilized in
negative economic impact re-evaluations is then considered much too conservative and
which would not be encountered in the real-world application of
paint products containing the biocides being evaluated.
of their evaluations, Some biocide chemistries may negatively impact critical paint
properties including, but not limited to, color, tint strength, gloss,
especially in the context of scrub, and stain resistance. Paint manufacturers are therefore
reluctant to alter their preservative packages. The sophistication
a very limited number and uniqueness of paint and coatings formulations makes it diffi-
cult to select a preservative. The selection of a biocide is governed
of preservatives remaining by a variety of factors, and it must be understood that “one biocide
does not fit all”. Use of an alternative, of a similar chemistry or very
in Canada for paint different chemistry, requires a significant investment of resources,
both financial and personnel, to test a variety of paint properties
formulators. that could be impacted by further restrictions. Of greater concern
is the dry film preservative because replacement of a dry film
biocide requires a minimum of three to five years of exterior expo-
sure on a test fence or substrate in the region(s) in which the paint
product will be sold.
The value of the LCA would not necessarily be on the biocide Regulatory authorities must also integrate socio-economic
itself, but as it relates specifically to the function and role within a studies into the re-evaluation process for biocides. Regulatory
product system or formulation. By doing so, the LCA could capture authorities cannot continue to systematically ignore the negative
the benefits that preservatives provide in the system versus just economic impact of their evaluations, especially in the context of a
focusing on their footprint. It is an important overall consideration very limited number of preservatives remaining in Canada for
with respect to product stewardship generally. A lifecycle assess- paint formulators. Rather than further reducing current use rates
ment would capture the environmental performance of various and banning more preservatives through individual assessments,
architectural coating preservative scenarios used to determine the risk assessors must carefully examine health effects along with
environmental impacts and benefits that wet-state and dry-film economic effects, possible alternatives, availability and function of
preservatives provide in architectural coating systems. It would biocides, etc. Then, jointly with industry, consider all options avail-
also provide necessary insight on how reducing, eliminating, or able for certain problematic types of formulations and related
replacing certain preservatives can impact the coatings’ overall risks. This is typically done in the United States late in the
sustainability profile. It can also reveal how substitutions can alter evaluation process, and after the risk evaluation is completed.
the efficacy of those products and thereby increase product losses, It can also be done concurrently with the risk evaluation. CPCA
environmental wastes and, indeed, health issues. suggests a process be established to address such matters outside
While preservatives have been reported to cause both local and the formal re-evaluation process, which can be incorporated, when
systemic effects, the use of these assumptions for risk calculations and as needed, for specific biocides. This is critical for alignment
associated with systemic endpoints will require further considera- in a highly integrated value chain.
tion of the mechanics that govern substance transfer from the site Canadian paint formulators should also be able to use non-
of exposure to systemic circulation. This is especially critical in PMRA registered biocides in paint mixtures that are destined for
light of the fact that PMRA recently used critical systemic toxico- exports to countries where they have been risk assessed and are
logical endpoints that were remote from the site of exposure such considered safe to use. The very rigid position currently taken by
as thyroid effects, reproductive and developmental toxicity, rather the PMRA is incomprehensible. It means that Canadian paint
than local toxicological endpoints in selecting points-of departure formulators cannot use certain biocides to treat paint articles for
(PODs) for risk calculations. This is a critical deviation from export only to the United States and throughout the world. This is
standard practice for biocide evaluation and overstates the risks by another socio-economic aspect that must be examined closely in
a significant margin. any future decision in Canada. n
Evaluation of biocides must accept the fact that: 1) exposure via
dermal contact is a two-step process involving dermal uptake and Gary LeRoux is President and CEO of the Canadian Paint and
transfer into systemic circulation; and 2) that systemic transfer Coatings Association. www.canpaint.com
following dermal uptake is in fact minimal. The dermal exposure
values often assumed by Regulatory Authorities in their risk
50 CANADIAN FINISHING & COATINGS MANUFACTURING JANUARY/FEBRUARY 2021