Earlier this week I wrote about the recent
publication of a notice of proposed rulemaking from DOT’s Pipeline
and Hazardous Material Safety Administration (PHMSA) proposing the latest set
of revisions to the hazardous material regulations (HMR) to harmonize those
regulations with international hazmat shipping rules. Today I would like to
address a specific portion of that NPRM; the classification process for
corrosive materials in accordance with 49
CFR 173.137.
Overview
In section 4 of the NPRM, PHMSA briefly describes the changes
to the HMR being proposed. With regards to the classification of corrosive
materials it notes:
“Alternative criteria for
classification of corrosive materials: PHMSA proposes to include non-testing
alternatives for classifying corrosive mixtures that instead uses existing data
on the chemical properties. Currently the HMR require offerors to classify Class
8 corrosive material and assign a packing group based on test data. The HMR
authorize a skin corrosion test and various in vitro test methods that do not
involve animal testing. However, data obtained from testing is currently the
only data acceptable for classification and assigning a packing group. These
alternatives would afford offerors the ability to make a classification and
packing group assignment without the need to conduct physical tests.”
PHMSA is also proposing to update the incorporation by
reference OECD Guidelines for the Testing of Chemicals to the 2015 version.
Specifically, for the testing of corrosive materials for determination of
packing group determination, this will affect OECD tests 404, 430, 431, and 435.
Along with the similar change to the definition of
‘corrosive material’ in 173.136, PHMSA is proposing to remove the phrase “full
thickness destruction” and replace it with “irreversible damage” in all
instances where it occurs in 173.137.
PHMSA is not proposing to
add additional corrosivity testing protocols in this NPMR.
Corrosion Classification Alternatives
The proposed regulation provides two non-testing
alternatives to determine the packing group containing mixtures of chemicals
including one or more previously tested corrosive chemicals. The first, bridging
{§173.137(d)(1)},
would be used when “there is sufficient data on both the individual ingredients
and similar tested mixtures to adequately classify and assign a packing group
for the mixture”. There are five bridging principals that could be applied to
mixtures under this provision:
• Dilution;
• Batching;
The second technique is the calculation method
{§173.137(d)(2)}. This
technique uses known concentration data and regulatory information from the Hazmat
Table to calculate which packing group a product would be in. A proposed
Appendix I helps translate the calculations into actual packing group
determination.
Calculation Process
By their very nature, regulatory documents are not real
clear in explaining how a process will work. After some careful reading of the
NPRM and the proposed changes to §173.137
and the new Appendix I, this is how I see the calculation process working.
First, someone is going to have to make a technical determination
of whether or not any interactions (or chemical reactions) will enhance the
corrosive effects of any of the constituent materials. It that determination is
positive, then physical testing will be required, or the organization will have
to assume PG I status for the material.
Next all of the corrosive constituents of the product will
have to be identified. The Hazmat Table (§172.101
table) will then be used to determine the packing group and any minimum
concentration limit associated with that material in the Table. That minimum
concentration limit is called the ‘specific concentration limit (SCL)’ in this NPRM.
Unfortunately, it is not specifically defined.
The first calculation will only involve PG I corrosive constituents
of the product. For each PG I corrosive constituent the ratio of its
concentration in the product to the SCL will be determined. For most corrosive
materials, the Hazmat Table does not provide an SCL; for those chemicals a
generic concentration limit (GCL; again, not specifically defined in the NPRM)
of 1% will be assumed for this initial calculation. The sum of all of the
PG1/SCL(GCL) ratios will be determined. If that sum is greater than or equal to
one, Calculation #2 will be completed. If the sum is less than 1%, Calculation
#3 will be completed.
Calculation #2. Again, just the concentration and GCL for
the PG 1 corrosive materials in the product will be used. In this case (and in
all subsequent calculations) the GCL will be equal to 5% and the concentration ratios
for all PG I will be recalculated. If the sum of those ratios is greater than
or equal to 5% then the material will be classified as Class 8, PG I. If the
sum of those ratios is less than 5%, the material will be classified as Class
8, PG II.
Calculation #3. This calculation will use the same data from
all PG I and PG II chemicals in the material being classified. Where a SCL is
provided it will be used in the ratio calculation described above. Otherwise, a
GCL of 5% will be used. The ratios for each of the PG I and PG II chemicals
will be summed. If the sum is greater than or equal to 5%, the material will be
classified as Class 8, PG II. If the sum is less than 5%, Calculation #4 will
be completed.
Calculation #4. This calculation will use the same data from
all PG I, PG II and PG III chemicals in the material being classified. Where a
SCL is provided it will be used in the ratio calculation described above. Otherwise,
a GCL of 5% will be used. The ratios for each of the PG I, PG II and PG III
chemicals will be summed. If the sum is greater than or equal to 5%, the
material will be classified as Class 8, PG III. If the sum is less than 5%, the
material will not be classified in Class 8.
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