Summary of Comment Responses for PMNs P-06-36 and P-06-37

EPA Docket ID: EPA-HQ-OPPT-2010-1075

June 2012

Comment 1: In the proposed SNUR, EPA clarified that it considers nanomaterials to include 

substances with a particle size less than 100 nanometers where d10 particle size presents the 

particle size as determined by laser light scattering at which 10 percent by weight of the 

substance measured is smaller. We support this approach based on the need for a threshold since 

solid particulate material will contain a distribution of particle sizes. The 10 percent threshold 

strikes a reasonable balance between being adequately protective of human health and 

recognizing practical limitations associated with analytical methods available for quantifying 

materials at or below such a threshold. We support using the weight-based threshold, as methods 

and instrumentation for performing weight-based particle size measurements are more widely 

available than techniques for performing measurements based on particle number. There are 

other important elements that should be included in any definition of a nanomaterial including 

recognizing that aggregates and agglomerates are not the same as the primary particles of which 

they are comprised and that many agglomerates may not disagglomerate readily in any medium. 

EPA Response: In the proposed rule, EPA did not attempt to clarify what it considers to be a 

definition of a nanomaterial, although particle size of less than 100 nanometers (nm) is often 

used to describe such chemical substances. Based on information contained in the PMNs, EPA 

believes that the PMN submitter is not manufacturing or processing the PMN substances with a 

d10 particle size less than 100 nm. EPA also believes it is possible that these chemical 

substances could be manufactured or processed with a d10 particle size less than 100 nm. EPA 

proposed a new use in the SNURs for these two PMN substances to require notification if those 

chemical substances were manufactured or processed with a d10 particle size less than 100 
Summary of Comment Responses for PMNs P-06-36 and P-06-37

EPA Docket ID: EPA-HQ-OPPT-2010-1075

June 2012

nanometers. Upon notification of this new use, EPA would review the properties and assess any 

potential risks that were different from the chemical substances as reported in the PMNs. While 

EPA believes that the threshold and method used to measure particle size for these PMN 

substances is appropriate and protective of human health, EPA will consider different thresholds 

and methods in other TSCA actions, depending on the chemical substances being measured and 

available scientific knowledge and technology.

Comment 2: The PMN substances are not nanoscale substances and any concerns or regulatory 

requirements derived from concerns related to nanoscale materials are not pertinent to the PMN 

substances.

EPA Response: As described in the consent order, the basis for EPA’s concern for the PMNs, is 

not whether the substances constitute nanoscale materials but rather the fact that they qualify 

under the new chemicals category for respirable, poorly soluble particulates, under the 

subcategory of titanium dioxide. (See http://www.epa.gov/opt/newchems/pubs/chemcat.htm.) The

category document identifies that there is potential for respirability if workers handle material 

containing any particles less than or equal to 10 microns in diameter. Based on information in the 

PMNs, workers are likely to be exposed to particles less than or equal to 10 microns in diameter. 

In addition, based on information contained in the PMNs, EPA believes that manufacturers and 

processors could use these chemical substances at particle sizes less than 100 nm. Accordingly, 

EPA has proposed new uses that would enable EPA to review any manufacture or processing of 

the PMN substance without the use of appropriate respiratory protective equipment or 

engineering controls, or at particle sizes less than 100 nm. The purpose of these notifications 
Summary of Comment Responses for PMNs P-06-36 and P-06-37

EPA Docket ID: EPA-HQ-OPPT-2010-1075

June 2012

(i.e., SNUNs) is to allow EPA to review any new properties and assess any potential risks 

presented by the new use.

Comment 3: EPA’s risk assessment stated there is no exposure expected to the PMN substances, 

according to the Human Health Effects Summaries in the Consent Order. EPA determined that 

there can be no risk warranting regulation under the proposed rule, because of the statement that 

no absorption of the PMNs is expected via any route of exposure if the PMN substances are 

produced via the calcination method. The PMN substances can only be manufactured using the 

calcining process and there is no known alternative industrial process for making chemical 

substances such as the PMN substances. Based on review of EPA’s risk assessment and the 

extensive experience of industry members with similar products, there is no substantiation of 

potential risk in the record for the proposed rule or the necessity for any regulation of the PMN 

substances.

EPA Response: The Human Health Effects Summary, contained in Unit IV. (“EPA’s 

Assessment of the Risk”) of the Consent Order does not address potential exposures to the PMN 

substances; workplace inhalation exposures are addressed in a separate Exposure Summary of 

the same Unit IV. The health effects summary does state, however, that if the PMN substances 

are calcined then EPA does not expect the PMN substances to be absorbed by any route of 

exposure. In addition, the health effects summary identifies concerns for potential lung effects 

from exposure to the PMN substances, according to the chemical category for respirable, poorly 

soluble particulates under the subcategory of titanium dioxide. (See

http://www.epa.gov/opt/newchems/pubs/chemcat.htm.) There is concern for the potential lung 
Summary of Comment Responses for PMNs P-06-36 and P-06-37

EPA Docket ID: EPA-HQ-OPPT-2010-1075

June 2012

effects when workers handle material containing particles less than or equal to 10 microns in 

diameter. Based on information in the PMNs, workers are likely to be exposed to particles less 

than or equal to 10 microns in diameter. The concern for lung effects is not mitigated by 

calcination; the concern is independent of potential for absorption. In fact, because these 

insoluble particles are not absorbed, they remain in the lung longer than other particles, causing 

further inflammation and lung effects. As mentioned earlier in this response, the Exposure 

Summary in the consent order identifies potential inhalation to workers. Based on the potential 

hazard and exposure to workers, EPA concluded that the PMN substances may present an 

unreasonable risk of lung effects to exposed workers.

Comment 4: EPA should clarify that the PMN substances are not salts. It is incorrect for EPA to 

characterize these chemical substances as salts. EPA’s health risk analysis based on structural 

analogs does not demonstrate a risk warranting regulation because the regulated substances do 

not exhibit the properties of the constituent metals and do not represent an unregulated dust 

exposure. Titanium dioxide is not an analog surrogate for the PMN substances. EPA’s 

assessment should evaluate the risk of the finished crystal form of the PMN substances.

EPA Response: EPA is not characterizing the PMN substances as salts or metals, and the 

structural analogy in the consent order was not based on analogy to salts or constituent metals. 

EPA’s structural activity relationship (SAR) analysis was based on the category of respirable, 

poorly soluble particulates that cause lung effects as a result of inhaling particles. (See

http://www.epa.gov/opt/newchems/pubs/chemcat.htm.). Titanium dioxide was chosen as the 

subcategory based on its physical characteristics as a poorly soluble particulate, and not any 
Summary of Comment Responses for PMNs P-06-36 and P-06-37

EPA Docket ID: EPA-HQ-OPPT-2010-1075

June 2012

chemically-mediated toxicological properties. The risk assessment, as described in the response 

to the comment 3, is consistent with the Agency’s concerns that potential exposure to particles of 

the finished crystal form of the PMN substances may cause an unreasonable risk of lung effects.

Comment 5: EPA relied on a recommended exposure level (REL) from the draft National 

Institute for Occupational Safety and Health (NIOSH) Current Intelligence Bulletin: 

Occupational Exposure to Titanium Dioxide as the source of the proposed NCEL of 1.5 mg/m3

. 

Since the final NIOSH intelligence bulletin set a higher REL of 2.4 mg/m3

, EPA should revise its 

risk assessment to incorporate this new information.

EPA Response: EPA agrees that using the REL of 2.4 mg/m3 for titanium dioxide, from the final 

NIOSH bulletin, would be more appropriate. This document is located in the docket under 

docket ID number EPA-HQ-OPPT-2010-1075. In fact, paragraph (b)(2) of the New Chemical 

Exposure Limit of the consent order for the PMN substances contains an automatic sunset clause 

stating that the NCEL in the consent order would automatically and immediately be changed to 

the final REL for titanium dioxide issued by NIOSH. Accordingly, EPA will issue the final 

SNURs with a NCEL of 2.4 mg/m3, based on the final NIOSH REL for titanium dioxide. 

However, because EPA estimates that there are potential exposures greater than 2.4 mg/m3

, EPA 

continues to find a potential risk of concern for the PMN substances.

Comment 6: These chemical substances are subject to existing Occupational Safety and Health 

Administration (OSHA) Permissible Exposure Levels (PELs) for inorganic tin compounds. 

Given the existing applicable OSHA PELs, the proposed SNURs are duplicative and 
Summary of Comment Responses for PMNs P-06-36 and P-06-37

EPA Docket ID: EPA-HQ-OPPT-2010-1075

June 2012

unnecessary regulation. The NCELs provisions in the 5(e) orders state that the NCEL and 

respirator requirements are automatically nullified if OSHA promulgates a PEL for the same 

substance. There is a separate OSHA standard, applicable to all inert dust particles, of 5 mg/m3

. 

There is no need for EPA to require the development of additional and different regulatory 

monitoring techniques for the PMN substances because there are already analytical monitoring 

techniques developed for inorganic tin compounds and inert dust particles.

EPA Response: While the OSHA PEL for inorganic tin compounds would be applicable to the 

inorganic tin contained in the PMN substances, it does not apply to the PMN substances 

themselves. Based on information submitted in the PMNs, EPA considers the substances to be 

mixed metal oxide compounds. Other comments make the argument that the constituent metals 

are not bioavailable and there should not be concern for exposure to bioavailable metals from the 

PMN substances. EPA is not characterizing the PMN substances as metals and the basis of its 

risk assessment is not the constituent metals contained in the PMN substances. See EPA’s 

response to comment 4. While there is an OSHA inert dust standard of 5 mg/m3

, EPA finds there 

is still a potential risk for lung effects from exposures less than 5 mg/m3 for the PMN substances. 

Paragraph (b)(2) of the New Chemical Exposure Limit of the consent order for the PMN 

substances does state, that if OSHA promulgates a PEL specifically applicable to the PMN 

substances then the respirator requirements and NCEL become null and void. This paragraph 

(b)(2) also states that the requirements of the consent order are not negated by any pre-existing 

OSHA PEL, such as the PEL for inorganic tin compounds cited by the commenters. Because 

OSHA has not promulgated a PEL specifically applicable to the PMN substances, the respirator 

requirements and NCEL requirements in the consent order for the PMN substances remain in 
Summary of Comment Responses for PMNs P-06-36 and P-06-37

EPA Docket ID: EPA-HQ-OPPT-2010-1075

June 2012

effect. Neither the PMN submitter nor commenters have supplied any information on whether 

existing monitoring techniques used for inorganic tin compounds would be appropriate for use 

with the PMN substances. EPA has issued the consent order and will issue the final SNURs with 

the NCEL provisions to allow for review of any monitoring techniques for the PMN substances 

that would be used to demonstrate compliance with the exposure limits.

Comment 7: The costs and economic impacts of the rule are underestimated significantly. 

Customers may not use the PMN substances because of compliance costs. Manufacturers of the 

PMN substances will incur costs as a result of complying with the SNUR requirements, and costs 

associated with submitting a significant new use notice, including submitting toxicological 

testing prior to manufacture or import of the PMN substances for a significant new use.

EPA Response: The economic assessment developed by EPA for this rule estimates and 

discusses the potential costs identified by the commenter. The commenter did not supply any 

additional information disputing EPA’s specific cost estimates or conclusions. Therefore, EPA 

will not change any of its cost estimates or conclusions. Contrary to the commenter’s assertions, 

the SNURs do not require testing, and submission of a SNUN does not require submission of 

toxicological testing. The preamble to the proposed SNURs did recommend testing that could 

address potential risks EPA has identified for the PMN substances, and states that SNUN 

submitters can submit any other data to address potential risks. Anyone submitting a SNUN is 

strongly encouraged to submit information addressing potential risks, but specific testing is not 

required.
Summary of Comment Responses for PMNs P-06-36 and P-06-37

EPA Docket ID: EPA-HQ-OPPT-2010-1075

June 2012

Comment 8: EPA’s economic assumptions pursuant to the Regulatory Flexibility Act do not 

reflect the current market. Nearly identical structural analogs of the PMN substances already on 

the TSCA Inventory are produced by companies in the United States and abroad. The PMN 

substances are produced abroad and imported in finished articles.

EPA Response: The commenter did not supply any information on present or future significant 

new uses by small or large entities of the substances subject to the SNURs. Therefore, the basis 

for EPA’s finding under the Regulatory Flexibility Act, that the promulgation of the SNURs will 

not have a significant adverse economic impact on a substantial number of small entities, will 

remain unchanged in the final rule.

Comment 9: The rule would prevent U.S. manufacturers from manufacturing and using the 

PMN substances in finished products while the rule would not prevent the use of the PMN 

substances outside the United States. Foreign manufacturers of finished products containing the 

PMN substances will be able to use the PMN substances and import them as part of articles 

exempt from TSCA reporting.

EPA Response: TSCA primarily addresses risks within the United States. The Consent Order 

and the SNURs do not prevent U.S. manufacturers from manufacturing and using the PMN 

substances in finished products. In fact, the Consent Order negotiated with the PMN submitter 

allows manufacture, subject to certain restrictions. Those restrictions are reflected in the SNURs. 

The SNURs exempt all manufacturers and processors from significant new use reporting once 
Summary of Comment Responses for PMNs P-06-36 and P-06-37

EPA Docket ID: EPA-HQ-OPPT-2010-1075

June 2012

the PMN substances have been incorporated into a polymer, glass, dispersion, cementitious 

matrix, or a similar incorporation. This includes articles imported into the United States. For 

these uses, no significant exposures are expected. The Consent Order and the SNURs would only 

be applicable in the United States to manufacturers or processors of the PMN substances in 

particulate form. EPA issued the Consent Order and is issuing the SNURs to address potential 

worker exposures associated with manufacture and processing of the PMN substances that could 

result in a risk of lung effects.

Comment 10: There are economic and environmental benefits identified in the PMN 

submissions for these chemical substances. Specifically, the PMN substances are intended to 

replace pigments containing heavy metals such as lead and cadmium which are associated with 

risks to human health and the environment.

EPA Response: While EPA agrees that it would be beneficial to replace pigments that contain 

lead and cadmium, EPA found that the potential unreasonable risks associated with the PMN 

substances warranted issuing a consent order and significant new use. 

Comment 11: EPA received one comment opposing the approval of the use of 2,4-D.

Response: Since this SNUR is only applicable to the chemical substances contained in PMNs P06-36 and P-06-37 and not 2,4-D, EPA will not address this comment.