Safety aspects of the nano TiO2 production and application

1
Safety aspects of the nano TiO2 production
and application

• Presentation at the Nano Safety Conference
• Ljubljana 22nd- 24th of April 2009
• Antonín Mlcoch

2
Content

• Preface
• Risk assessment framework of nano TiO2
• Common activities of TDMA
• Ongoing iniciatives
• Relative risk assessment for the several
  industrial fabrications of nano TiO2
• Conclusions

3
? World consumption of TiO2 5 mil t/year ?
World consumption of UF and nano TiO2 40 kt/
year (including 25
kt /year DeNOx catalysts) ?UF TiO2 has a long
history of safe use in cosmetics products
spanning many decades (UV Attenuator
) ?Nano TiO2 are also used in
catalysts,coatings for self-cleaning
windows,electronics,fotovoltaics and medicine ?
Czech Republic Precheza producer of the
pigmentary TiO2 and development of production
and application of the precursors for catalysts
, photocatalysts and UV absorbers
4
3 MARKETS REPRESENT 80 OF MARKET SHARE
40 000 Mt / Year estimated 2006
Spring 2008
5
The industry is responsible for the evaluation
of any such risks in production and application

• ? Attention focuses upon the questions of risk
  assessment and risk management within the first
  phase of application research
• ? Definition and structure of nanomaterials,
  toxicological and ecotoxicological behaviour of
  nanomaterials , exposure and need for specific
  nanoregulation
• I Is the whole life cycle (workers consumers
  disposal to
• the environment) under the control by the
  industry ?
• ? Is there information enough and has the
  relevant information
• distributed adequately?

6
Potential for exposure to nano TiO2
Risk Hazard x Exposure
Adapted from Tsuji J.S. all Toxicological
Sciences2006 89, No.1 ,42-50
7
Routes of exposure, distribution and
degradation of NSP
Adapted from Oberdörster G. Inhalation
Toxicology 2004
8
Adapted from Oberdörster G. Inhalation
Toxicology 16,2004,23-45
9
Common activities of TDMA TDMA Ultrafine TiO2
Working Group TDMA members Ishihara,Tayca,
Merck

• Assessment of substance risk is time consuming
  and
• costly procedure,multidisciplinary
  approach.
• ? Developing of an extensive dossier of safety
  data and other evidence which examine the various
  aspects of the consumer safety of UF TiO2 ? EC
  Directive TiO2 is safe for use in cosmetic
  products at maximum concentration of 25 in
  order to protect the skin
• Standartization of respirable dust measurement
  
• Review of Toxicology and Epidemiology of TiO2
  
• literature

TDMA Titanium Dioxide Manufacturers Association
A Sector Group of Cefic
10
Several basic studies sponsored by TDMA

• Historical Cohort Study of Workers Employed in
  the
• Titanium Dioxide Production Industry in
  Europe, Results of Mortality Followup Boffetta,
  et al Department of Medical Epidemiology
  Karolinska Institute, Stockholm, Sweden, January
  2003
• ? Subchronic Inhalation Toxicity Study on
  Pigmentary Titanium Dioxide in Mice,Rats ,and
  Golden Hamsters,
• Chemical Industry Institute of Toxicology
  (CIIT),2002
• ? Subchronic Inhalation Toxicity Study of
  Ultrafine Titanium Dioxide with Mice,Rats,and
  Golden Hamsters ,CIIT USA 2003

11
Inhalation Toxicology and Epidemiology
Subchronic, inhalation study CIIT Centres for
Health Research USA Rats, mice and
hamsters Photocatalytic TiO2 (Degussa P
25), Aerosol concentrations of 0,5 , 2 or 10
mg/m36 hours/day,13 weeks
Main findings of inhalation study
There is no evidence that titanium dioxide
itself has toxic properties,that would lead to
cancer. This recent study leads us to believe
that titanium dioxide does not present a
carcinogenic risk to man at exposures experienced
in the workplace.
12
?The results of our two mortality studies are
most powerful evidence that UF TiO2 does not have
a significant carnigonic effect on the human
lung. ?The studies do not suggest an association
between occupational exposure to TiO2 and risk
for cancer. ?Studies on application of sunsreens
containing UF TiO2 to healthy skin revealed that
TiO2 particles only penetrate into the outermost
layers of the stratum cornum,suggesting that
healthy skin is an effective barrier to TiO2
?Oral,subcutaneous and intraperitoneal
administration did not produce a significant
increase in frequency of any type of tumor in
mice and rats.
13
Occupational Exposure Limits
NIOSH,USA recommend new exposure limits of
1.5 mg/m3 for fine and 0.1 mg/m3 ultrafine TiO2
as time weighted average concentrations for up
to 10 hr/day during a 40-hours work week. These
levels will serve to minimize any risks that
might be associated with the development of
pulmonary inflammation and cancer. TDMA opinion
the lower limit for the critical dose of UF
TiO2 may be as high as 2 mg/m3.Hence ,REL of 1,5
mg/m3 would be protective for ultrafine
exposures.
14
Ongoing iniciatives

• In April, 2008 the European Commission requested
  additional information for nanoscaled material
  in cosmetics especially for TiO2 .The final
  dossier was submitted to EC 23.2.2009 .
• At the moment WG 4 of ISO Committee is preparing
  ISO/AWI 11937 Nanotechnologies - Nano-titanium
  dioxide as a technical specification, consisting
  of two parts characterization and determination
  and material specifications of certain
  applications (e.g. coatings, cosmetics, plastics,
  ceramics).
• Under WPMN there have been selected 14
  nanomaterials for which data should be gathered.
  If no data exists, it should be conducted by
  testing. Titanium dioxide is one of those
  substances selected. TDMA participation and data
  gathering

WPMN OECD Working Party on manufactured
nanomaterials
15
UF TiO2 Manufacture and Processing

• The main difference between ultrafine and
  pigmentary titanium dioxide is primary particle
  size.Primary particles form aggregates and
  agglomerates.The primary particle is not normally
  present as discrete particles
• The processes for manufacturing UF TiO2 are
  usually similar to that of pigmentary titanium
  dioxide ,having adopted many of the standard unit
  operations and process equipment from pigment
  technology .
• The UF and nano product can be sourced from the
  sulphate ,the
• chloride,hydrothermal process ,flame pyrolization
  or sol-gel method

16
Process Flow Diagram of manufacture UF TiO2
17
Relative risk assessment for the several
industrial fabrications of nano TiO2

• representative synthesis method was selected
  based on its potential for scale up and near-term
  potential for large-scale production and
  commercialization .
• A list of input and output materials,and waste
  streams for each step of fabrication was
  developed and entered into a database that
  included key process characteristics such as
  temperarature and pressure.The physical/chemical
  properties and quantities of the inventoried
  materials were used to assess relative risk based
  on factors such as volatibility,carcinogenity,flam
  mability,toxicity,and persistence
• The protocol ranks three categories of risk
  relative to a 100 point scale
• (where 100 represents maximum risk)
• incident risk,normal operation risk and latent
  contamination risk

18
Product ,manufacturing method Risk score for production process
Nano TiO2 through hydrolysis and calcination from TiCl4 62
Nano TiO2 by hydrothermal process 64
Nano TiO2 through hydrolysis and calcination from titanylsulfat 56
Refinered petroleum 76
aspirin 58
19
Conclusions from risk assessment

• The manufacture of nano TiO2 may present lower
  risks than of those of current activities such
  as petroleum refining, polyolefin production, and
  synthetic pharmaceutical production
• Almost as much as constituent substances in a
  process, differences in handling operations could
  have a marked effect on the final risk scores
• Recycling and successful recapture of materials
  play a key role in lowering normal operations
  risk score.

20
Risk Assessment of exposure to TiO2 nanoparticles
location hazard exposure risk
black session Minimal of the TiO2 is present as free particles zero zero
up calcination as above zero zero
calcination The presence of nanoparticles is higly unlikely Minimum exposure during normal duties minimalize
micronisation minimal because all the UF particles are in aqueous suspension zero exposure zero
final powder product The hazard is potentially there but indications are that the dust is essentially aggregated Exposure levels need to be established by the manufacturers possible
21
Results for safe procedures for handling nano TiO2
? The main hazards of the production and
application of nano TiO2 are
physiological hazards, i.e. by inhalation ?
Potential dust exposure occurs only in specific
areas of the plant ? Safe procedure for
manufactiring and handling nano TiO2 have
defined for each phases of activity ? Wastes of
nano TiO2 are not considered hazardous for
disposal into sanitary landfill or industrial
waste disposal landfill.
22
Conclusions
? The safety of nano TiO2 has been the subject
of numerous experimental and clinical studies and
has been fully demostrated. These studies show
no adverse systemic effects with nanoscale
titanium dioxide no skin penetration detected,
no skin irritant or sensitising potential, no
genotoxic potential, no toxic potential by the
oral route, no ecotoxicological potential. ?
Low potential to produce tissue inflammation by
inhalation. ? Limited human data are limited,
quantitative data are available from rodent
studies.To use these data in risk assessment ,a
reasonable approach for extrapolating the rodent
data to humans is required. ? Use the best
information available to make interim
recommendations on occupational safety and health
practises in the production and use of nano TiO2
23
? These interim recommendations will be updated
as appropriate to reflect new information ?
They will address key components of occupational
safety and health, including monitoring,
engineering controls, personal protective
equipment, occupational exposure limits, and
administrative controls . ? Additional are
required to make a better assessment (for example
NIOSH plans to study airborne exposures to fine
and ultra-fine TiO2 along with workplace
procedures and end useres in comparison with
unexposed workers last year European Commission
requested of additional information for nano
TiO2 in cosmetics.) ? TDMA members take all
possible precautions against all potential work
place exposures and support the continuous
improvement of procedures and processes to
minimalize any potential exposure
NIOSH National Institute for Occupational Safety
and Health,USA
24
Thank you for your attention
antonin.mlcoch_at_precheza.cz
Author acknowledge partial support for this work
from Ministry of Industry of the Czech republic
within the framework of state programme TANDEM