Supporting Information

The Structure, Composition and Dimensions of TiO2 and ZnO Nanomaterials in Commercial Sunscreens

Zuzanna A. Lewicka1, Angelo F. Benedetto2, Denise N. Benoit3, William W.Yu3, John D. Fortner3 and Vicki L. Colvin3*

1Department of Electrical and Computer Engineering

6100 Main Street MS-60, Rice University, Houston TX 77005

2Smalley Institute for Nanoscale Science and Technology

6100 Main Street MS-100, Rice University, Houston TX 77005

3Department of Chemistry

6100 Main Street MS-60, Rice University, Houston TX 77005

*Corresponding author

Phone: 713-348-5741

Fax: 713-348-2578

E-mail:

Figure S1 Photographs of the labels on the sunscreen 05 (A) and 07 (B).

Figure S2SEM images at low magnification level (1,000x) for the “as-provided” samples (00-08).

Figure S3SEM images at high magnification level (50,000x) for the “as-provided” samples (00-08).

Figure S4TEM images of the “diluted” samples (00-07) and the particles obtained from companies (T-Avo, T-Eco, Z-Cote).

Sunscreen sampling and market estimation

Figure S1 Photographs of the labels on the sunscreen 05 (A) and 07 (B).

Figure S2SEM images at low magnification level (1,000x) for the “as-provided” samples (00-08). All images have the same scale bar of 25 µm.

Figure S3SEM images at high magnification level (50,000x) for the “as-provided” samples (00-08). All images have the same scale bar of 500 nm.

Figure S4TEM images of the “diluted” samples (00-07) and the particles obtained from companies (T-Avo, T-Eco, Z-Cote). All images have the same scale bar of 100 nm.

Sunscreen sampling and market estimation

Four popular retail stores in the US (CVS, Target, Wal-Mart and Walgreens on September 26th and 27thof 2009) were chosen to estimate percentage and mass of inorganic pigment material from sun protection products. Inorganic ingredients (both active and inactive) were analyzed that were listed on the product labels of lotions and creams with SPF 15 and higher. Both “primary” sunscreens (intended to provide users with sun protection when they go outside) and “secondary” sunscreens (e.g. daily moisturizer, intended for casual sun protection) were examined (FDA 1999).

For each store there were ~130 sun protection products with SPF 15 or higher.The average price is about $10 per unit (~ 100 g). 66 % of these products were primary sunscreens. 54 % of all the examined products listed an SPF 30, including 55+, 70+, 85+, and 100+. Generally, all analyzed products claim a protection against both UVA and UVB wavelengths. 23 % of the investigated sun protection products labeled TiO2 and/or ZnO as active or inactive ingredients. Generally, ZnO was labeled as an active ingredient but 12 % of the products labeled TiO2 as an inactive ingredient. TiO2 was labeled as an inactive ingredient mostly on the secondary sunscreens without weight percentage specification.The weight fraction of TiO2 and ZnO ranged from 1.9 – 14.5 wt % (average 8.2 wt %).

Based on the above-mentioned data and the reports for global and US sunscreen markets, it is possible to estimate how much inorganic pigment materialsare being used by consumers (Datamonitor 2009a, b). Global revenue for sunscreen products was estimated at $5.1 billion (a volume of 532.3 million units) for the year 2008, according to Datamonitor. Sunscreen market includes after-sun, self-tan and sun protection products. However, sales of sun protection products account for 65.7 % of the global market (a volume of 349.7 million units). The US sunscreen market generated revenue of $1.1 billion in 2008, which was 21.6 % of the global sunscreen market. Assuming that 23 % of all sun protection products in the US contain TiO2 and/or ZnO and considering an average of ~ 100 g of sunscreen formulation per unit (bottle) and each unit contains an average of 8.2 wt % of inorganic pigment materials, an estimated 142 tons of inorganic pigments (TiO2, ZnO) are used and released per year (in the US) via sunscreen products alone. It has been forecasted that the sales of sunscreen products reach a value of $6 billion (a volume of 603.1 million units) in 2013.

References

Datamonitor (2009a) Personal hygiene / personal care United States Industry Guide. Accessed 12 September 2010

Datamonitor (2009b) Suncare Global Industry Guide 2009. Accessed 12 September 2010

FDA (1999) Sunscreen drug products for over-the-counter human use, final monograph, federal register /vol. 48, no. 98.

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