Nanomaterial Aquatic Toxicity Tests
Below is a short report on experiments that we performed with in collaboration with the University of Connecticut. Similar testing can be performed on any variety of materials to determine their toxicity. Please contact me for details on any testing that you might be interested in performing.
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Craig A. Calvert, Ph.D., C-CHO
February 2011
In recent years the use of nanotechnology through the development of nanomaterials has increased rapidly. A graph of the number of papers published with nano used in the title is given below to illustrate the rapid growth from minimal pre-1990 level to a peak in 2009. The slight dip is likely due to the economic downturn. The increased use of the materials has sparked many debates over the toxicity of nanomaterials. Since size plays a large role in reactivity, groups are debating the need for regulating nanomaterials. The most likely regulation to oversee nanomaterials is EPA’s Toxic Substance Control Act (TSCA). TSCA regulates materials based on composition, and since most nanomaterials are the same composition as the bulk material, there was no immediate regulatory requirement. However, EPA has clarified that nanomaterials must follow TSCA testing requirements and reporting in Section 4 and 8. On September 17, 2010, EPA issued a significant new use rule (SNUR) notice under TSCA for single and multi-walled carbon nanotubes that are used in applications such as advanced composites, fuel cells, and electronics.
www.tscaconsulting.blogspot.com/2010/09/epa-issues-final-snurs-for-carbon.html
Because of the TSCA reporting requirements and the potential for increased reactivity, toxicity testing of nanomaterials is important in understanding the potential risks posed by these materials.
www.tscaconsulting.blogspot.com/2010/09/epa-issues-final-snurs-for-carbon.html
Because of the TSCA reporting requirements and the potential for increased reactivity, toxicity testing of nanomaterials is important in understanding the potential risks posed by these materials.
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Figure 1. A plot of number of papers published with
“nano” in the title versus the year. The search was
performed using Google Scholar.
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The toxicity of several inorganic nanoparticles was studied. These studies used 48-hour static acute toxicity tests on a freshwater crustacean (Daphnia pulex) and small fish (minnow). In general terms, these tests added the nanomaterials to a beaker of water with the organisms and then the combination was left to sit for 48 hours. After 48 hours, the number of surviving organisms was counted and used to calculate the survival percentage. The results showed that the survival percentages depended on the concentration of the nanomaterials added to the beaker and the type of nanomaterial used. These tests were looking for the relationship between different nanomaterials with nanosilver as the control; no bulk material control was used. Silver is commonly used as an antimicrobial due to its toxicity. The results of this study confirms that silver is highly toxic and that the toxicity of the nanomaterials is based on the type of material.
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| Table 1. Results of nanomaterial toxicity testing. |
