There are conflicting views as to whether PTC papers are safe to use in school genetics classes.1,2,3 The use of this test is not permitted in W.A. Department of Education schools4, but we are not aware of bans in any other Australian jurisdiction. PTC is toxic, however, the amount of PTC on one commercially produced PTC paper is very small; students who can taste the bitterness would be able to detect it immediately from one test paper. However, for non-tasters, there may be a temptation to repeat the test with one or more papers. See our previous answer on this topic: Genetics.
Rather than use PTC papers to test for bitterness-tasting ability, we suggest that schools consider substituting non-hazardous substances such as the juice of broccoli or kale, or the use of genetics test papers that use much less toxic chemicals such as sodium benzoate. Other genetic traits could also be observed such as: ear lobe attachment, widow’s peak hairline; tongue rolling; pigmented iris of the eye; naturally curly or straight hair; hand clasping; dimples; see http://learn.genetics.utah.edu/content/basics/observable/
- ‘Safety Questions – PTC Paper’ Science Teachers’ Association of Ontario blog. https://staoblog.org/2015/03/23/safety-questions-ptc-paper/ (Accessed July 2015)
- Texley J., T. Kwan and J Summers 2004. Investigating safely. National Science Teachers Association Press. Virginia, U.S.A. p.80 https://learningcenter.nsta.org/resource/?id=10.2505/PKEB166X3
- Merrit, Robert B., L.A. Bierwert, B. Slatko, M.P. Weiner, J. Ingram, K. Sciarra and E. Weiner 2008. ‘Tasting Phenylthiocarbamide (PTC): A New Integrative Genetics Lab with an Old Flavor’. The American Biology Teacher, 70(5):e23-e28:27 http://www.bioone.org/doi/full/10.1662/0002-7685(2008)70[23:TPPANI]2.0.CO;2 (Original link replaced: March 2018)
- WA Department of Education. 2014 'Banned and restricted hazardous substance and experiments in schools August 2014'
Drewnowski, Adam and Carmen Gomez-Carneros. 2000. ‘Bitter taste, phytonutrients, and the consumer: a review 1, 2, 3’ American Journal of Clinical Nutrition 72:1424–35 https://academic.oup.com/ajcn/article/72/6/1424/4729430
‘Learning Genetics with Paper Pets’ 2006. NSTA website. http://www.nsta.org/publications/news/story.aspx?id=51647
‘Observable Human Characteristics’. University of Utah website. http://learn.genetics.utah.edu/content/basics/observable/ (Accessed August 2016)
‘PTC: Genes and Bitter Taste’. University of Utah website. http://learn.genetics.utah.edu/content/basics/ptc/ (Accessed August 2016)