Science Buddies: "Ask an Expert"

I am considering this as a topic for my science project. I have read about the increasing amount of pharmaceuticals found in public waterways. I live on a creek and we have a large hospital and also a mental institution in my town. I have also read that current waste water treatment plants do not filter out pharmaceuticals. What do you think about a project where I would obtain small quantities of several pharmaceuticals, calculate the correct strength of a solution to correlate to the published pharmaceutical levels detected in my area and expose Daphnia to these levels and observe how this affects the Daphnia's heart rate and survival. I checked with my local pharmacy tonight and was told that if a doctor will write me a prescription i can obtain one pill. Alternatively I can ask around to see if any of my neighbors take any of the medications on the detected list and use one of their pills. Thank you for any advice.

Hi,
Daphnia are wonderful creatures to use in toxicity testing, and there is a lot of attention currently on pharmaceutical presence in ground water. Have you thought about contacting your local waste water treatment facility? They may be able to provide some samples of local waters with known quantities of certain substances. If they cannot help you, then perhaps think about examining other products that could contaminate your local waters that you can buy locally (i.e. herbicides,pesticides, or even caffeine). Also there are some medications that you can purchase over the counter, like ibuprofen.

Here is a wonderful paper to give you some ideas regarding water contamination by pharmaceutical or other personal care products.
https://www.crops.org/publications/jeq/ ... /39/4/1173

Thanks,
Jenny

Hi there,

What a fabulous idea for a project!

Here is the Science Buddies project information regarding the use of Daphnia to study water toxicity:
https://www.sciencebuddies.org/science- ... p043.shtml

Here is a link to a previous Ask an Expert thread that might help you with some troubleshooting for your project:
https://www.sciencebuddies.org/science- ... =25&t=7695

Finally, the ScienceBridge program (http://sciencebridge.ucsd.edu) has a project called Environmental Spices, which looks at the toxicity of kitchen spices (like cinammon and vanilla) on Daphnia. The methods for this project are very straightforward, and may help you when figuring out how to carry out your project with the pharmaceuticals. (The website is down right now, but look for links to the Socrates program when you go to the website.)

I hope that helps! Let us know if you have more questions along the way.

Heather

Hi,

This is a really great project idea with so many variations possible. FunScientist and HeatherL have given you some really good suggestions and I have some more ideas that should help:

1. Daphnia toxicity testing is a very sensitive, general all-purpose method for measuring toxicity. You can use it to measure toxicity in local water sources, as FunScientist has suggested, or set up a test to measure the toxicity of specific substances, as Heather has recommended. Do not use any prescription drugs, as these are not allowed in a science project:

https://www.sciencebuddies.org/science- ... chem.shtml

2. Do you have Daphnia available to set up an experiment right away? If you have a culture of Daphnia growing, you will want to use the smallest Daphnia to start the experiment. Daphnia only live for 45-60 days, depending on the temperature, so if you start with mature adults, some may die of old age during the experiment and this will affect your results. The standard method calls for using Daphnia that are less than 24 hours old, so you want to start with very small, young Daphnia to ensure getting good results.

http://www.oecd.org/dataoecd/17/21/1948249.pdf

3. You need to decide what to use as a control. You can’t use distilled water because Daphnia require calcium and other elements that are usually available in tap water. Tap water contains chlorine, which is toxic to Daphnia, so you will need to get a water conditioner from a local aquarium store and treat the tap water a day before you start your experiment. Check the following website and with your local water company to ensure that the control water will be suitable for the Daphnia.


http://www.caudata.org/daphnia/

4. Here is a good way to count Daphnia to transfer into the control and experimental containers. Working outside with natural sunlight, use a transfer pipette or eye dropper and transfer the Daphnia to a very shallow white ceramic dish. You will be able to see the individual Daphnia and you can select 5 or 10 to transfer another dish. Once you have verified the count, have a second person count the Daphnia again. Gently swirl the dish and pour all at once into the control or sample container. Check the surface of the container to make sure no Daphnia are trapped on the surface because of air bubble in their carapace. You will understand the reason for the details after you have tried this.

5. Daphnia can be used for acute toxicity testing, where you count the number of mobile Daphnia after 24 or 48 hours, or for chronic testing where you start feeding the Daphnia after 24 hours and let them reproduce for 14 days. Daphnia reproduce by parthenogenesis and can have 3-10 babies every 3-4 days under optimum conditions. If you decide to test the toxicity of the individual substances, then the acute test is fine. If you decide to obtain local water samples, then I recommend doing the 24 hour and the 2-week test. The chronic toxicity test is a reflection of long-term toxicity that is associated with carcinogens and other chemicals that cause long-term health problems, so will very pertinent to your investigation.

6. Set up your experiment in duplicate, and if possible, in triplicate, even if this means you won’t be able to do as many samples as you want to. The temperature is very important, so keep your samples as close to 72 degrees F (but you will report this as 22 degrees C since this is a science project.) Do record the temperature at the beginning and end of your experiment.

You have just time enough to do a really great project if you can start it soon. Let us know if you have any questions.

Donna Hardy