How can you measure radon in water?

Transcription

1 Lesson 9: How can you measure radon in water? Lesson overview This lesson explains approved techniques to measure radon in water. Lesson objectives By the end of this lesson, the learners will be able to: Name the health problems associated with radon in water Describe approved techniques for measuring radon in water In this lesson, we are going to talk about techniques of measuring radon in water. See slide 9 1. For most of this training, we have focused on radon in the air. However, we did mention earlier that radon in the tap water may also be a problem. Not all tap water contains radon. If the tap water comes from a surface water source, such as a river, lake, or reservoir, most of the radon in the water is released into the air before it can reach a water supply company or a home. As a result, surface water, such as in lakes and streams, usually has a low radon concentration. If the tap water comes from underground, such as a well that pumps water from an aquifer, it may be a concern. However, not all water from underground sources contains radon. The average concentration of radon in public water supplies that come from groundwater sources is about 540 pci/l. In comparison, some wells have concentrations over 200,000 pci/l. And radon levels in New England are, on average, higher than levels in many other parts of the United States. Like air, water must be tested to determine whether it contains radon and, if so, how much. See slide 9 2. Lesson 9 1

2 If the water does contain radon, the risk comes both from radon that water releases into the air and from radon that remains in the water. Water releases radon into the air through such activities as showering, dishwashing, flushing a toilet, cooking, and doing laundry. Warm, actively moving water releases more radon than cold, still water. It takes high levels of radon in water to significantly raise the levels of radon in the air for two reasons: Only some of the radon from the water transfers to the air. The relatively small volume of water from normal use is diluted by the large volume of air in the home. On average, if the home water supply contains 10,000 pci/l, normal use will raise the radon in the air by about 1 pci/l. Nonetheless, although only a small percentage of the radon in the air comes from tap water, that amount adds to radon from other sources. And in some areas where people use a lot of hot water, such as bathrooms and laundry rooms, the radon levels can get especially high. Breathing that radon increases the risk of lung cancer over the course of a lifetime. Radon that remains in the water also represents a risk, although a smaller one. Drinking water that contains radon increases the risk of developing cancer in the stomach, as well as in other internal organs as the radon is absorbed into the blood. See slide 9 3. The Environmental Protection Agency estimates that radon in drinking water causes about 168 cancer deaths per year. Of those deaths 89 percent are from lung cancer caused by breathing radon released into the air from water o As with radon in the air, smoking increases the risk of lung cancer from radon in the water 11 percent are from stomach cancer caused by drinking water that contains radon. The EPA does not currently have a maximum contaminant level (MCL) for radon in water, as it does for other substances that are known to cause cancer. In 1996, amendments to the Safe Drinking Water Act required EPA to establish new, health based drinking water regulations for radon in public water systems. EPA proposed Lesson 9 2

3 a standard of 300 pci/l in 1999, but that rule is still not final and it does not cover private wells. See slide 9 4. However, the Connecticut Department of Public Health (DPH) recommends that homeowners served by private wells consider treatment if their average annual radon in water is 5,000 pci/l or more. The average is determined by two or more samples in one year. Once EPA has issued a regulatory standard for radon in water, DPH will consider adopting the standard for private wells in Connecticut. See slide 9 5. See the Connecticut Department of Public Health s list of laboratories approved to analyze radon in water (download current list from LABLIST.pdf. There are two important principles for taking a water sample for radon: 1. Sample carefully You must sample fresh water directly from well, not from holding tanks or plumbing Avoid exposing the sample to open air when you collect and transport it. Because radon is a gas, exposure to air may lead to loss of some gas and inaccurate measurement. Avoid bubbles in the sample vial. 2. Make sure that a lab analyzes the sample within 4 6 hours of the time of collection. Use a lab approved by the Connecticut Department of Public Health (see BRS/EHS/Radon/Documents/LABLIST.pdf Approved labs use the liquid scintillation counting method to analyze radon in water See slide 9 6. Two basic sampling techniques are used: Syringe technique Immersion technique See slide 9 7 Lesson 9 3

4 For both techniques, simple preparation is required to make sure that you sample directly from the well, not from holding tanks or plumbing. Remove aerator if present Select a sample point before water passes through any water treatment device Example: Outside hose connection Purge water that has been sitting in pipes and tanks Run cold water from faucet for enough time to collect water directly from the well Usually about minutes If sampling outside Do not let purge water puddle in the yard Resident can assist purging by running water inside the home Sample before Hot water heater Water softener Holding tank See slide 9 8. With the syringe technique, you need the following equipment: A 20 ml hypodermic syringe 2 glass vials With TFE or foil lined caps that seal tightly Containing liquid scintillation cocktail A sampling funnel Tubing or hose See slide 9 9. Use a short hose to connect the funnel to faucet Run water to fill the hose and overflow funnel Slow the water flow and insert syringe below water surface in funnel Slowly collect a ml sample Rinse and repeat a few times Invert syringe to eject any air bubbles and retain 10 ml of water Place syringe tip below liquid scintillation cocktail and gently inject 10 ml sample into vial Slowly withdraw syringe Tightly cap the vial Repeat, taking second sample from same source Lesson 9 4

5 See slide The immersion technique requires the following equipment: 2 40 ml glass vials with TFE or foil lined caps that seal tightly Hose or tubing Clean 5 gallon bucket or similar container See slide Attach one end of hose or tubing to spigot, and place other end in bucket Fill bucket about half full of water Slow the flow rate and submerge vial in bucket Place vial below hose, where fresh water is entering bucket Let vial fill with fresh water for about 20 seconds Cap vial while it is still submerged and water is running Repeat with another vial, taking second sample from same source Be very careful to avoid air bubbles. See slide After you have collected two vials: Check both vials for air bubbles. o Turn vials upside down. o If you see bubbles, repeat the collection procedure until you get a sample that contains no bubbles. Record the sample name/id (usually the address), and the date, and time of collection. Pack vials carefully. Mail to lab the same day. o Send via quick method so sample arrives within 3 days. The lab should analyze the sample the same day it arrives. See slide See Handout 9 1, which summarizes the techniques and procedures for collecting water samples. See slide In this lesson, we talked about measuring radon in water. Lesson 9 5

6 We noted that water from underground sources may contain dangerous levels of radon, which can cause cancer of the lungs, stomach, and other organs. We explained that the Connecticut Department of Public Health guidelines suggest that owners of private wells with an average level of 5,000 pci/l or more should mitigate to reduce their exposure to radon. See slide Consider. We emphasized two principles of taking water samples. Do you remember what they were? Correct answers: 1. Sample carefully to obtain water directly from the well and avoid exposing the sample to air. 2. Analyze the samples promptly. See slide Finally, we discussed two techniques of sampling syringe and immersion and the associated procedures. See slide Consider. Do you have any questions about sampling water? See slide Check comprehension. See Handout 9 2A. This comprehension check is not graded. Now you re going to see whether you remember the main points that we ve discussed in this lesson. Please answer the questions on handout 9 2A. When you all finish, we ll review the answers together. See Handout 9 2B, the answer key. Review the answers. The key information in lesson has already been summarized on handout 9 1, so there is no lesson summary sheet. Lesson 9 6

7 Resources National Academy of Sciences, Commission on Life Sciences Risk Assessment of Radon in Drinking Water. National Academies Press. Accessed July 5, University of Illinois at Chicago, Great Lakes Centers for Occupational and Environmental Safety and Health, Radon Course on Measurement. Accessed July 6, Lesson 9 7

8 Handout 9 1: Collecting water samples Preparation: to make sure that you sample directly from the well, not from holding tanks or plumbing. Remove aerator if present Select a sample point before water passes through any water treatment device Example: Outside hose connection Purge water that has been sitting in pipes and tanks Run cold water from faucet for enough time to collect water directly from the well Usually about minutes If sampling outside Do not let purge water puddle in the yard Resident can assist purging by running water inside the home Sampling techniques Syringe technique Equipment A 20 ml hypodermic syringe 2 glass vials With TFE or foil lined caps that seal tightly Containing liquid scintillation cocktail A sampling funnel Tubing or hose Procedure Use a short hose to connect the funnel to faucet Run water to fill the hose and overflow funnel Slow the water flow and insert syringe below water surface in funnel Slowly collect a ml sample Rinse and repeat a few times Invert syringe to eject any air bubbles and retain 10 ml of water Place syringe tip below liquid scintillation cocktail and gently inject 10 ml sample into vial Slowly withdraw syringe Tightly cap the vial Repeat, taking second sample from same source Immersion technique 2 40 ml glass vials with TFE or foil lined caps that seal tightly Hose or tubing Clean 5 gallon bucket or similar container Be careful to avoid air bubbles Attach one end of hose or tubing to spigot, and place other end in bucket Fill bucket about half full of water Slow the flow rate and submerge vial in bucket Place vial below hose, where fresh water is entering bucket Let vial fill with fresh water for about 20 seconds Cap vial while it is still submerged and water is running Repeat with another vial, taking second sample from same source Lesson 9 8

9 After collection Check both vials for air bubbles. o Turn vials upside down. o If you see bubbles, repeat the collection procedure until you get a sample that contains no bubbles. Record sample name/id (usually address), and date and time of collection Pack vials carefully Mail to lab the same day o Send via quick method so sample arrives within 3 days The lab should analyze the sample the same day it arrives Lesson 9 9

10 Handout 9 2A: Check your understanding Select the best answer from the choices below. Circle the correct answer. 1. The risk from radon in water comes from a. Radon released into the air and radon remaining in the water b. Only radon released into the air c. Only radon remaining in the water d. Radon in the shower 2. Radon in water causes a. Bone cancer and brain cancer b. Arthritis and earaches c. Asthma and stomachaches d. Lung and stomach cancer 3. The Connecticut Department of Public Health recommends that, for private wells, owners mitigate if average radon levels are a. 5 pci/l or more b. 500 pci/l or more c. 5,000 pci/l or more d. 15,000 pci/l or more 4. Which of the following is not a principle of sampling water? a. Aerate samples thoroughly before sending to a lab b. Sample fresh water directly from the well c. Avoid exposing the sample to air d. Make sure that sample is analyzed promptly 5. Which of the following steps is part of preparing to take a water sample? a. Install aerator if none is present b. Select a sample point after water heater c. Run hot water until it reaches its maximum temperature d. Run cold water until you are collecting water directly from the well 6. In the syringe technique, use glass vials containing a. Solid scintillation cocktail b. Liquid scintillation cocktail c. Uranium cocktail d. Liquid lead 7. Which of the following indicates a problem with a water sample? a. Charcoal particles in the water b. Air bubbles c. Soap bubbles d. Dead fish Lesson 9 10

11 Handout 9 2B: Check your understanding Answer key The correct answers are shown in bold. 1. The risk from radon in water comes from a. Radon released into the air and radon remaining in the water b. Only radon released into the air c. Only radon remaining in the water d. Radon in the shower 2. Radon in water causes a. Bone cancer and brain cancer b. Arthritis and earaches c. Asthma and stomachaches d. Lung and stomach cancer 3. The Connecticut Department of Public Health recommends that, for private wells, owners mitigate if average radon levels are a. 5 pci/l or more b. 500 pci/l or more c. 5,000 pci/l or more d. 15,000 pci/l or more 4. Which of the following is not a principle of sampling water? a. Aerate samples thoroughly before sending to a lab b. Sample fresh water directly from the well c. Avoid exposing the sample to air d. Make sure that sample is analyzed promptly 5. Which of the following steps is part of preparing to take a water sample? a. Install aerator if none is present b. Select a sample point after water heater c. Run hot water until it reaches its maximum temperature d. Run cold water until you are collecting water directly from the well 6. In the syringe technique, use glass vials containing a. Solid scintillation cocktail b. Liquid scintillation cocktail c. Uranium cocktail d. Liquid lead 7. Which of the following indicates a problem with a water sample? a. Charcoal particles in the water b. Air bubbles c. Soap bubbles d. Dead fish Lesson 9 11