Radioactive Contamination in Consumer Products

Early this year the home retail chain Bed Bath & Beyond recalled over 200 shipments of a brushed steel tissue box holder.  The stir caused by the recall inspired great headlines like this one from Gizmodo¹:

Time to decorate! I'll take this potpourri urn, these palm frond bookends, a nice neutral-colored bathmat, and WHY IS THIS TISSUE BOX EMITTING DANGEROUS RADIATION?!!

The recalled tissue box from Bed Bath & Beyond. source

In reality, radiation contamination in consumer products is no laughing matter, and this is no isolated case.  Contaminated consumer products have been traded between many countries, and a wide range of products have been identified. 

In 2009, Wal-Mart was fined almost $400,000 by the Nuclear Regulatory Committee for exit signs containing radioactive material².  500 sets of radioactive elevator buttons were found in France in 2008³. A few cheese graters turned up in Michigan containing cobalt-60, the same isotope found in the Bed Bath & Beyond’s tissue box holders. Even a batch of 1000 La-Z-Boy recliners was found to have radioactive metal brackets in 1998⁴.  Due to the common occurrence of radiation in consumer products, the US government even set up a Nuclear Material Events Database in 1990.  Since then over 20,000 cases of radiation releases have been documented⁵.

The additional radiation exposure to consumers of these products is generally low level but still a cause for concern.  The tissue boxes were estimated to expose consumers using bathrooms with the boxes to the equivalent of a few extra chest x-rays per year.  Unexpected radiation sources add up: chronic exposure of even low doses of radiation can lead to cataracts, cancer and birth defects, according to the U.S. Environmental Protection Agency. A 2005 study of more than 6,000 Taiwanese who lived in apartments built with radioactive reinforcing steel from 1983 to 2005 showed a statistically significant increase in leukemia and breast cancer ⁶.

The question remains: if we don’t carry a radiation detector with us every time we go shopping, how will we know which products to avoid?  The solution has to involve better detection along increasingly complex supply chains.  Most of the tainted metal introduced into consumer products comes from contaminated batches of scrap metal, sometimes containing radiation acquired in nuclear power activities.  As this metal travels is formed, shaped, and implemented in products, too few check points are involved to catch radiation.  Radiation detectors need to become part of the manufacturing process, not just a safeguard against large foreign radiation sources.  And due to the wide range of consumer products tainted by radioactive materials, detectors need to screen more products. 

With new guideless and increased detection during manufacturing and distribution, we can finally be confident that our next hot buy won’t really be hot.

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D-tect Systems is a supplier of advanced radiation and chemical detection equipment sold around the world. www.dtectsystems.com.

1.      http://gizmodo.com/5875898/bed-bath--beyond-caught-selling-radioactive-tissue-boxes

2.      http://pbadupws.nrc.gov/docs/ML0930/ML093050018.pdf

3.      http://articles.latimes.com/2008/nov/12/business/fi-radioactive12

4.      http://nmed.inl.gov/AnnualReports/NMEDFY10%20Annual.pdf

5.      http://public.shns.com/node/43582

6.      http://www.businessweek.com/news/2012-03-19/nuclear-risks-at-bed-bath-and-beyond-show-hidden-danger-of-scrap

Relative Biological Effectiveness - What Kind of Radiation is the Most Risky?

As you read this right now, you are being bombarded by radiation – cosmic rays flying in from the dark reaches of space, photons streaming out of the hot core of the earth, and miniscule particles issuing from your computer and other objects around you. But not all radiation is created equal. A new field of study has unearthed the fact that different kinds of radiation affect us differently.  

Although quite a mouthful, this study is called Relative Biological Effectiveness (abbreviated RBE). It seeks to put all radiation on an equal plane and find out what kind poses the highest risk to our organism. Higher values of RBE mean that certain types of radiation are more harmful. Ionizing radiation, which is made up of alpha, beta, and gamma rays, constitute electrically charged particles that interact with matter. These interactions can cause ionization, which refers to changes within the structure of an atom that can cause it to destabilize or behave differently.

Alpha particles are the largest kind of ionizing radiation, each consisting of two protons and two neutrons. Because they are highly charged and quite large, they are quickly stopped by as little as 4 cm (1.4 inches) of open air or a sheet of paper¹. Beta particles are much smaller, meaning they can penetrate further: through 9 meters (19 ft) of open air or 11 mm (.4 inches) of body tissue. Gamma rays are high-energy photons, meaning that they penetrate much further and interact differently with matter than alpha or beta particles. Thick, dense materials such as lead are necessary to block gamma rays. Another related form of radiation is neutron radiation, which is commonly referred to as indirectly ionizing radiation. Free neutrons, which are emitted from nuclear materials such as uranium and plutonium, have about a quarter of the mass of an alpha particle². Neutrons are not charged but readily cause ionization by knocking away electrons or slamming into atomic nuclei. The neutral charge of these fast-traveling neutrons also allows them to penetrate much further into most materials than other types of ionizing radiation, even through many feet of concrete.

Source: American Nuclear Society

 To test how damaging different types of radiation is on the human body, scientists expose living tissue to equal amounts of energy from each type. Surprisingly enough, scientists have found that beta and gamma radiation are nearly equally damaging, so the RBE value of beta and gamma radiation is 1. It gets more complicated from here, though. Alpha and neutron radiation have different RBE values depending on what kind of cells are exposed to them. The RBE for bacteria is 2-3, but can be 6-8 for more complex cells like those found in the human body. This means that a certain amount of alpha radiation is 6-8 times more damaging then the same amount of beta radiation. Neutrons are even more damaging with a RBE of 4-6 for bacteria and 12-16 for complex cells³.  

The high RBE values of alpha and neutron radiation should make us think twice about how we deal with these types. Because incoming alpha particles are stopped by a single layer of skin, they can’t do much damage unless they get in our bodies. That’s why breathing in alpha radiation (from radon or radioactive dust) or ingesting it (in contaminated food or water) is so dangerous. When alpha particles get to really important cells in our organs, the RBE can shoot up: scientists have measured RBE values of 1,000 for alpha radiation inside hamsters⁴. Neutron RBE values are more constant because neutrons penetrate just about everything, but they are also much harder to contain. That’s why materials that emit neutrons are highly controlled, very hard to transport, and large neutron sources are only found in research facilities and power plants.

The Rad-ID device by D-tect Systems has a special way of finding neutron radiation. A container filled with Helium-3, a rare and stable gas, is included with other radiation detectors inside the Rad-ID. As neutrons shoot through the detector, they collide with some of the He-3 atoms, causing them to change into charged particles. These particles are quickly identified and counted by a detector and a measurement of this radiation is sent to the user. Since neutron sources give off varying levels of gamma radiation, the Rad-ID can also identify these materials and let the user know what they are dealing with.

The Rad-ID can detect neutron radiation sources.

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D-tect Systems is a supplier of advanced radiation and chemical detection equipment sold around the world. www.dtectsystems.com.

  

Radon: Radiation on the Home Front

It seeps up through the ground, pooling in basements and cellars. It can infiltrate our homes and even our lungs, spreading radiation with every ripple of breeze. Present in nearly every country of the world, this substance is colorless, odorless, and tasteless. It kills thousands every year and requires special equipment to locate.

Although this sounds like something from a cheesy science fiction film, radon gas is a real threat to people all over the world. Radon-related diseases cause about 21,000 deaths per year in the US¹ (almost twice the number of drunk driving deaths), meaning in most countries only smoking causes more deaths from lung disease.

Deaths Per Year - Source: http://www.epa.gov/radon/pubs/citguide.html

The first reason radon is dangerous is because it’s all around us. The EPA estimates that 1 out of every 15 homes in the US has elevated radon levels² . In almost every country radon is the largest natural source of human exposure to ionizing radiation and makes up over half the radiation each person is exposed to in a year. Since radon is a decay product of uranium, it is more often found where there are large concentrations of granite, like those occurring in Ireland and the UK, Canada, and some US states such as Iowa and Pennsylvania.  

Radon Test Kit - Source: http://visualsonline.cancer.gov

The physical properties of radon also contribute to its effect on people.  Radon is one of the most dense gases on our planet – over 8 times denser than the atmosphere at sea level. This causes it to pool at the bottom of whatever container it is in. Because of this, elevated radiation levels from radon are found in the lower levels and basements of buildings. It also means that when breathed in, radon gets trapped in the bottom of the lungs and has more potential to do damage. Radon emits mostly alpha radiation which is made up of fast-moving particles with more mass than beta or gamma radiation. Alpha radiation doesn’t penetrate very well – it can be stopped by as little as a piece of paper or human skin. So the real risk to humans from alpha radiation is when it gets inside us and starts to affect our internal organs. Because it is a gas, almost all the damage done is in the lungs and can lead to lung cancer.   

The good news about radon is that it is easily detectable and many options are available to lessen radon risks in the home. Short- and long-term radon test kits are inexpensive and commercially available throughout the world. A short-term test (which takes several days) gives the homeowner an estimate of radon concentration in the home, and a subsequent long-term test (which takes a year or more) can give a more precise measurement. There are varying ‘action levels’ of radon throughout the world, but most countries recommend taking some action to reduce radon if average concentrations are above 4 pCi per liter of air³. Solutions to lower radon concentrations include venting air from lower stories of a house or pressurizing areas to keep external gases out.

An example of radon venting from the US EPA.

Although radon may sound scary and looks pretty bad on paper, many people can significantly lower their risk of radiation exposure from radon. Good information is widely available on this subject, including the World Health Organization’s Radon Handbook and A Citizen’s Guide to Radon by the US Environmental Protection Agency.  

1) http://www.epa.gov/radon/pubs/citguide.html

2) http://www.epa.gov/radon/pubs/citguide.html

3) http://www.who.int/mediacentre/factsheets/fs291/en/index.html

D-tect Systems is supplier of advanced radiation and chemical detection equipment sold around the world. www.dtectsystems.com.

Radiation Challenges Continue in Fukushima

Even though media coverage of the Japanese nuclear crisis has decline rapidly following the first few weeks of the disaster, there is still a steady stream of cleanup updates and survivor stories hitting international media outlets. Many of these have to do with the residents of the Fukushima Prefecture, whose proximity to the stricken nuclear complex has made life extremely difficult. Changing government regulations, delayed cleanup efforts, and a lack of scientific understanding of the whole situation has added to the chaos of the situation.

A common theme in many of these recent stories is the risk of radiation exposure to children living in or near the prefecture. Although the 20 kilometer evacuation zone set by the Japanese government has helped limit the radiation exposure to many people, there is no guarantee of safety even outside this radius. The problem is that radiation given off by the nuclear plant is extremely hard to track: wind- and water-borne radioactive particles have settled in unpredictable hotpots across the prefecture. This is a major concern for the more than 300,000 residents living in Fukushima city, parts of which lie inside the evacuation zone.

A local Japanese man checking the exterior of a church with the MiniRad-D.

A recent article by the International Herald Tribune reports that more than 70 elementary and secondary schools are located within the city where radiation levels have been measured above the safe dose level for nuclear plant workers – which is much higher than what is safe for children. Many of these schools have no way to monitor changing radiation levels and have received no help from the government to decontaminate school grounds. This has many parents worried and angry at the Japanese government, and a few have already taken the problem into their own hands. One day care center measured a drop in radiation levels from 30 times to two times the background level after volunteers scraped off the top layer of dirt on the playground. Efforts are underway at other schools to remove contaminated soil and plants from school property.

A MiniRad-D showing the radiation reading in a Japanese courtyard.

We are also committed to help out these children. In two separate trips to Japan since the crisis began, we’ve been able to see for ourselves what the situation is like. Members of our team have been working with charitable organizations to scan schools and churches for radiation and we’ve donated ten MiniRad-D units (pager-sized radiation detectors) to help school district officials determine safe and unsafe levels of radiation so parents feel comfortable about sending kids to school. These units are also used to help churches determine radiation levels at their buildings. Check out this post for details of the first trip.

Although the media coverage has mostly moved on to newer stories, the Japanese nuclear crisis is far from over. A tremendous amount of work remains before the Japanese confidence, economy, and environment completely stabilizes. 

 

D-tect Systems is supplier of advanced radiation and chemical detection equipment sold around the world. www.dtectsystems.com.

Putting Radiation in Perspective

Due to the recent nuclear crisis in Japan, we've seen much more technical jargon than usual on major news stories. A reason for this is that radiation physics is a highly technical field and even quantifying radiation can be very complicated: a shift of a few decimal places can mean the difference between no risk and a major radiological hazard. Even the units are new - how many people have ever used 'becquerel' or 'half-life' in a casual conversation?

In conjunction of the new language hitting newspapers and TV screens, we've seen a great push to put radiation in perspective. This basic education goes a long way to help people make choices on how much they should worry about what is going on in Japan and what they can do to protect themselves. Visual examples are popular such as this one on xkcd.com, as well as thorough explanations discussed here by Harvard Medical School.

In supporting this movement, we recently released a Radiation Basics Sheet that we put together with data from the World Nuclear Association and US Environmental Protection Agency. We included some relative doses such as how much radiation you'll get from watching a year of TV, how much from a chest x-ray, and how much you'll get from flying across the US. We hope that this information can be used to turn dispel fears and boost confidence. 

Our sheet was recently featured on the blog of STORMWATER (a journal for surface water quality professionals). The post What do the Numbers Actually Mean? is very informative and talks about radiation contamination in Tokyo's tap water. We're excited that someone is putting this information to good use, and we're grateful to STORMWATER for the coverage.

If you would like more information to help you put radiation risks in perspective, we here at D-tect Systems have experts in the radiation detection field who can provide more information by email (info@dtectsystems.com) or even on the phone (801.495.2310). 

D-tect Systems is supplier of advanced radiation and chemical detection equipment sold around the world. www.dtectsystems.com.

Radiation Contamination in Food and Water: What's the Risk?

As Japanese emergency workers continue to pump out thousands of gallons of contaminated water from the damaged reactors of the Fukushima Power Plant, radiation contamination in food and water has emerged as a new focus of the international media.  

Before explaining the risks of food and water contamination, it’s important to understand the difference between radiation exposure and radiation contamination.  The United States Center for Disease Control (CDC) defines exposure and contamination with the following:

A person exposed to radiation is not necessarily contaminated with radioactive material. A person who has been exposed to radiation has had radioactive waves or particles penetrate the body, like having an x-ray. For a person to be contaminated, radioactive material must be on or inside of his or her body. A contaminated person is exposed to radiation released by the radioactive material on or inside the body. An uncontaminated person can be exposed by being too close to radioactive material or a contaminated person, place, or thing.”

Source: U.S. Department of Health

As the CDC implies, there are many ways that radiation can enter the body for contamination to occur.  Radioactive materials that enter into digestive tract can do damage while they reside in the body, but most of these materials pass through quickly. Radiation that gets trapped in other areas of the body, such as radioactive dust being breathed in and lodged in the lungs, can cause serious threats because the longer the radiation resides in the body, the more harm it can do.

So what are levels of radiation we actually need to worry about in food or water? The unit of measurement used for quantifying radiation in food and water is the Becquerel (Bq) and defined as the activity of a radioactive material in which one nucleus decays per second. More dangerous sources of radiation give off higher readings, and amounts decrease as radioactive isotopes decay. The Becquerel is a very small quantity of radiation; the human body itself produces over 4000 Bq per second. The standards set by the United States Food and Drug Administration (FDA) for food and water is about 375 Bq/lb (170 Bq/kg).

Recently Japan reported a reading of 463 Bq/lb (210 Bq/kg) in Tokyo’s tap water, leading to widespread fear and a government advisory against giving tap water to children (who are more susceptible to radiation and have lower exposure limits). Since this incident, the radiation in Tokyo’s tap water has returned to safe limits. Radiation in food has also been a problem, especially since much of the Fukushima Prefecture near the crippled nuclear plant is dedicated farmland.  Widespread bans have gone into place on the sale and consumption of crops from affected areas, as well as seafood caught in the ocean near the plant. Much of the radiation present in the contaminated food and water is Iodine-131, which has a half-life (meaning that half of a quantity of the material has broken down and is not longer radioactive) of only 8 days. This means that this type of radiation won’t be around for long, but the fear of radiation is more likely to hurt the Japanese economy as buyers shy away from food that they think might still have some contamination.

Source: Associated Press

Although the fear that Japanese radiation in dangerous amounts will end up in other countries is often unfounded, we can’t let down our guard just yet. Japan provides 4% of US food imports, including many seafood products that can have concentrated levels of radiation, such as shellfish and seaweed.

So how can we assure that our food and water is contamination free? Finding trace amounts of radiation in food and water is often difficult because products are usually shipped in large containers that shield radiation. Common radiation detectors such as Geiger Counters just aren’t sensitive enough to detect radiation at these levels. The FDA works to safeguard our food supply by using the MiniRad-D, a hand-held radiation detector, to search for radiation. The MiniRad-D uses a scintillation detector, which is over 100 times more sensitive than a Geiger counter, and because it can pick up radiation from tens of meters away, it can be used to scan whole containers of food at once. 

The MiniRad-D radiation detector

The procedure of scanning food is becoming increasing popular as Japan increases its exports. According to a recent New York Times article, even some fish markets and high-end restaurants have begun radiation detection procedures to ensure the safety of their customers. Knowing for sure that food and water is clean is a big draw for these businesses as Japan’s nuclear clean-up continues to make headlines.

So, although the direct danger of radiation contamination in food and water is very low, the effects of the nuclear crisis are sure to be felt for years to come. And as many companies involved with food imports are discovering, peace of mind is not only attainable, but extremely valuable. With the right equipment, good information, and correct procedures, this peace of mind is truly available to everyone.

D-tect Systems is supplier of advanced radiation and chemical detection equipment sold around the world. www.dtectsystems.com.

 

Radiation Basics Sheet

A pdf version of this document can be found on the D-tect Systems website, here.

Background radiation: ~ 3 mSv/yr (300 mrem/yr) in North America and slightly higher in Asia. 88% of background radiation comes from natural sources (half of this from radon gas), almost all the remaining radiation comes from medical sources.

World Nuclear Organization

Safety Levels: American regulatory limit for occupational exposure: 50 mSv/yr (5 rem/yr). This limit was chosen because it is the lowest rate at which there is evidence of cancer being caused in adults. Pregnant women and children should have no more than a 10^th of this (5 mSv/yr or 500 mrem/yr). A lethal full-body dose for a man is around 4-5 Sv (400-500 rem) in a short time period.

Radiation Sickness Threshold: 1000 mSv (1 Sv or 100 rem) in a short time period. Symptoms: nausea, hair loss, weakness, skin burns

Long-term Radiation Exposure: cancer, cell mutation, birth defects.  The danger of continued overexposure to radiation is that symptoms can appear after 20 years after exposure.

Radiation Exposure vs. Distance: if you double the distance, you reduce the exposure by a factor of 4.

Ionizing Radiation Types

Alpha

Penetration: stopped by skin or paper, dangerous when ingested or breathed in.

Beta

Penetration: stopped by aluminum plate or 1 cm of human flesh, heavy clothing may be needed.

Gamma & X-rays

Penetration: easily passes through most matter, shielding requires concrete, lead or water.

Neutron

Penetration:  Just like gamma rays, shielding requires concrete or water.  Neutron radiation only comes from cosmic rays and nuclear reactions, and although it isn’t ionizing, it can cause other materials to become radioactive and is often accompanied by other radioactive materials.

Protection from Radiation

Limiting Time: For people who are exposed to radiation in addition to natural background radiation through their work, the dose is reduced by limiting exposure time.

Distance: In the same way that heat from a fire is less the further away you are, the intensity of radiation decreases with distance from its source.

Shielding: Barriers of lead, concrete or water give good protection from penetrating radiation such as gamma rays. Radioactive materials are therefore often stored or handled under water, or by remote control in rooms constructed of thick concrete or even lined with lead.

Containment: Radioactive materials are confined and kept out of the environment. Radioactive isotopes for medical use, for example, are dispensed in closed handling facilities, while nuclear reactors operate within closed systems with multiple barriers which keep the radioactive materials contained. Rooms have a reduced air pressure so that any leaks occur into the room and not out from the room.

Radiation Exposure Units of Measurement

Exposure: measure of the strength of a radiation field at some point in air.  Basic unit: “roentgen” (R).

Dose: absorbed dose is the amount of energy that ionizing radiation imparts to a given mass of matter.  Basic units: “gray” (Gy) and “radiation absorbed dose” (rad). 1 Gy = 100 rads.  In human tissue, 1 R of gamma radiation = 1 rad of absorbed dose.

Dose Equivalent: relates to the absorbed dose to the biological effects of that dose. Basic units: “sievert” (Sv) and “roentgen equivalent in man” (rem). 1 Sv = 100 rem.

Dose Rate: a measure of how fast radiation a radiation dose is being received.  Basic units: mSv/yr, mrem/yr, etc.

Half-life: The time it takes for half the nuclei in a specific isotope to undergo decay.

Radiation Examples

Air travel: measured dose during air travel is 5 µSv/hr (43.8 mSv/yr or 4380 mrem/yr) according to the FAA.  This is about 15 times background radiation.

Watching TV: 4 hours a day adds up to 2 mSv/yr (200 mrem/yr)

Allowable short-term dose for workers on the Fukushima accident: 250 mSv (25 rem)

Radiation Measurement on the perimeter of the Fukushima Nuclear Plant: 1-3 mR/h (about 10-30 µSv/h)

U.S. Environmental Protection Agency

Atomic Shorthand

Example: “Iodine-131” = ₅₃I¹³¹

Radioactive Iodine

Iodine concentrates in the thyroid. Because of this, radioactive iodine (a byproduct of nuclear reactions) contributes to thyroid cancer more than other types of cancer. For this reason, potassium iodide tablets are given to increase the amount of safe iodine in the body, as this limits the amount of radioactive iodine the body will absorb.

The most common kind of radioactive iodine (Iodine-131) has a half-life of only 8 days.

Nuclear Plants

There are over 440 commercial nuclear power plants operating in 30 countries which accounts for about 14% of the world’s power.  The US has 104 operating reactors, the most of any nation.  Japan previously had 56.

International Atomic Energy Agency

Alarm Levels for the MiniRad-D Radiation Detector

Alarm Level	µrem/hr	mrem/hr	µSv/hr	mSv/hr
1	35	0.035	0.35	0.00035
2	40	0.04	0.4	0.0004
3	55	0.055	0.55	0.00055
4	65	0.065	0.65	0.00065
5	100	0.1	1	0.001
6	200	0.2	2	0.002
7	350	0.35	3.5	0.0035
8	600	0.6	6	0.006
9	1100	1.1	11	0.011

D-tect Systems

 The radiation facts and protection information in this post were published by the World Nuclear Association and health information was published by the US Environmental Protection Agency.