Interpreting Dangers of Radioactivity in Foods, Water and Objects

A recent analysis of an Amber Necklace at our sister site, Toxtest, for any emitting Gamma, Beta, Alpha Radiation revealed a level of 0.09 μSv per hour or, if worn 24/7, would equal about 788 μSv per year.

To put this into perspective, reports of average doses of radiation per year range from 3000 to 6000 μSv per year. This includes exposure from natural radiation (from soil, cosmic rays, etc.)  See below for informative charts.

Sv stands for Sievert. The μ stands for micro (one millionth) as opposed to m which stands for milli (one thousandth). The Sievert is used for radiation dose quantities such as equivalent dose and effective dose, which represent the risk of external radiation from sources outside the body, and committed dose which represents the risk of internal irradiation due to inhaled or ingested radioactive substances.
From https://en.wikipedia.org/wiki/Sievert  and https://www.cdc.gov/nceh/radiation/emergencies/measurement.htm

Note that 1 milli-Sieverts (mSv) is the same as 1000 micro-Sieverts (μSv). Alternatively, 1 micro-Sieverts (μSv) equals 0.001 milli-Sieverts (mSv). Sometime the radiation dose is shown in an older unit called the Rem or one thousandth of a Rem – the milliRem (mrem). If you need to convert then 1 mrem = 10 μSv.

At Toxtest, we measure radioactivity of objects like an Amber Necklace, using the Rotem RAM GENE-1 MARK II radiation counter that is able to measure Gamma, Beta, Alpha and X-ray radiation with a sensitivity range of 0.05 µSv/hr to 7000 µSv/hr. For liquids we use a Liquid Scintillation Counter that is able to achieve very low background counts. Cost of either test is $60.

Some exposure numbers to put things into perspective

Some people will say no amount of radiation is safe, but that doesn’t really help to understand the relative dangers. Here are some basic numbers to use as a guide:

• 8-15 μSv – The average radiation you receive daily
• 40 μSv – The radiation you receive by taking a flight from Sydney to Perth.
• 100 μSv – The radiation you receive during a dental x-ray
• 3,000 μSv – Radiation dose from a mammogram
• 3,600-6200 μSv – Average radiation a US citizen receives in a year from all sources
• 50,000 μSv – Maximum allowable yearly occupational dose (USA)
• 100,000 μSv – Lowest yearly dose likely linked to increased cancer risk
• 2,000,000 μSv – Severe radiation poisoning (sometimes fatal)

Note that On April 6, the radiation level in the city of Fukushima was 13.9 μSv/h.  If we multiply that number by the number of hours in a year, the yearly radiation dose is about 122,000 μSv.

This number is more concerning as the U.S. does not allow workers to receive more than 50,000 μSv per year at work. Compare this to the amount of radiation the astronauts (and you if you take an off-planet trip in the near future) receive – see table below – and note that numbers are in mSv.
From Radiation 101: What is it, how much is dangerous, and how does Fukushima compare to Chernobyl?

The Nuclear Regulatory Commission in the US helps us make sense of the different units used to measure radiation. The Sievert (Sv) (see-vert) is the unit for measuring ionizing radiation effective dose, which accounts for relative sensitivities of different tissues and organs exposed to radiation. The radiation quantity measured by the Sievert is called effective dose.

Radiation and Radioactivity

There are four different but interrelated units for measuring radioactivity, exposure, absorbed dose, and dose equivalent with both common (British, e.g., Ci) and international (metric, e.g., Bq) units in use:

• Radioactivity refers to the amount of ionizing radiation released by a material. Whether it emits alpha or beta particles, gamma rays, x-rays, or neutrons, a quantity of radioactive material is expressed in terms of its radioactivity(or simply its activity), which represents how many atoms in the material decay in a given time period. The units of measure for radioactivity are the curie (Ci) – older British system and becquerel (Bq) – the newer International system.
• Exposure describes the amount of radiation traveling through the air. Many radiation monitors measure exposure. The units for exposureare the roentgen (R) and coulomb/kilogram (C/kg).
• Absorbed dose describes the amount of radiation absorbed by an object or person (that is, the amount of energy that radioactive sources deposit in materials through which they pass). The units for absorbed doseare the radiation absorbed dose (rad) and gray (Gy).
• Dose equivalent (or effective dose) combines the amount of radiation absorbed and the medical effects of that type of radiation. For beta and gamma radiation, the dose equivalent is the same as the absorbed dose. By contrast, the dose equivalent is larger than the absorbed dose for alpha and neutron radiation, because these types of radiation are more damaging to the human body. Units for dose equivalentare the roentgen equivalent man (rem) and sievert (Sv), and biological dose equivalents are commonly measured in 1/1000th of a rem (known as a millirem or mrem).

Note that a measure given in Ci tells the radioactivity of a substance, while a measure in rem (or mrem) tells the amount of energy that a radioactive source deposits in living tissue. For example, a person would receive a dose equivalent of 1 mrem from any one of the following activities:

• 1 year of watching television (on average)
• 1 year of wearing a watch with a luminous dial
• 1 coast-to-coast airline flight
• 1 year living next door to a normally operating nuclear power plant

From – https://www.nrc.gov/about-nrc/radiation/health-effects/measuring-radiation.html
You can convert between radiation measures and unit at Unit Converter

Types of Radiation – Ionizing radiation

Ionizing radiation is radiation that has enough energy to remove electrons from atoms or molecules (groups of atoms) when it passes through or collides with some material. The loss of an electron with its negative charge causes the atom (or molecule) to become positively charged. The loss (or gain) of an electron is called ionization and a charged atom (or molecule) is called an ion.
Electromagnetic radiation – Examples: ultraviolet, visible light, x-rays, gamma rays. Particulate radiation – Examples:  alpha particles, beta particles, neutrons.

Artificial sources of radiation include X-ray machines, radioactive isotopes used in nuclear medicine, gamma cameras, nuclear gauges and nuclear power plants. X-rays refer to a kind of electromagnetic radiation generated when a strong electron beam bombards metal inside a glass tube. The frequency of this radiation is very high – 0.3 to 30 Ehz (exahertz or billion gigahertz). By comparison FM radio stations transmit at frequencies around 100 MHz (megahertz) or 0.1 Ghz (gigahertz).

Natural sources of radiation include: background radiation from space, cosmic radiation from cosmic rays, terrestrial radiation from minerals in the earth’s crust, radiation from inhaling radon gas, radiation from ingesting food and drinking water that may contain radioactive  potassium-40 and other radioactive elements like uranium and thorium.

Non-ionizing radiation

Radiation without sufficient energy to produce ionizations such as Microwave, infrared (IR) and ultra-violet (UV) radiation are examples of non-ionizing radiation. Non-ionizing radiation does not have enough energy to remove electrons.
From: https://www.ccohs.ca/oshanswers/phys_agents/ionizing.html

Further References:

• Typical doses and dose rates in studies pertinent to radiation risk inference at low doses and low dose rates
• What radionuclides can be found in food?
• BOOKLET to Provide Basic Information Regarding Health Effects of Radiation Vol.1 Basic Knowledge and Health Effects of Radiation
• Association between the detection rate of thyroid cancer and the external radiation dose-rate after the nuclear power plant accidents in Fukushima, Japan
• Biological Effects of Radiation