How many bq are dangerous

The extent and time period of exposure to a dose is important to determine the likely biological damage to a human body. A healthy adult body has a given capacity to repair damage from radiation. Thus a full body exposure to a big dose over a short time is generally more harmful because the body cannot keep up with repairs, than a full body exposure to a small dose over a long time which the body usually can repair as it occurs.

Ingesting and inhaling radioactive particulate, such as radioactive dust blown by the wind from a nuclear plant fire or atomic bomb test, is harmful. As the radioactive particulate enters the cell, it damages the DNA which affects the expression of chromosomes which, in some cases, does not show up for decades as a tumor or cancer, making it difficult to establish cause and effect.

Exposure to other DNA-altering contaminants in the environment, such as urban pollution, lead from paints and gasoline, radon in stone buildings, herbicides, pesticides, industrial waste and agricultural run-off, and lifestyle exposures, such as from smoking, drugs, alcohol and pollutants in the workplace further complicates any cause and effect analyses. If a significant quantity of radioactive particulate stays in parts of the body, such as radioactive iodine in the thyroid or radioactive polonium in cigarette smoke in the lungs, it may cause DNA damage that leads to:.

As a significant part of the US soil, water, fauna includes people and flora was exposed to radioactive isotopes from atomic testing in Nevada, mostly during the 40s, 50s and 60s, adverse public health impacts, some lasting more than one generation, have occurred. Multiple-layer, aluminized suits with face masks and leaded-glass goggles provide skin protection against alpha and beta particles.

The addition of breathing filters provide protection against ingesting airborne, gamma-ray-emitting radionuclides; inhaling alpha and beta particles emitted by radionuclides and the associated gamma rays may cause cancer. Contaminated air filters need to be frequently replaced. There is no such portable protection against the gamma rays emitted from radio nuclides-contaminated surfaces and spilt liquids. Advising people to stay indoors is of marginal value, because houses have air leakage of about 1 to 4 air changes per hour ACH , depending on outdoor wind and temperature conditions; a minimum of 0.

There are three measurement units for radioactivity: the becquerel Bq measures radioactivity, the gray Gy measures the absorbed dose and the Sievert Sv measures the biological effects of the absorbed dose. The Bq measures the activity of the radioactive source, meaning the number of atoms which, within a particular time frame, transform and emit radiation. The Bq is a very small unit; multiples are often used:.

The radioactivity of an environment, a material or a foodstuff is given in Bq per kilogram or per liter. The Gy measures the absorbed dose, meaning the energy transferred by one or more isotopes to the material by ionizing radiation upon encountering it.

The Sv evaluates the effects of ionizing radiation on living material. At equal Gy doses, the effects of radioactivity on living tissue depends on the type and energy level of the radiation alpha, beta, gamma, neutron, etc. The Sv is a very large unit; sub-multiples are often used:.

There are several models to predict the long-term, biological damage caused by ionizing radiation. Three of them are discussed below.

The collection and analyses of data to validate one model over another is an ongoing process. Because the current data is inconclusive, scientists disagree on which method should be used. As noted above, any radiation dose needs to be adjusted with energy and tissue weighing factors and subjective factors, such as for a pregnant woman, to determine cancer risks.

Linear No Threshold Model: The linear no threshold model LNT is a method for predicting the long-term, biological damage caused by ionizing radiation and is based on the assumption that the risk is directly proportional to the dose at ALL dose levels, i. The LNT model does not hold for low-dose ionizing radiation, because a healthy body is able to repair the damage as it occurs. Only when the damage exceeds the repair capability will permanent damage occur.

Threshold Model: The threshold model assumes very small doses of ionizing radiation have negligible harmful effects below a certain threshold and do have harmful effects above it. The model is widely used in toxicology. The LNT model predicts higher cancer risks than the threshold model. Physicists and engineers have since adopted a more logical unit — the Becquerel — which corresponds to a decay rate of one per second.

The associated inconvenience, however, is that the Becquerel is a very small unit, adapted to the scales of the atom. Activities expressed in becquerels therefore lead to misleadingly large numbers, which can cause confusion among non-specialists.

For example, the human body has an activity of Bq — a value which may seem high but is in reality very small. It corresponds a few microcuries. Seeing activities written down in becquerels often gives the impression that such activities are exceptionally high and thus very dangerous. This is mainly due to the small value of a Becquerel, and substances are rarely that dangerous.

The Becquerel is like the Deutschmark used by the Weimar republic in the s when a wheelbarrow full of which was needed to buy a croissant. This is called the dose.

How ionising radiation is measured and defined has changed over the decades as we learn more about this relatively young science. Dose was originally measured in air by the unit of Roentgens R, named after the discoverer of X-rays, Wilhelm Roentgens. With the introduction of metric units the basic unit of absorbed dose became the Gray Gy , which represents an absorbed dose of 1 Joule of energy per kilogramme.

Unfortunately absorbed dose is not very convenient for radiological protection purposes because 1Gy of the different radiations - gamma and X-rays , beta particles , neutrons and alpha particles - is not equally damaging to tissue. Hybrid, because it is really not a unit of radiation dose but a unit of risk.

Thus, we talk of the equivalent dose of 1Sv as carrying the same risk, for example, as 1Gy for X and gamma rays, or 0. But there is a further complication, as not all tissues in the body are equally sensitive. So the term effective dose which incorporates the correction for equivalent dose and is also measured in Sv, is used. This way, if only part of the body is irradiated the risk can be presented in terms of an effective risk to the person.

This allows risks from different exposures to be added together. Effective dose is measured in sieverts Sv. Tissue weighting factors Table 4 represent relative sensitivity of organs for developing cancer.

In Canada, the Radiation Protection Regulations set radiation exposure limits for the public and nuclear energy workers.

The annual effective dose limit is 1mSv for the Canadian public. Based on information from regular monitoring of the most exposed workers, such as a radiographer, shows that the average annual doses are 5 mSv per year. The main ways to control radiation exposure include engineering controls, administrative controls and personal protective equipment.

Examples of these controls include:. Approximately forty-four 44 percent of monitored workers worldwide are exposed to artificial sources of radiation. Of those workers exposed to artificial sources, seventy-five percent work in the medical sector. Table 5 shows trends in global radiological exposure of workers since the s.

The effects of being exposed to large doses of radiation at one time acute exposure vary with the dose. Here are some examples:. In underground uranium mines, as well in some other mines, radiation exposure occurs mainly due to airborne radon gas and its solid short-lived decay products, called radon daughters or radon progeny.

Radon daughters enter the body with the inhaled air. The alpha particle dose to the lungs depends on the concentration of radon gas and radon daughters in the air. The concentration of radon daughters is measured in working level WL units this is a measure of the concentration of potential alpha particles per litre of air. Such estimates are subject to error because the ratio of radon to its decay products radon daughters is not constant.

Equilibrium factor is the ratio of the activity of all the short-lived radon daughters to the activity of the parent radon gas. Equilibrium factor is 1 when both are equal.

Radon daughter activities are usually less than the radon activity and hence the equilibrium factor is usually less than 1. Add a badge to your website or intranet so your workers can quickly find answers to their health and safety questions.