Study of Lung Cancer Hazard Due to Radiate Radon Gas for Two Factories in Industrial Region (Shaikh Omar) of Baghdad Governorate

During the winter, in the industry region (Shaikh Omer) and by applying a passive radon detector (CR-39), lung cancer risk has been measured in twelve rooms of different workshops of two old factories in this site. The radon concentration is ranged from (123.345 Bq/m3) to (328.985 Bq/m3) with an average of (244.19±61.52 Bq/m3). Lung cancer risk ranged from 55.993 to 149.346 per million people and with an average of (110.855 per million people) which were lower than the recommended values (170-230 per million people), so there was no cancer risk on workers in these locations. Keyword: Radon decay, radon risk parameters, Shaikh Omer region.


Introduction
Radon is found in all types of soils and rocks in concentration that varies from region to region and during the seasons. when gas is sent out from the soil, it spreads in the open air at small speed and safe due to its half-life. Once it infiltrates into closed places,it can pile, and reach to dangerous levels relying on its concentration in soil, buildings materials. It can enter the buildings through groundwater or from the building materials that have Radium [1].when the radiation enters the lung, it decays inside it, which is the subject? save for a few amounts transported by blood. The risk of radon begins from the fact that when it decays, that it's solid decays products settle in the airways and inner surfaces of the lung. The decays products of radon are polonium ( 218 Po), half-life (t1/2 = 3.05 min), which end with the lead ( 214 Pb), halflife (t1/2 = 26.8 min), then Bismuth ( 214 Bi) the half-life of it (t1/2= 19.7 min) down to polonium ( 214 Po)which has half-life (t1/2= 162μs). Two of these products are emitters of alpha particles ( 218 Po emitter alpha at energy 6MeV and 214 Po emitter alpha at energy 7.69MeV), which are the main source of harmful radiation if they stabilize within the lung[2].The danger of lung cancer from exposure of the Radon and its decay outputs depend on their concentration level in the home; also the extent of time that a person ;is exposed to Radon exporter and whether the human is a smoker. Radon, that comes from the materials in floors, ceiling, and walls can grant rise to increase the concentrations of indoor Radon. The size of Radon emission from different portions of the building relies on the concentration of Radium in the building material, also the materials humidity, permeability, and porosity, furthermore the thickness of the wall [3] 2

.Description of Study Area
Shaikh Omar region as shown in figure (1), is an old industrial area located on the side of Rusafa and specializes in the availability and repair of car equipment and is one of the most important industrial areas in Baghdad, including a number of factories, workshops that contain many types of metals, tools and equipment for work such as Computer Numerically Controlled (CNC) which is electro-mechanical device used to design several tools of metal.

Experimental
Two factories dating to 1930s were chosen to monitor in the industrial region (Shaikh Omar) which had many workers who where spending spend long periods in these places (7 Am to 3 Pm). It was, therefore, necessary to recognize the radiation levels and their health effects to ensure the safety of the worker. Twelve rooms were chosen randomly, which belong to different workshops that contained different types of metals and machines needed for their work. This study was done using, Solid-state nuclear detectors type CR-39 which distributed inside study positions in different numbers, and at a height of 150cm from the ground level. After an exposure time of 30 days, the parts of the detector was collected, and chemically etched by using NaOH at 60°C for 4.5 hours; the traces of alpha damage per unit area were counted using an optical microscope with a magnification of 400X. Figure (2) shows the calibration curve between the exposure of radon (Es) and the track density ( ) in unit tracks/mm 2 of the standard source ( 226 Ra) with an activity of 181692Bq. The concentration of Radon in the air (CRM) in the samples was calculated by the following relation [4].
= slope, that represents the calibration factor and it is obtained from the linear calibration curve in figure (2).
(ρ ) indicates to tracks density (in unit tracks/mm 2 ) from radon exposure inside the location which was calculated by dividing the average number of tracks per detector (10 readings were counted of each detector) by the area of the square (0.07mm 2 ). (t) Symbolizes the time of exposure (30 days). UNSCEAR2000 reports (United Nations Scientific Committee on the Effects of Atomic Radiation) consider that radon contributes 55% of the average annual dose per capita from natural sources. Continued exposure to radon at high concentrations can lead to lung cancer. is in allowable level at 150 Bq/m 3 in new buildings and 200 Bq/m 3 in old buildings [5]. After obtaining the radon concentrations, it can deduce the lung cancer with anther risk parameters as follow: 1. The Annual Effective Dose (AED) has been measured in a unit of (mSv/y) as follow:

Results and Discussion
The outcomes of radon concentration for twelve rooms in the two old factories which were calculated using equation (1)  117± 16.569Bg/m 3 . back to the 1930s and are poorly ventilated, that in these locations several types of chemicals materials Were used as well as different types of metals and equipment that were especial to these workshops. The average value of radon concentration was 244.19±61.52 Bg/m 3 which was within the universally allowed limit (200-300Bg/m 3 ) [10]. The health effects of this gas represented by annual effective dose (AED), lung cancer risk (LCR) per million people and exposure to radon progeny (EP) were listed in table(2). in this table, it can be seen that the values of AED were ranged from 3.110 mSv/y to 8.297 mSv/y, and with an average of 6.158 mSv/y which were within the universal limit (3-10 mSv/y) [10] . Also in table(2), and figure(4), the values of LCR were ranged from 55.993 to 149.346 per million people, and with an average of 110.855 per million people who were within the universal limit (170-230 per million people) [11].At last, in table(2), it can be noticed that the values of EP were ranged from (0.550 to 1.466 )WLM/Y, and with an average (1.088WLM/Y) which were lower than the accepted universal limits (1-2 WLM/Y) [7]. All result in this study more than another study in Baghdad governorate [12].

Conclusion
Outcomes showed that the average of radon concentration with its risk parameters inside these locations in spite of they were lower than the acceptable universal limits but some of these locations had a high value of radon concentrations that can pose a risk of lung cancer over time. also other sites had concentrations that could not be underestimated and should be continuously monitored to ensure safety of their workers. The results of radon health effects (AED, LCR and EP) were all within the acceptable limits given by ICRP, 2009. So, there was no cancer risk of radon in the two factories under study.