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Measurement of Radon Gas Concentration in Fertilizers and Pesticides Using the CR-39 Nuclear Trak Detector

This study utilized CR-39 nuclear track detectors to measure radon gas concentrations and potential alpha energy in 29 fertilizer and pesticide samples from Tikrit, Iraq, finding that all values remained well below international safety limits and confirming the radiological safety of these agricultural products under normal use.

Original authors: Adnan A. Muhammed, Asmaa A. Aziz

Published 2026-07-01

📖 4 min read☕ Coffee break read

CC BY 4.0

Original authors: Adnan A. Muhammed, Asmaa A. Aziz

Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

Imagine your garden is a bustling city. In this city, there are invisible "ghosts" called Radon gas (specifically 222Rn). These ghosts are naturally born from rocks and soil, but they can also hitch a ride on things we use to grow our food, like fertilizers and pesticides. If too many of these ghosts gather in one place, they can be harmful to our health, much like too much smoke in a room.

This study is like a detective investigation into the "ghost population" inside bags of fertilizer and bottles of pesticide sold in Tikrit, Iraq. The researchers wanted to know: Are these gardening supplies hiding a dangerous amount of invisible radioactive gas?

The Detective's Tool: The CR-39 "Flypaper"

To catch these invisible ghosts, the scientists didn't use a vacuum or a camera. Instead, they used a special piece of plastic called a CR-39 detector.

Think of this detector as super-sensitive flypaper.

The Setup: The researchers took small amounts of fertilizer and pesticide (about the size of a sugar cube) and put them in sealed plastic jars.
The Trap: They stuck a piece of this "flypaper" to the inside of the jar lid, about 7 centimeters away from the sample.
The Wait: They sealed the jars and left them alone for 90 days. During this time, if any Radon gas escaped from the sample, it would float up and hit the flypaper.
The Reveal: When the gas hit the plastic, it left tiny, invisible scratches (tracks). The scientists then soaked the plastic in a chemical bath (like a developer for old photos) to make these scratches visible. Finally, they looked at them under a microscope to count how many "ghosts" had landed.

The Findings: A Tale of Two Gardens

The team tested 29 different products: 16 types of fertilizer and 13 types of pesticides. These came from all over the world, including Jordan, Saudi Arabia, China, India, and Europe.

1. The Fertilizer Results (The "Soil Food")

The Range: The amount of Radon gas varied wildly. Some fertilizers had almost no ghosts (4.12 units), while others had a lot (108.63 units).
The Champions: The fertilizer with the most "ghosts" was a Jordanian brand called Smart Fert. The one with the least was a Saudi brand called Libro.
The Cause: The study suggests that fertilizers made from phosphate rocks (which naturally contain radioactive elements) tend to have more Radon, just like a house built on a rocky foundation might have more drafts.

2. The Pesticide Results (The "Bug Spray")

The Range: The pesticides also showed a wide variety. The highest was a Chinese brand called Efecekt, and the lowest was an Indian brand called Venus.
The Cause: Just like fertilizers, the "ghost count" depended on what the pesticide was made of and where its ingredients came from.

The Big Question: Is it Safe?

The researchers compared their findings to the International Safety Limits. Imagine a speed limit sign on a highway:

The Limit: The safe speed limit for Radon gas is 200 units.
The Reality: The fastest fertilizer was going 108 units, and the fastest pesticide was going 82 units.

The Verdict:
Even though some products were "speeding" compared to others, none of them broke the speed limit.

The average fertilizer was driving at about 30 units.
The average pesticide was driving at about 27 units.

The study also looked at "Potential Alpha Energy" (PAEC), which is like measuring the total "punch" of all the ghosts combined. Again, the highest punch was far below the safety barrier.

The Conclusion

The researchers concluded that, based on this investigation, all the fertilizers and pesticides tested are radiologically safe for normal use. They are not dangerous to human health or the environment under regular conditions.

However, just like a city needs traffic police to keep drivers safe, the researchers recommend periodic checks. Since the "ghost levels" depend on where the raw materials come from and how they are made, it's important to keep monitoring these products to ensure they stay within the safe zone.

In short: The invisible ghosts in these garden supplies are present, but they are currently too few to cause any harm. The tools used to catch them worked perfectly, and the results are good news for gardeners.

Technical Summary: Measurement of Radon Gas Concentration in Fertilizers and Pesticides Using the CR-39 Nuclear Trak Detector

Problem Statement
Naturally Occurring Radioactive Materials (NORMs), specifically $^{238}\text{U}$ and $^{226}\text{Ra}$ , are often present in agricultural products due to the geological composition of raw materials and manufacturing processes. Fertilizers, particularly those derived from phosphate rocks, and pesticides can act as sources of $^{222}\text{Rn}$ (Radon) gas release. Given that $^{222}\text{Rn}$ and its short-lived decay products contribute significantly to the annual effective dose of natural radiation and are linked to lung cancer, assessing their concentration in agricultural inputs is critical for radiological safety. While previous studies have examined fertilizers, there is a scarcity of data regarding $^{222}\text{Rn}$ concentrations and Potential Alpha Energy Concentration (PAEC) in commercial fertilizers and pesticides specifically within Iraq.

Methodology
The study employed a passive monitoring technique using CR-39 nuclear track detectors to measure $^{222}\text{Rn}$ concentrations and PAEC.

Sample Collection: A total of 29 samples were collected from agricultural markets and farming offices in Tikrit, Salah Al-Din Governorate, Iraq. This included 16 fertilizer samples and 13 pesticide samples from various countries of origin (e.g., Jordan, Saudi Arabia, China, India, UAE, Turkey).
Experimental Setup: Samples (12.5 g each) were placed in sealed cylindrical polypropylene containers. CR-39 detectors (approx. 1 cm²) were fixed to the inner lid surface, positioned 7 cm above the sample surface.
Exposure and Processing: The sealed containers were stored for an exposure period of 90 days to allow for the accumulation of alpha-particle tracks. Post-exposure, detectors were chemically etched in 6.25 N NaOH at 60°C for 5 hours.
Analysis: Alpha-particle tracks were counted using an optical microscope at 400× magnification. Track densities were converted to $^{222}\text{Rn}$ concentrations (Bq/m³) and PAEC (mWL) using specific calibration factors and formulas accounting for the chamber geometry, detector critical angle, and decay constants.
Statistical Analysis: Descriptive statistics were calculated, and the Mann-Whitney U test was applied to compare the radiological parameters between fertilizer and pesticide groups, as the data did not follow a normal distribution (Shapiro-Wilk test, p < 0.05).

Key Results

Radon Concentrations:
- Fertilizers: $^{222}\text{Rn}$ concentrations ranged from 4.12 to 108.63 Bq/m³, with a mean of 30.46 Bq/m³ (median 34.62 Bq/m³). The highest value was recorded in the Jordanian fertilizer "Smart Fert" (F16), and the lowest in the Saudi fertilizer "Libro" (F9).
- Pesticides: Concentrations ranged from 9.27 to 82.24 Bq/m³, with a mean of 27.28 Bq/m³ (median 16.69 Bq/m³). The highest value was found in the Chinese pesticide "Efecekt" (P7), and the lowest in the Indian pesticide "Venus" (P11).
Potential Alpha Energy Concentration (PAEC):
- Fertilizers: PAEC values ranged from 0.89 to 23.48 mWL, with an average of 8.05 mWL.
- Pesticides: PAEC values ranged from 2.05 to 17.78 mWL, with an average of 5.89 mWL.
Statistical Comparison: While fertilizer samples showed slightly higher mean values for both $^{222}\text{Rn}$ concentration and PAEC compared to pesticides, the Mann-Whitney U test indicated no statistically significant difference between the two groups (p = 0.2113 for both variables).
Variability: High coefficients of variation were observed for both groups (64.91% for fertilizers and 78.41% for pesticides regarding $^{222}\text{Rn}$ ), attributed to differences in raw material composition, phosphate content, and manufacturing processes.

Significance and Claims
The primary significance of this work lies in providing the first localized radiological assessment of commercial fertilizers and pesticides in the Tikrit region of Iraq. The study claims that despite the observed variations in radioactivity levels among different brands and origins, all measured values are well below the internationally recommended safety limits established by the ICRP (200 Bq/m³ for $^{222}\text{Rn}$ ) and UNSCEAR (53.33 mWL for PAEC).

Consequently, the authors conclude that the investigated fertilizers and pesticides are radiologically safe for use under normal agricultural conditions and do not pose an immediate threat to human health or the environment. However, the paper emphasizes the necessity of periodic monitoring to ensure continued compliance with safety standards, noting that radiological properties are heavily dependent on the specific raw materials and production methods used by different manufacturers.

The Detective's Tool: The CR-39 "Flypaper"

The Findings: A Tale of Two Gardens

The Big Question: Is it Safe?

The Conclusion

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