📄 earth_science

Measuring radon gas concentration in fertilizers and pesticides using anuclear track detector CR ₋ 39

This study utilized CR-39 nuclear track detectors to measure radon concentrations in 29 fertilizer and pesticide samples, finding that while levels varied significantly, all results remained well below international safety limits, indicating no significant radiological risk under normal usage conditions.

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

Published 2026-07-03

📖 4 min read☕ Coffee break read

CC BY 4.0

Original authors: Adnan A. Mohammed, 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 you have a garden, and you want to make sure the soil is healthy. You buy bags of fertilizer and bottles of pesticide to help your plants grow. But have you ever wondered if those bags and bottles might be hiding a tiny, invisible guest?

This research paper is like a "health check" for 29 different bags of fertilizer and bottles of pesticide. The scientists wanted to see if these common gardening supplies were releasing Radon gas.

What is Radon?

Think of Radon as a ghostly, invisible gas that comes from the natural decay of rocks and soil (specifically from uranium and radium). It's like a radioactive "fume" that can drift into the air. While it's natural, breathing in too much of it over a long time can be bad for your lungs, much like smoking is bad for your health.

The Detective Tool: The CR-39 Detector

To catch this invisible gas, the researchers used a special tool called a CR-39 detector.

The Analogy: Imagine a piece of plastic that acts like a "flypaper" for invisible bullets. When Radon gas decays, it shoots out tiny, high-speed particles called alpha particles. These particles are too small to see with the naked eye, but when they hit the CR-39 plastic, they leave tiny scratches or "tracks," just like a bullet leaving a mark on a target.
The Process: The scientists put small amounts of fertilizer and pesticide (about the weight of a small apple slice) into sealed plastic cups. They stuck a piece of this special plastic inside the cup and left it alone for 90 days (about three months). This gave the gas plenty of time to escape the sample and hit the plastic.

The Investigation Results

After three months, they took the plastic out, washed it with a special chemical solution (like developing a photo), and looked at it under a powerful microscope to count the "bullet holes" (tracks).

Here is what they found:

1. The Fertilizer Check (17 samples)

The Range: The amount of Radon varied wildly, like a rollercoaster.
- The "quietest" sample was a Saudi product called Lipro, which had almost no Radon (4.12 units).
- The "loudest" sample was a Jordanian product called Smart Fert, which had the most Radon (108.63 units).
The Average: On average, the fertilizers had a Radon level of about 30.46 units.

2. The Pesticide Check (13 samples)

The Range: These also varied.
- The lowest was an Indian product called Venus (9.27 units).
- The highest was a Chinese product called Efecekt (82.24 units).
The Average: The pesticides averaged about 27.28 units.

The Verdict: Are They Safe?

The scientists compared their findings to the "speed limits" set by global safety organizations (like the WHO and ICRP).

The Speed Limit: The safe limit for Radon in the air is generally considered to be between 100 and 300 units.
The Result: Even the "loudest" samples (the ones with the most Radon) were still well below this safety speed limit.
- The highest fertilizer reading (108.63) was just barely over the lowest safety threshold but still far below the danger zone.
- Most samples were significantly lower than the limit.

They also measured the "Potential Alpha Energy Concentration" (PAEC), which is like measuring the total punch of all the radioactive particles combined.

The highest "punch" they found was 23.48 units (in the Jordanian fertilizer).
The global safety limit for this "punch" is 53.33 units.
Conclusion: Even the strongest samples were only about half as strong as the danger zone.

The Bottom Line

The paper concludes that while these fertilizers and pesticides do contain some natural radioactive material (because they are made from rocks and soil), the amount of Radon gas they release is low enough to be considered safe for normal use.

Think of it like this: If the safety limit is a "Do Not Enter" sign on a bridge, these samples are standing comfortably on the sidewalk, far away from the edge. The scientists say that under normal conditions, using these products does not pose a significant radiation risk to farmers or the environment. However, they suggest we should keep an eye on things to make sure they stay that way.

Technical Summary: Measuring Radon Gas Concentration in Fertilizers and Pesticides Using a CR-39 Nuclear Track Detector

Problem Statement
The study addresses the potential radiological hazards associated with the use of chemical fertilizers and pesticides in agriculture. While radon-222 ( $^{222}\text{Rn}$ ) is a naturally occurring noble gas derived from the decay of radium-226 in the Earth's crust, its concentration can be elevated in agrochemical products due to the raw materials used (particularly phosphate rocks containing uranium-238 series nuclides). The accumulation of radon and its decay products in the environment poses a health risk, specifically increasing the probability of lung cancer upon inhalation. The research aims to quantify radon activity concentrations and evaluate associated radiological hazards in 29 commercial samples of fertilizers and pesticides to determine if they exceed internationally accepted safety limits.

Methodology
The researchers employed a solid-state nuclear track detector (SSNTD) technique using CR-39 plastic detectors.

Sample Collection: A total of 30 samples were collected from agricultural distribution centers in the Salah al-Din governorate, Iraq. This included 17 fertilizer samples and 13 pesticide samples sourced from various international origins (e.g., Jordan, Saudi Arabia, China, India, Italy, and the UAE).
Experimental Setup: Each sample (12.5 g) was placed in a hermetically sealed, non-permeable cylindrical chamber made of polypropylene to prevent radon leakage. The chambers featured a specific geometry (6 cm top diameter, 4 cm bottom diameter, 7 cm height above the cover, and 1 cm sample thickness).
Detection: CR-39 detectors (approx. 1 cm²) were affixed inside the chambers to record alpha particles emitted during radon decay.
Exposure and Etching: The detectors were exposed for 90 days. Following exposure, they were chemically etched in a 6.25 N sodium hydroxide solution at 60°C for 5 hours to reveal alpha particle tracks.
Analysis: Tracks were counted under a microscope at 400x magnification. Radon concentration ( $C_{Rn}$ ) was calculated using track density ( $\rho_{Rn}$ ), exposure time ( $t$ ), and a calibration factor ( $K$ ) derived from the chamber geometry and detector sensitivity. The potential alpha energy concentration (PAEC) was also calculated to assess radiological hazard indices.

Key Results
The study revealed significant variability in radon concentrations across the different samples, attributed to the specific raw materials and manufacturing processes of each product.

Fertilizers:
- Range: Radon concentrations varied from a low of 4.12 Bq·m⁻³ (Saudi product "Lipro") to a high of 108.63 Bq·m⁻³ (Jordanian product "Smart Fert").
- Mean: The average radon concentration for fertilizers was 30.46 Bq·m⁻³.
- PAEC: The potential alpha energy concentration ranged from 0.89 mWL to 23.48 mWL, with a mean of 8.05 mWL.
Pesticides:
- Range: Concentrations ranged from 9.27 Bq·m⁻³ (Indian product "Venus") to 82.24 Bq·m⁻³ (Chinese product "Efecekt").
- Mean: The average radon concentration for pesticides was 27.28 Bq·m⁻³.
- PAEC: The PAEC ranged from 2.05 mWL to 17.78 mWL, with a mean of 5.89 mWL.

Significance and Claims
The paper asserts that all measured radon concentrations and PAEC values fall well within globally accepted safety limits.

Comparison to Standards: The results are significantly below the reference range of 100–300 Bq·m⁻³ recommended by the International Commission on Radiological Protection (ICRP Publication 126, 2014) and the more conservative 100 Bq·m⁻³ level suggested by the World Health Organization (WHO, 2009).
Hazard Assessment: The study concludes that the investigated fertilizers and pesticides do not pose significant radiological risks under normal conditions of use, as no sample exceeded the internationally accepted action levels.
Contextual Findings: The authors note that the presence of radiological effects in phosphate fertilizers is linked to the concentration of uranium-238 and radium-226 during the production process, while pesticide radioactivity is related to their chemical structure and environmental conditions.

Conclusion
The study confirms that while radon exhalation varies among different agrochemical products based on their origin and composition, the current levels in the tested samples are safe. The authors emphasize that while the materials are within safety limits, ongoing monitoring is essential to ensure these levels remain acceptable, and further research could explore the specific sources of variation to better understand environmental health implications.