Old Railway Sleepers: A Hidden Danger for Your Garden and Home

At first glance, they seem like the perfect material for any DIY enthusiast—old railway sleepers are an appealing choice for gardeners and handymen. Their robust appearance, relative availability, and apparent durability make them attractive for landscaping projects such as raised garden beds, pathway borders, or even components of terraces or outdoor furniture. However, few realize that these seemingly harmless pieces of wood conceal serious health and environmental risks. 

In this article, prepared for Watrex Praha by RNDr. Roman Kysilka, CSc., we’ll explore not only why using old sleepers outside the railway network is problematic but also how harmful substances in these materials can be identified using modern analytical methods. We’ll introduce the SCS 205 Sample Clean-up System, a device that plays a key role in the analysis. 

Take a closer look with us—both literally and analytically—at what lies inside this seemingly innocent wood.

Watrex: Introductory illustrative photograph

Why Are Old Sleepers So Risky? The Key Issue Is Creosote Treatment 

The main reason to avoid using old railway sleepers is the way they were preserved. For decades, sleepers were treated with creosote—a dark, oily substance derived from tar. 

Creosote is extremely effective at protecting wood from rot, mold, and pests, which extends the lifespan of sleepers in harsh outdoor environments. However, this same effectiveness is also linked to its high toxicity. Creosote is classified as a carcinogen. It contains hundreds of chemical compounds, the most concerning of which are polycyclic aromatic hydrocarbons (PAHs). Long-term contact with creosote components—through inhalation or ingestion (for example, via contaminated produce)— can lead to a range of health problems, including: 

• Cancer: Creosote is considered a probable human carcinogen. Skin contact can cause skin cancer, and the risk increases with inhalation of fumes. 
• Skin and Eye Irritation: Direct contact with creosote-treated sleepers can lead to severe irritation, rashes, blisters, and itching. 
• Respiratory Issues: Inhaling creosote vapors can irritate the respiratory tract, causing coughing and breathing difficulties, especially for individuals with asthma or other respiratory conditions. 
• Liver and Kidney Damage: Long-term exposure may impact liver and kidney function. 
• Photosensitivity (Phototoxicity): Creosote can increase skin sensitivity to sunlight, leading to more severe sunburns.

Environmental Burden: Toxic Substances in Soil and Water 

Beyond direct health risks, old sleepers pose a serious environmental threat. Toxic substances are gradually released from the sleepers into their surroundings through rain, sunlight, and soil microbes. These toxins accumulate in the soil, where they can be absorbed by plants. Fruits and vegetables grown in contaminated soil may contain harmful substances that ultimately end up on your plate. 

Additionally, if sleepers are placed near water sources, the toxic compounds may leach into groundwater and contaminate wells or surface water bodies. This not only endangers human health but also threatens wildlife and aquatic ecosystems. Burning sleepers is absolutely unacceptable, as it releases highly toxic pollutants into the air.

Watrex Image 2: Illustrative photo of a bench made from railway sleepers.

Legislative Restrictions and Recommendations 

In many countries, including the Czech Republic and the European Union, the use of creosote and the handling of creosote-treated sleepers are regulated. New sleepers are no longer treated with creosote. The sale of old sleepers for domestic use is banned within the EU, with exceptions made only for specific industrial applications where exposure risk is minimal. These regulations aim to protect public health and the environment. Nevertheless, such sleepers can still occasionally be found in online listings. 

Railway Sleepers from the Perspective of Analytical Chemistry

Determining the content of polycyclic aromatic hydrocarbons (PAHs) in railway sleepers is essential for assessing environmental risks and ensuring proper disposal or recycling. Since PAHs are a complex mixture and their concentrations in sleepers can vary, it is crucial to follow a standardized and robust analytical procedure. The following outlines a typical workflow: 

1. Sampling 

Representative sampling is essential for obtaining reliable results. Due to the variability in sleepers (different impregnation levels, ages, environmental exposure), samples must be collected from various locations and depths within the sleeper. 

2. PAH Extraction 

PAHs are tightly bound within the wood matrix, so they must be extracted using a suitable solvent. The process involves drying and milling—the wood samples are first dried (preferably at a low temperature to prevent loss of volatile PAHs) and then ground into a fine powder to increase surface area and extraction efficiency. Various extraction techniques are used, typically involving organic solvents (such as hexane, dichloromethane, toluene, or mixtures thereof), which are effective for PAHs. Extraction is usually done via traditional Soxhlet extraction (a time-intensive method), ultrasonic extraction, pressurized liquid extraction, or microwave-assisted extraction. 

3. Extract Cleanup 

Extracts contain not only PAHs but also other interfering compounds (e.g., lignins, cellulose, resins) that can disrupt subsequent instrumental analysis. Therefore, the extract must be purified. Common methods include solid-phase extraction (SPE) using silica gel, Florisil, or C18 phases, or easily automated liquid chromatography

The Watrex SCS 205 Sample Clean-up System utilizes gel permeation chromatography with a preparative column filled with pressure-resistant sorbent. This significantly shortens sample preparation time compared to traditional soft-gel column chromatography. The system includes a pump, injection valve, fraction collector, and control unit.

Watrex Image 3: Watrex SCS 205 GPS Sample Cleanup System

4. Instrumental Analysis (PAH Quantification) 

To determine and quantify PAHs, highly sensitive and selective chromatographic methods are most commonly used: 

• Gas Chromatography with Mass Spectrometry (GC-MS) 
• High-Performance Liquid Chromatography (HPLC) with Fluorescence or UV Detection 

Given the typically high concentrations of PAHs (ranging from hundreds to thousands of mg/kg), a cost-effective method such as HPLC with UV detection is often suitable for this type of analysis. 

Health and Safety First 

The aesthetics and practicality of railway sleepers may be tempting, but they come with a toxic price—paid with the health and safety of your surroundings. Instead of using contaminated materials, choose eco-friendly and non-toxic alternatives. Your garden and home should be places of relaxation and safety, not sources of hazardous substances.

If you have an old piece of wood in your garden and are unsure of its origin or safety, don’t hesitate to contact us. At Watrex Praha, we’ll be happy to help—simply send us a sample, and we’ll perform a professional PAH analysis to determine whether the material contains harmful substances. 

Your health and safety are definitely worth it.