Comparing 6 Common Salt Types & Differences in Toxic Content

Salt is a staple in kitchens worldwide, vital for its ability to transform dishes, and, when using high quality types, even our health. See, salt is a source of electrolytes that the body needs to function properly especially now in our chronically dehydrated world.

From the refined grains of table salt to the coarse crystals of kosher salt, the mineral-rich flakes of sea salt, and the lovely pink granules of Himalayan salt, to the pristine and mineral dense Icelandic Flake Sea Salt -  each type of salt comes with its own story, processing technique, and set of culinary applications.

Icelandic Flake Salt is the most electrolyte rich, tested to have an industry low in heavy metals and zero microplastics.

However, as our understanding of environmental and health issues deepens, so does our concern for what these might mean for our most basic of seasonings.

Recent studies shed light on the presence of microplastics and heavy metals in various salts, raising questions about the purity of these essential kitchen staples. Psst - stay tuned and keep reading this blog for a chart that compares minerals content, microplastic content and heavy metals content of several salt brands.

This in depth blog will guide you through the intricacies of how different salts are processed and what you, as a consumer, should know about the salt on your table.

Whether it’s the concern for microplastics in our seas finding their way into sea salt or the heavy metals unearthed by mining activities contaminating Himalayan and table salts, understanding these issues is crucial for making informed choices about the salt we consume... especially now when heavy metal and microplastic exposure is everywhere.

Ready? Let's go. 

Table Salt: The Kitchen Staple

Table salt is the most ubiquitous type of salt found in households. It's highly refined and finely ground, with anti-caking agents like calcium silicate added to prevent clumping, and often iodized to support thyroid health.

The production of table salt involves drilling into underground salt deposits to create a brine, which is then evaporated using artificial heat. This process removes impurities and minerals, resulting in pure, white salt that's consistent in flavor and appearance.

How Table Salt is Processed:

1. Extraction: The production begins with the extraction of salt from underground deposits, often through drilling. Water is injected into the salt beds to dissolve the salt, creating a brine.
2. Evaporation: The brine is then pumped out and transported to a processing facility, where it is heated to evaporate the water, leaving behind salt.
3. Refining: The raw salt undergoes a refining process where impurities are removed. This stage might involve washing the salt with water and then re-evaporating it.
4. Addition of Additives: Post-refinement, additives such as anti-caking agents (e.g., calcium silicate) are mixed in to prevent clumping. Iodine may also be added at this stage to produce iodized salt, which helps prevent iodine deficiency disorders.
5. Milling: Finally, the salt is milled to a fine consistency. The milling process allows the salt to achieve its uniform, fine texture, making it ideal for a wide range of culinary applications.

Microplastics and Heavy Metals in Table Salt

• Microplastics: Since table salt is typically mined from underground deposits, microplastic contamination is likely to happen during the  extraction of seawater and manufacturing processes. 
  
  In fact, a 2024 study published in the Global Journal of Environmental Science and Management found table salt contains a shocking number of microplastics - detecting up to 33 microplastics per kg of table salt.
  
  There were 4 types of polymers present: polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and polyester. PE is commonly used in synthetic resins, PP in robust, heat-resistant plastics, PET in clothing fibers and containers for liquids and foods, and polyester in man-made fiber materials. 
  
  During the processing and refining of salt, microplastics contamination can occur from equipment or during the addition of anti-caking agents, which may contain impurities.
  
  The problem is so pervasive, that studies show 90% of table salt contains microplastics.
  
  
  
• Heavy Metals: The use of heavy machinery and explosives in mining introduces heavy metal contamination in table salt.

Kosher Salt: The Chef's Choice

Kosher salt, with its coarser, flakier texture, is a favorite among chefs for seasoning by hand. It lacks the anti-caking agents and iodine found in table salt, which allows it to dissolve nicely in cooking while providing a clean, straightforward saltiness. The larger grains offer more control over the seasoning process, making it an indispensable tool in the culinary world.

How Kosher Salt is Processed:

1. Extraction: Similar to table salt, kosher salt can be harvested from salt mines or by evaporating seawater. 
2. Evaporation/Processing: For mined kosher salt, the process involves extracting the salt, dissolving it into a brine, and then evaporating the water. For sea salt-based kosher salt, natural evaporation methods are typically used.
3. Screening and Grading: After evaporation, the salt crystals are screened and graded based on size. Kosher salt is known for its larger, coarser grains, which are less processed than those of table salt.
4. Minimal Refining: Unlike table salt, kosher salt undergoes minimal processing, which means it retains more natural trace minerals and does not include additives like anti-caking agents or iodine. This results in its characteristic flaky, coarse texture that chefs prefer for seasoning.

Microplastics and Heavy Metals in Kosher Salt

• Microplastics: Like table salt, kosher salt can be sourced from both seawater and underground deposits. Its risk of microplastic contamination would similarly depend on the source, with sea salt-based kosher salt having a potentially higher risk.
  
  Industrial waste and agricultural runoff can contaminate seawater or underground brine with heavy metals like mercury, lead, arsenic, and cadmium. These pollutants can enter the salt during the evaporation process.
  
  
• Heavy Metals: Due to its larger crystal size and less intensive refining process compared to table salt, yet heavy metals is still a risk.
  
  Due to lack of transparency in major salt producers, we don't know exactly how bad the toxic content is.

Sea Salt: The Flavor Enhancer

Sea salt is derived from the evaporation of seawater, available in both fine and coarse crystals. It retains trace minerals absent in table salt, contributing to a more complex flavor profile. There are various methods of harvesting sea salt, each lending unique characteristics to the final product:

Pan Harvested Sea Salt:

Utilizes natural evaporation in shallow pools, maintaining the seawater's trace minerals.

How Pan Harvested Sea Salt is processed:

1. Collection of Seawater: Seawater is collected into shallow pans or evaporation ponds.
2. Natural Evaporation: The water is left to evaporate under the sun and wind, a process that can take several months.
3. Harvesting: Once the water has evaporated, the salt is harvested manually, keeping the natural trace minerals intact.
4. Drying: The harvested salt is further dried, sometimes in the sun, to achieve the desired moisture content.

Mined Sea Salt:

Involves extracting salt from ancient underground seawater deposits using heavy machinery. Though it may undergo processing to achieve purity, it still retains a more nuanced flavor than table salt.

How Mined Sea Salt is processed:

1. Extraction: Salt is extracted from ancient seabed deposits using heavy machinery.
2. Crushing and Screening: The extracted salt blocks are crushed and screened to remove debris and to grade the salt by size.
3. Washing and Drying: The salt may be washed to remove impurities and then dried.
4. Refining: Depending on the desired purity and use, the salt may undergo additional refining, though generally less than table salt.

Microplastics and Heavy Metals in Sea Salt

• Microplastics: Sea salts derived directly from evaporating seawater have raised concerns over microplastic contamination.
  
  Recent studies have found microplastics in sea salts around the world, reflecting broader oceanic pollution issues.
  
  To avoid microplastic contamination, look for sea salts sourced from pristine, pollution free areas.
  
  
• Heavy Metals:
  
  
  • Pan Harvested Sea Salt: Utilizes natural evaporation, limiting direct contact with machinery that could introduce heavy metals. However, the water source itself may contain heavy metals due to environmental pollution.
    
    
  • Mined Sea Salt: The use of heavy machinery and possibly explosives in extracting salt from ancient seabeds could lead to heavy metal contamination.
    
    The initial extraction of salt involves disturbing the soil and rock layers. Heavy machinery and explosives can unearth and distribute heavy metals that are naturally present in these geological layers. When these metals are brought to the surface, they can mix with the salt being extracted.
    
    Heavy machinery used in mining operations, including excavators, drills, and transport vehicles, can also be a source of contamination. Metals from the machinery itself, such as chromium, lead, and nickel, can leach into the salt during extraction and transportation processes.
    
    The use of explosives in mining can introduce chemical residues into the environment. Some components of explosives or their byproducts might contain heavy metals, which could contaminate the salt as it is being mined.
    
    Soil and Rock Disturbance: The initial extraction of salt involves disturbing the soil and rock layers. Heavy machinery and explosives can unearth and distribute heavy metals that are naturally present in these geological layers. When these metals are brought to the surface, they can mix with the salt being extracted.
    
    Metal Leaching from Equipment: Heavy machinery used in mining operations, including excavators, drills, and transport vehicles, can also be a source of contamination. Metals from the machinery itself, such as chromium, lead, and nickel, can leach into the salt during extraction and transportation processes.
    
    Explosive Residues: The use of explosives in mining can introduce chemical residues into the environment. Some components of explosives or their byproducts might contain heavy metals, which could contaminate the salt as it is being mined. 

Himalayan Pink Salt

Himalayan pink salt, recognized for its striking pink hue, is mined from ancient salt deposits in Pakistan. The harvesting process is meticulous, involving hand-extraction, sorting, crushing, and grinding to maintain its natural structure and mineral content. This minimal processing ensures that Himalayan pink salt retains its rich mineral profile, offering a healthier alternative to refined table salt.

How Himalayan Pink Salt is processed:

1. Mining: Authentic Himalayan Pink salt is mined in the Khewra Salt Mine in Pakistan.
2. Hand-Extraction and Sorting: Large blocks of salt are extracted and then broken down into smaller pieces by hand. This allows for the selection of salt with the best quality and color.
3. Crushing and Grinding: The selected salt pieces are then crushed and ground to the desired size. This process is often done mechanically, though it aims to preserve the salt's natural mineral content.

Microplastics and Heavy Metals in Himalayan Pink Salt:

• Microplastics: A 2023 study testing table salt, black salt, sea salt, iodized salt, rock salt, fine Himalayan Pink Salt and coarse Himalayan Pink Salt found that Coarse Himalayan Pink Salt was found to have the highest microplastics load.
  
  
• Heavy Metals: Concerns are newly coming to light about the heavy metal toxicity of what was once known as the healthier salt. According to a 2020 study, one pink salt sample contained a level of lead (>2 mg/kg) that exceeded the national maximum contaminant level set by Food Standards Australia New Zealand.