Sierra Club Analysis & Notes:

The below information was provided by the Sierra Club:

Results compared to RSL in soil

The results for two metals, Manganese and Thallium were above the EPA regional screening levels (RSL) for residential soil. Three results, Selenium, Cadmium and Cobalt, were above the Noncarcinogenic Screening Levels – Child criteria.  The following are brief descriptions of the hazards of each of these metals. Keep in mind that the described health impacts are based on chronic exposures that are above the listed screening levels and do not describe the effect of a single acute exposure.

• Manganese: Manganese in water poses minimal hazards, however, manganese is soil or dust does pose a significant hazard, especially through inhalation. Manganese toxicity can result in a permanent neurological disorder known as manganism with symptoms that include tremors, difficulty walking, and facial muscle spasms. These symptoms are often preceded by other lesser symptoms, including irritability, aggressiveness, and hallucinations. The average manganese soil concentrations in the United States is 40–900 mg/kg. Source: ATSDR – CDC. The maximum manganese level in this one soil sample was 293,000 mg/Kg. The screening level for a child that is listed is primarily based on ingestion of Manganese. The inhalation screening level for a child is 7,100 mg/Kg.

• Thallium: Thallium blood concentration levels are normal below 2 µg/L, and toxic at concentrations greater than 200 µg/L. DELAYED EFFECTS OF EXPOSURE: Long-term effects of thallium exposure can include difficulty walking, various involuntary movement disorders, and impairment of thought and mood. Source: NIOSH – CDC High concentration of thallium in shallow soil also poses a notable threat due to possible uptake by plant roots and storage in plant biomass. As a result, thallium may enter the food chain and accumulate in living organisms, causing severe disorders and ultimately becoming fatal. Source: National Library of Medicine. The screening level for a child that is listed is primarily based on ingestion of Thallium.

• Selenium: Selenium is a naturally occurring mineral required for good health. It is obtained from food, and the recommended dietary allowance is 55 μg/d for persons 14 years or older, with a tolerable upper intake limit of 400 μg/d. Selenium toxicity can occur with acute or chronic ingestion of excess selenium. Symptoms of selenium toxicity include nausea; vomiting; nail discoloration, brittleness, and loss; hair loss; fatigue; irritability; and foul breath odor (often described as “garlic breath”). Source: National Library of Medicine. The screening level for a child that is listed is primarily based on ingestion of Selenium.

• Cadmium: Cadmium (Cd) is a post-transition metal that has been found to exhibit biological toxicity that is “teratogenic, carcinogenic, and mutagenic.” It is easily absorbed by crops, causes harm to crop growth and development, affects crop quality and yield, and, as part of the food chain, leads to damage to the lungs, liver, kidneys, bones, and reproductive organs, causes toxic effects to the immune and cardiovascular systems, and is associated with various diseases. The Agency for Toxic Substances and Disease Registry (ATSDR), lists Cd as the sixth most toxic substance that endangers human health. Source: National Library of Medicine. The screening level for a child that is listed is primarily based on ingestion of Cadmium.

• Cobalt: Cobalt is a natural element found throughout the environment.  Acute (short-term) exposure to high levels of cobalt by inhalation in humans and animals results in respiratory effects, such as a significant decrease in ventilatory function, congestion, edema, and hemorrhage of the lung. Respiratory effects are also the major effects noted from chronic (long-term) exposure to cobalt by inhalation, with respiratory irritation, wheezing, asthma, pneumonia, and fibrosis noted.  Cardiac effects, congestion of the liver, kidneys, and conjunctiva, and immunological effects have also been noted in chronically-exposed humans.  Cobalt is an essential element in humans, as a constituent of vitamin B12.  Human studies are inconclusive regarding inhalation exposure to cobalt and cancer.  EPA has not classified cobalt for carcinogenicity. Source: US EPA. The screening level for a child that is listed is primarily based on ingestion of Cobalt.

• Potassium: Note that there is no EPA RSL or SL for Potassium but the maximum level in the soil sample was 71,600 mg/Kg (ppm). Potassium is a major plant nutrient. Healthy levels of potassium in soil range from 40 to 80 ppm. There are no severe health impacts related to ingestion or exposure to potassium. However, your total intake of potassium should not be greater than the recommended amounts, unless ordered by your doctor. In some cases, too much potassium may cause muscle weakness, confusion, irregular heartbeat, or difficult breathing. Source: Mayo Clinic

I don’t know what criteria that Brownfield, the City or EPA will use as comparison of the results. That is why I used listed Generic Regional Screening Levels. Besides comparing each result to some criteria, Cumulative Impacts are something that needs to be considered by the responsible parties. Many of the symptoms of over-exposure to these metals are common and result in similar endpoints and so, in a cumulative or additive manner, can be more harmful in combination.