Evaluation of Health Risks from Consuming Vegetation Foraged
in Kelly Brook Wetlands in the Vicinity of the Beede Waste Oil NPL Site
BEEDE WASTE OIL SITE
PLAISTOW, ROCKINGHAM COUNTY, NEW HAMPSHIRE
The New Hampshire Office of Health Management (OHM), Bureau of Health Risk Assessmentreceived an inquiry from a resident who lives near the Beede Waste Oil NPL site who wasconcerned about health risks from consuming vegetation foraged in the wetlands along Kelley Brooknear the Beede site. The resident collects a plant called a Marsh Marigold (Caltha Palustris) thatgrows in the sediments near Kelley Brook. This plant is harvested for consumption in late Marchthrough April before it blooms. The harvest period is approximately six weeks. After that time theplant tissue becomes bitter and inedible. The leaves are collected,cooked, and eaten similar tospinach. The leaves are not eaten raw because the plant produces a natural toxin called helleborinwhich is removed by boiling. The total amount harvested is estimated to be enough for about sixmeals1, with each meal estimated on the average to be 86 grams, similar to the average quantity ofspinach consumed per meal2. According to this resident, no other wild plants are harvested fromKelley Brook wetlands.
Sediment samples were taken from Kelley Brook in October 1997 by The New HampshireDepartment of Environmental Services and Sanborn, Head and Associates as part of the remedialinvestigation process at the Beede Waste Oil Site. Sampling showed elevated concentrations ofmetals and organic compounds. Plants can accumulate metals from soil and sediment, and wheneaten can result in a completed human exposure pathway to these contaminants. Analytical resultsfor sediment metal contaminant levels are presented in Table 1.
|Metal||Range of concentration (mg/kg)||Mean concentration (mg/kg)|
|Arsenic||4.80 - 35.30||11.29|
|Cadmium||0.96 - 2.10||1.48|
|Mercury||0.06 - 0.17||0.11|
|Nickel||13.20 - 42.3||21.88|
|Selenium||0.81 - 3.10||1.55|
|Zinc||28.70 - 159||93.10|
The metals concentrations in sediments were compared to soil screening levels (SSL) specificallydeveloped for the soil-plant-human pathway by EPA3. These screening levels define theconcentration of metals in soils that are below levels of concern for cancer and non-cancer humanhealth effects from ingesting plants grown in metal contaminated soils. Arsenic was the only metalthat was above its soil screening level (see Table 2) at both mean and maximum concentrations.
No screening levels are currently available for plant uptake of organic contaminants fromcontaminated sediments and soils. It is assumed that uptake of organic contaminants in soil into theleaf tissues is negligible4. It is further assumed that exposure to organic contaminants deposited onthe leaf surface is minimal because the contaminant is removed during washing and cooking.
No ATSDR comparison values are available for the soil-plant-human exposure pathway, though thesediment arsenic concentrations exceeded the cancer risk evaluation guideline (CREG) and childenvironmental media evaluation guideline (EMEG) for direct soil ingestion. CREG and EMEGs aremedia specific concentrations of chemicals that do not pose a risk for adverse human health effects,and are similar to SSLs. The screening levels and comparison values for arsenic are presented in Table 2.
|SSL||Child EMEG||Adult EMEG||CREG|