NEW HANOVER COUNTY — An estimated 125,211 people living in New Hanover County may be already exposed to methyl bromide at levels in excess of federally-recommended chronic exposure measurements.
Chronic exposure in humans is defined by the Environmental Protection Agency (EPA) as repeated oral, dermal, or respiratory exposure for more than 10 percent of a lifespan.
Two log fumigation sites in New Hanover County — both owned by Royal Pest Solutions — operate using state-issued Synthetic Minor permits. With one fumigation operation on River Road and one at the Port of Wilmington, overlapping portions of the population may be exposed to methyl bromide emissions.
The North Carolina Division of Air Quality (DAQ) is proposing a rule change for the toxicant believed to cause both acute and chronic neurological and respiratory system damage to humans. Under the change, methyl bromide would be added to the state’s list of Toxic Air Pollutants (TAP) which would allow regulators the ability to establish an Acceptable Ambient Level (AAL) of the compound beyond the fenceline of a facility. Establishing an AAL and requiring control measures could reduce total emissions from North Carolina’s five existing and future yellow pine log fumigation operations.
The DAQ is accepting public comment on the rule change until Friday.
Methyl Bromide
Methyl bromide is a compound used to rid pests and wood-boring insects from logs. In North Carolina, logging companies export their product to Asian markets which often require either the application of methyl bromide or debarking measures to prevent the spread of non-indigenous species.
Typically applied within storage containers, logs are fumigated for a period of 14-to-72 hours. When complete, storage container doors or tarps are uncovered and the toxic gas is released into the atmosphere. In North Carolina, no control mechanisms limiting or capturing methyl bromide emissions are required or in place at existing fumigation operations, according to a DAQ report approved in May.
The only existing public protection to these operations is a state requirement that fumigators limit methyl bromide emissions to 10 tons a year. No additional federal or state air quality regulations currently curb the release of methyl bromide emissions.
Introducing new requirements to reduce the concentration of emissions at four operating facilities in North Carolina will impact an estimated 12 jobs. An estimated 150,000 people in North Carolina may be currently exposed to methyl bromide emissions in excess of EPA chronic health guidelines.
Also, approximately 60-to-70 percent of the human population has a genetic variation that metabolizes methyl bromide into a more toxic compound inside the body, according to the DAQ report. This means an estimated 75,100 to 87,600 people living in close proximity to fumigation facilities in New Hanover County are exposed to methyl bromide emissions in excess of chronic health recommendations and also have the specific genetic variation that further toxifies the compound.
Recommended concentrations
A lack of reporting requirements, and therefore a lack of reportable data, means DAQ officials used extensive modeling techniques to arrive at emission estimates. Though the DAQ estimates 152,449 in North Carolina could be currently over-exposed to methyl bromide, it acknowledges a “high degree of uncertainty in this estimate due to the lack of exposure concentration measurements.”
Estimated concentrations of the compound at both New Hanover County facilities, according to the DAQ, show emissions could be occurring at levels far greater than the EPA’s chronic inhalation level.
Methyl bromide fenceline concentrations range from an estimated 0.61 to 24 milligrams per cubic meter at the fenceline of the New Hanover County fumigation sites. At the minimum and maximum fenceline dispersal levels modeled at the River Road facility are respectively 1,414 times and 4,805 times higher than the chronic EPA level (at the Port facility, emissions are estimated to be occurring 122 and 885 times higher than the EPA level at DAQ’s estimated minimum and maximum dispersal models).
“Control technology would reduce emissions of methyl bromide by at least 90 percent, which would be a reduction of approximately 45 tons of methyl bromide per year from the existing facilities,” The DAQ’s report concludes. “This rule would also reduce the fenceline concentration from an average of 0.515 to less than 0.005 milligrams per cubic meter, a reduction of nearly 99 percent.”
DAQ is recommending the Environmental Management Commission (EMC) adopt the EPA level of .005 milligrams per cubic meter, based on human chronic exposure level.
However, the EMC is requesting public comment on a value within a range of AALs higher than DAQ’s recommendation. Empowered to adopt new statewide regulations, the commission is considering an AAL value of .078 milligrams per cubic meter — 15.6 times higher than DAQ’s recommendation. The higher measurement represents a minimal risk level established by the Agency for Toxic Substances and Disease Registry in 2018.
Public comment
The EMC opened a public comment period on the proposed changes June 17 which will remain open until Friday. Comments can be:
- Emailed to daq.publiccomments@ncdenr.gov with “Log Fumigation” set as the subject line.
Catch up on the public notice for the rule changes and read DAQ’s May 2019 fiscal note, April 2019 Risk Analysis fore more information.
Send tips and comments to Johanna Ferebee at johanna@localvoicemedia.com
