top of page
  • Writer's pictureTom Petersen

Treating Imports at Philadelphia's Ports

Updated: Aug 30, 2023

Guest columnist, Emma Fried-Cassorla, is a recent graduate from the University of Pennsylvania’s Master’s of Environmental Studies program. During her time in the program, she concentrated on urban environmental issues including stormwater management, brownfield revitalization, and sprawl. Her thesis focused on the environmental impacts of the Philadelphia Port’s movement of produce. Traditionally, environmentalists have focused on issues stemming from the port’s use of diesel-powered trucks and cranes, or pollution caused by ballast water, but she chose to examine the impacts that the port’s fumigation management practices have on the ozone layer. In addition to her academic life, she is a research associate and lab manager in a neuroscience lab at the University of Pennsylvania. Outside of this, Emma runs a website dedicated to celebrating the many unique places that this city has to offer through the words of local residents ( She is currently looking to transition out of the academic science field and into a job that offers her the chance to address Philadelphia’s land use issues. She can be reached at

One of the Philadelphia port’s specialties is importing perishable commodities. Meat, dairy, fruits and vegetables enter the regional and national economy through terminals lining the Delaware River. As trade becomes more globalized, and specifically trade in fruits and vegetables, countries take on the risks of importing unwanted pests.

Non-native insects, bacteria, fungi, and other organisms can hitch rides across oceans on or within these commodities. Upon arrival in a country, newly introduced species have an opportunity to take hold in environments lacking natural predators. They may have competitive advantages that allow them to thrive at the expense of native species’ survival. They may also carry diseases detrimental to indigenous populations. In any of these situations, an introduced pest can flourish unchecked, resulting in billions of dollars in damages and treatment expenses. To guard against these occurrences, countries have set up phytosanitary organizations, such as the United States Department of Agriculture’s Animal and Plant Health Inspection Service (USDA-APHIS). The role of these organizations is to impose limits on imports, to investigate and mitigate outbreaks, and to establish treatments to protect against these unwanted introductions.

In the United States, treatment options are either chemical or physical in nature. When a commodity arrives at a port of entry, it is subject to heat or cold treatments, fumigations, or irradiation to rid it of possible hitchhikers. The type and duration of treatment depend on the commodity, the potential pest, and the country of origin. Some fruits and vegetables require no treatment while others require them as a mandate of entry at the port. This means that the commodity is treated at every entry irregardless of whether pests are found. In other cases, pests are removed according to U.S. protocols in the exporting country before being shipped. In these situations, the produce is inspected upon arrival to determine whether it should be allowed to pass, whether it needs to be retreated at the American port, or whether it should be returned to the country of origin.

The Philadelphia port has a warehouse dedicated to methyl bromide (MB) fumigations, the most commonly used chemical fumigant. MB has properties that make it ideal for widespread use on commodities for consumption. It is a generalized biocide that can kill organisms across the spectrum. Its chemical properties make it gaseous at standard temperature and pressure, and highly volatile, which means it breaks down rapidly into non-toxic byproducts. The chemical residues on fumigated products are below levels of concern, a requirement for human consumption.

However, the chemical properties that confer upon it its strength as a fumigant also make it a powerful ozone depleting substance (ODS). ODS, also referred to as halogens, are gases that can drift into the stratosphere where they react with high-energy ultraviolet light to free their chlorine, bromine or iodine atoms. Once released, these atoms catalytically react with and destroy ozone. The stratospheric ozone layer provides a barrier between the sun’s harmful ultraviolet radiation and the earth’s surface. The destruction of this layer has critical implications for human health, ecological functioning, biogeochemical cycles, air quality, and synthetic material stability.

In 1990, the Montreal Protocol added MB to the list of chemicals to be phased out of use because of their ozone depleting properties. This treaty has been globally ratified, with signatories agreeing to eliminate the use of these listed chemicals. It has been estimated that eliminating ODS consumption will prevent 6.3 million cases of fatal skin cancers, 300 million non-fatal skin cancer cases and 27.5 million cataracts in the U.S. (EPA, 1999). The avoided human heath and environmental damages are approximately $4.3 trillion dollars in the U.S. alone. Despite the potential ramifications from continued ODS use, there are some exemptions that remain for MB. These exceptions recognize that there are currently no viable alternatives for MB in certain situations. It is still produced and consumed for import and export purposes and for agronomic needs. In many of these cases replacing it would be economically unfeasible. Thus, MB use remains pervasive.

Data provided by the Philadelphia Regional Port Authority (PRPA), USDA-APHIS, and the U.S. Census Bureau was analyzed in order to establish a relationship between the Port’s use of MB and it’s corresponding effects on the ozone layer. In 2011, approximately $1.2 billion worth of fruits and vegetables flowed through the Philadelphia port. Not all of these commodities received treatment upon entry, but some, such as Chilean grapes, required methyl bromide fumigation because of the threat posed by potential hitchhiking organisms.

The products arriving in Philadelphia that required methyl bromide as a condition of entry totaled $346 million. They comprised 29% of all imported fruits and vegetables. In that year, the Philadelphia port used 185,000 lbs of MB to fumigate commodities that required treatment either as an entry mandate or that were found to be infested upon inspection. The port contributed 0.3% of global industrial anthropogenic MB emissions and 0.04% of global MB emissions. This represents 0.01% of total ODS in the atmosphere when all gases are normalized to chlorine.

Philadelphia terminals received 40% of the $1.5 billion of Chilean fruits and vegetables imported nationally in 2011. The majority of the port’s fumigations targeted these particular commodities. The fumigation of grapes, predominantly Chilean grapes, represents 90% of the total MB applied at the port and 60% of the national aggregate. Of all the imported produce subjected to mandatory MB treatment, Chilean imports represent 99.7% of the total value. This is equivalent to $345 million worth of fruits and vegetables.

Chilean produce requires fumigation because of the high probability that it carries one or more invasives, such as: the Chilean False Red Mite, the Mediterranean Fruit Fly, or the European Grapevine Moth. Each of these pests alone has the potential to cause billions of dollars in damages. While some alternatives have been identified to target certain organisms, USDA-APHIS has not approved a viable substitute to completely replace MB, nor one to properly kill or sterilize these particular pests.

Previously, most environmental concerns about the port focused on the regional air and water impacts. This report suggests a global effect that until now had not been quantified. While the port’s contribution is only a fraction of total ODS concentrations, the potential human health and environmental implications are significant. No law or treaty exists that bans MB use for quarantine purposes because it could essentially halt international produce trade. Also, no taxes or tariffs are in place to encourage reduced consumption. Therefore the port has no obligation or incentive to stop using MB or to limit Chilean grape imports. Until an alternative is found, the most that can be expected is a strict adherence to best management practices to guarantee the lowest emissions possible and thus minimize human and ecological repercussions.



bottom of page