Pollution from the Cruise Ship Industry

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By Guest Contributor Audrey Arnold, Environmental Scientist.

Since the advent of the modern recreational cruise in the early 1960s, the cruise industry has attracted millions of passengers drawn to luxurious voyages in exotic destinations. As the popularity of cruises has grown, so have concerns about the environmental consequences of the wastes produced by passenger liners. In particular, conservationists have become increasingly weary of the disposal of sewage and wastewater generated by these massive ships, and the resulting water pollution.

How Much Waste Is Produced?

Over 230 cruise ships are currently active around the world, and a ship carrying 3,000 passengers can produce 21,000 gallons of sewage waste (known as “black water”) every day. Some ships can carry as many as 8,000 passengers, more than doubling the amount of waste produced. A conservative estimate of the total amount of sewage produced by the cruise ship industry is 1 billion gallons per year; approximately eight times as much “gray water” from showers, laundry, and sinks is also produced.

Despite recreational cruises being a multi-billion dollar industry, over 40% of ships from 16 surveyed cruise lines rely on outdated wastewater treatment technologies. Poor waste treatment allows disease-carrying fecal matter, heavy metals, and other contaminants to be released into water bodies, often within close reach of sensitive ecosystems.

What Are the Health and Environmental Impact?

Human fecal matter within wastewater contains a variety of pathogens, including salmonella, E. Coli, and hepatitis.

These diseases can be spread through direct contact with contaminated water or through the consumption of seafood which has come into contact with the pathogens.

Beyond human health effects, the disposal of poorly-treated wastewater negatively impacts sea life and its environment. Coral, fish, and shellfish can suffocate due to excess nitrogen and phosphorus contained in detergents and soaps in gray water, while heavy metals can be directly toxic, affecting neurological and reproductive functions.

A Role in the Spread of Invasive Species

In addition to waste produced by passengers, the ships themselves require large amounts of water to remain functional. For example, bilge water, produced on the lowest part of the ship’s hull and originating in ships’ major engine bays, can include oil, grease, and other hydrocarbons. However, international regulations currently prevent water containing greater than 15 parts per million of oil and grease from being disposed of in open water; oil-water separators filter out hydrocarbons from bilge water until the pollutants in the water are within the allotted concentration. 

In addition, ballast water, which is pumped in and out to help maintain balance as the ship travels, is a known vector of invasive species, such as plants, algae, and bacteria. Strict regulations, a direct result of the known transport of invasive species, are also in place for ballast water. For example, ballast water intake and discharge must be logged, and water can only be discharged in proximity to its location of origin or further than 200 nautical miles from shore. However, improper or falsified logs have been known to occur, threatening the effectiveness of these regulations.

A Weak Regulatory Framework

Although some laws pertaining to the treatment of cruise ship wastewater exist, they are not as stringent as water sanitation laws which apply to land-bound industries. Currently, within three nautical miles of the coastline, all wastewater which is disposed of must first be treated; however, this law does not apply to wastes disposed of further from shore.  Although some cruise lines are making efforts to become more environmentally-conscious, there is still much progress to be made with respect to the treatment and disposal of wastewater.

Sources

EPA. Water: Vessel Water Discharge.

International Maritime Organization.

Oceana. Contamination by Cruise Ships, 2004.