EPA Report: 22 Million Cataract Cases Will Be Prevented by Stronger Ozone Layer Protection

Submitted by Norm Roulet on Fri, 07/30/2010 - 13:49.

WASHINGTON -- The U.S. Environmental Protection Agency marked the beginning of Cataract Awareness Month by announcing a new peer-reviewed report predicting that more than 22 million additional cataract cases will be avoided for Americans born between 1985 and 2100 due to the Montreal Protocol. The environmental treaty, signed by 196 countries, was designed to reduce and eventually eliminate ozone depleting substances. Too much UV radiation not only increases the risk for skin cancer, but also increases the risk for cataracts -- a clouding of the eye’s lens that affects more than 20 million Americans age 40 and older.

“Since the 1970s, we have prevented millions of skin cancer cases and deaths through our work protecting the ozone layer,” said Gina McCarthy, assistant administrator for EPA’s Office of Air and Radiation. “I am excited to kick off Cataract Awareness Month by announcing that the science has now enabled us to estimate our impact on cataracts.”

Due to the success of the Montreal Protocol, the ozone layer is predicted to recover to pre-1980 levels after 2065. In the meantime, under a compromised ozone layer, more ultraviolet (UV) radiation reaches the Earth’s surface. While treatment for cataracts is widely available in the U.S., the costs are high, with direct medical costs estimated to be $6.8 billion per year.

For the first time, EPA is able to include data on cataract risk by gender and skin type in the report. However, all people, regardless of gender and skin type, are at risk for cataracts. This is why it is important for adults and children to use eyewear that absorbs UV rays and to wear a wide-brimmed hat.  

The following changes in vision may be signs of cataracts:

·         Blurred vision, double vision, ghost images, the sense of a "film" over the eyes

·         Lights seem too dim for reading or close-up work, or feeling "dazzled" by strong light

·         Changing eyeglass prescriptions often, and the change does not seem to help.


Information on the report:



More information on eye damage: http://www.epa.gov/sunwise/doc/eyedamage.pdf.


More information on the Montreal Protocol:  http://www.epa.gov/ozone/intpol/



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Dave Ryan

Ryan [dot] dave [at] epa [dot] gov





July 30, 2010




Prepared for: Stratospheric Protection Division - Office of Air and Radiation - U.S. Environmental Protection Agency - Washington, D.C. 20460

Prepared by: ICF International, 1725 Eye Street, NW, Washington, DC 20006

July 30, 2010

Executive Summary

Human-made ozone-depleting substances (ODS) such as chlorofluorocarbons (CFCs), halons, methyl bromide, and hydrochlorofluorocarbons (HCFCs) reduce the ozone concentration in the Earth’s stratosphere. The ozone layer acts like a protective shield, so damage to it significantly increases the amount of ultraviolet (UV) radiation reaching the Earth’s surface. More UV means more adverse human health effects, like skin cancer and cataract. The 1987 Montreal Protocol on Substances that Deplete the Ozone Layer (Montreal Protocol) is an international agreement in which governments have acknowledged the harm and agreed to phase out production and import of specific ODS.

The U.S. Environmental Protection Agency (EPA) uses the Atmospheric and Health Effects Framework (AHEF) to assess the human health benefits in the U.S. associated with reducing emissions of ODS under the Montreal Protocol and its amendments and adjustments. Previously, the AHEF estimated the skin cancer cases and deaths avoided. This report shows that the AHEF now has the capability to model avoided cataract cases.

The updates that enabled AHEF to model cataract incidence include:
    •    Improved spatial resolution;
    •    Updated information on the biological effects of UV radiation, including dose-
         response data by skin type and gender;
    •    More recent epidemiological data; and
    •    Improved calculation of the solar zenith angle.
These updates increase model accuracy and improve model output. This report discusses these updates, improvements, and future work.

EPA uses AHEF to examine how health effects change under different ODS control policy scenarios either relative to the 1979-1980 baseline, or compared to one another. For example, this report estimates that the strengthening of the original Montreal Protocol through the Montreal Amendments of 1997 will result in more than 22 million additional new cataract cases avoided for Americans born between 1985 and 2100. This finding illustrates how reducing ODS leads to increases in stratospheric ozone concentrations, thereby reducing cataract incidence. The results further demonstrate two trends when comparing less protective policies for protecting the ozone layer to more protective policies. First, U.S. counties with many residents older than age 55 have a demonstrably higher cataract incidence than neighboring counties with fewer residents over age 55. Second, because ozone depletion occurs more significantly at higher latitudes, residents of northern counties experience a higher relative increase in exposure to UV radiation than do residents of southern counties.

The sensitivity analysis found that changing the biological amplification factor (BAF) as a function of skin type and gender was not highly influential. Overall, the BAFs -- the dose-response relationship between UV radiation intensity and cataract cases caused -- were the greatest source of uncertainty, followed by the choice of action spectrum that relates UV exposure to incidence of cataract. EPA plans additional updates to AHEF to further improve its capabilities. The emissions scenarios will be updated to reflect current assumptions regarding ODS emissions estimates, including the development of a new emission scenario that represents the Montreal Protocol as adjusted in 2007 and to calculate the health benefits associated with this more aggressive phase out of HCFCs. EPA may also examine avoided costs, and may be able to enhance the model’s exposure estimates considering behavior, solar zenith angle, and age.


Cataract is a clouding of the eye’s naturally clear lens. Mostly, cataracts appear as we grow older, usually after age 40. Over time, cataract formation in one or both eyes can cause vision impairment and blindness. Age-related cataract has a number of potential causes, but lifelong exposure to ultraviolet radiation from the sun likely plays a significant role. In the 2008 update to the Vision Problems in the U.S. report, the
National Eye Institute and Prevent Blindness America estimated that cataract affects more than 22 million people, one in six over the age of 40, in the United States. The only treatment for cataract is removal of the clouded natural lens. Most cataract patients receive an artificial lens, called an intraocular lens (IOL) implant in what is typically a safe and highly effective outpatient procedure. But this treatment can be costly for individuals and for society. Prevent Blindness America estimated in its 2007 Economic Impact of Vision Problems report that the direct medical cost of cataract treatment for Americans over the age of 40 totaled $6.8 billion annually. This figure does not include lost productivity from reduced labor force participation and health utility costs related to distress, pain, depression, mobility and social limitations as measured by quality-adjusted life years. These direct and indirect costs will only increase as the U.S. population ages and cataract becomes even more prevalent. The next edition of Vision Problems in the U.S., to include estimates based on 2010 U.S. Census data, is expected to
reflect this trend.

The average direct outpatient cost of cataract treatment is $1,268 per patient. For inpatient treatment, the cost rises to $5,689 per patient. Consequently, every case of cataract delayed or avoided entirely will return savings to individuals, our health care delivery system, and society as a whole, not to mention the potential impact in improved quality of life for those who do not have to face vision impairment or surgery.

Protecting the Ozone Layer Protects Eyesight – A Report on Cataract Incidence in the United States Using the Atmospheric and Health Effects Framework Model offers an important reminder of the link between the intensity of ultraviolet radiation and cataract incidence. At Prevent Blindness America, we fully support the Environmental Protection Agency in its efforts to increase public awareness of the consequences for our eye and vision health resulting from UV exposure and the estimated health benefits of domestic and international policies to reduce levels of ozone-depleting substances in the atmosphere. Without the Montreal Protocol on Substances That Deplete the Ozone Layer and its amendments and adjustments, the economic and social burden of cataract might well have been much higher for our nation.

As the report emphasizes, cataract is primarily an age-related phenomenon, with risk factors that may vary for individuals depending on where they live, their level of outdoor activity, and the extent to which they take steps to protect their eyes from UV radiation throughout their lives. Protecting the Ozone Layer Protects Eyesight - Cataract

Incidence in the United States Using the Atmospheric and Health Effects Framework Model sets the stage for additional research to demonstrate the direct economic and societal benefits of ozone layer protection and enables future efforts to tailor more precise public health messaging about UV eye protection that may avoid many more cases of cataract for generations of Americans in the years and decades to come.

Hugh R. Parry
President & CEO
Prevent Blindness America