Posted by on February 12, 2013 - 2:50pm

More intense sunlight exposure was linked with a decreased incidence of rheumatoid arthritis (RA) among women in the original Nurses' Health Study (NHS), although the more common use of sunscreen likely weakened the association in a later cohort, researchers found.   Rheumatoid arthritis, or RA, is a form of inflammatory arthritis and an autoimmune disease. For reasons no one fully understands, in rheumatoid arthritis, the immune system – which is designed to protect our health by attacking foreign cells such as viruses and bacteria – instead attacks the body’s own tissues, specifically the synovium, a thin membrane that lines the joints. As a result of the attack, fluid builds up in the joints, causing pain in the joints and inflammation that’s systemic – meaning it can occur throughout the body.

In the original Nurses' Health Study, which began in 1976, women (ages 30 to 55) living in states with the highest ultraviolet B (UVB) intensity had a 21% lower risk for RA compared with those living in states with low UVB levels according to Elizabeth Arkema, PhD, and colleagues from Harvard University.

But in NHSII, initiated in 1989 in women ages 25 to 42, no significantly lower risk was seen, the researchers reported online in Annals of the Rheumatic Diseases.

"The later birth cohort of NHSII participants (born between 1946 and 1964) were more likely aware of the dangers of sun exposure and, perhaps, had more sun-protective behavior, making residential UVB not as good a proxy for actual sun exposure in NHSII," they suggested.

Epidemiologic studies have found a correlation between an increased incidence of RA and other autoimmune diseases with higher latitude (more northern) areas  of residence.  In addition, experimental studies have demonstrated that UVB may suppress the immune system (which overacts in RA).  Exposure to UVB also increases vitamin D synthesis in the skin, which, in turn, has altering effects on the immune system properties.

UVB flux is a measure that reflects exposure intensity based on altitude, latitude, and typical cloud cover patterns, and is expressed in Robertson-Berger units. This measure shows considerable variability in the U.S., ranging from 196 R-B units in sunny states such as Arizona and Hawaii to only 93 units in Oregon and Alaska.

Information on residence, health, diet, and lifestyle was acquired every 2 years from participants in both cohorts.

Similar findings of decreased risk for high exposure in NHS though not in NHSII were seen both for exposure levels at birth and at age 15.  It thus remains unclear if the important window for UVB exposure is in childhood or adulthood. Further analyses found no significant heterogeneity according to skin type, vitamin D intake, or physical activity and body mass index.

These findings add to the increasing evidence that more intense sun exposure lowers the risk of RA, the researchers stated.  "The mechanisms are not yet understood, but could be mediated by cutaneous production of vitamin D and attenuated by use of sunscreen or sun avoidant behavior," Arkema and colleagues wrote.  They called for additional research to explore UVB dose intensity and timing of exposure.

EDITOR's NOTE:   While the link to skin cancer and UVB exposure is well known, the increased use of sunscreen raises other health concerns that may require new approaches to find a "balance" so the benefits of  a little sunshine are not totally lost.
Source reference:
Arkema E, et al "Exposure to ultraviolent-B and risk of developing rheumatoid arthritis among women in the Nurses' Health Study" Ann Rheum Dis 2013; DOI: 10.1136/annrheumdis-2012-202302.


Posted by on July 20, 2012 - 10:59am

A recent study published in Environmental Science & Technology tied a group of chemicals called benzophenones to an increased risk of endometriosis.  The study measured the amount of benzophenones in the urine of 600 women who were tested for endometriosis.  One particular benzophenone, benzophenone-1, showed a significant association with the condition.  Compared to women with low levels, women who had the highest concentration of this chemical in their urine showed a 65% greater chance of having the condition.  In a separate study, the CDC found benzophenones in the urine of 97% of people tested.  With one in ten women having endometriosis, benzophenone-1 may be the cause.

Benzophenones protect against UV light.  In small quantities, like nail polish, it stabilizes compounds that are stored in clear containers.  When used in a higher concentration, such as on the skin, it becomes a good sunscreen.  Benzophenone-1 in particular can be produced from oxybenzone (or benzophenone-3), a chemical penetration enhancer found in sunscreen, when the body breaks it down.

Interestingly, the CDC also linked benzophenone-3 to many other health issues such as allergies, hormone disruption, cell damage and low birth weight in female babies.  Among sunscreen, the chemical can also be found in facial cleansers/treatments, lip balm, lipstick, anti-aging creams, conditioners and perfume.

Endometriosis, a gynecological condition, occurs when tissue from the uterus grows outside of the uterus instead of inside it.  The tissue can start to grow in other places such as into the abdomen, outside the ovaries and around the fallopian tubes.  It thickens and sheds simultaneously with the tissue inside of the uterus during the menstrual cycle.  The condition causes pain, irregular bleeding, scarring and can cause infertility.

The group of chemicals mimics estrogen, and while researchers cannot definitively pinpoint the cause of the condition, they do know that estrogen enhances the condition.  Treatment usually involves medications to lower the amount of estrogen in the body.

The Personal Care Products Council, which represents cosmetics manufacturers, said that the study was weak and unconvincing and should not be a deterrent from sunscreen or safe-sun practices.  The group says the study did not ask participants if (or how much) sunscreen they wore, therefore they couldn’t attribute the results directly to sunscreen.

Conversely, women in California had higher concentrations of the chemical when tested during the summer, suggesting that sunscreen is the culprit, according to Sonya Lunder, MPH of the Environmental Working Group.  The CDC found similar results in light-skinned women who were tested, further confirming Lunder’s theory.

Many of the findings seem conflicting. The best advice may be to find a sunscreen without the chemical, such as one that is mineral-based, containing zinc oxide or titanium dioxide.  These varieties block the sun naturally, so you can protect yourself against both the condition and the harmful UV rays.


Sunscreens without Oxybenzone:

Natural Sun SPF 30 Sunscreen for Active Lifestyles

Oat Protein Sunscreen SPF 30 by Kiss My Face

SPF 30 Sunscreen by Vanicream


Read more about the topic here or here.


Posted by on August 3, 2011 - 8:55am

Even if sunscreens say they’re waterproof, they’re not. Sunscreens can wash off with sweat, or just being in the water. When this happens, their sun protection washes off, too, leaving users at greater risk for burns, premature skin aging and possibly even skin cancer.

So the Food and Drug Administration has set new rules to help people know what they’re getting and when to use it. FDA dermatologist Jill Lindstrom:

``Sunscreens may only use the term `water resistant,’ and must clearly indicate how long water resistance actually lasts.’’

You might not see the change on the labels just yet because the rule is new – it’ll take effect by the summer of 2012 – so there’s a lot of product on the shelves that doesn’t have the information.

Learn more at