Immediate Pigment Darkening (IPD)

Star rating system

In the UK and Ireland, the Boots star rating system is a proprietary in vitro method used to describe the ratio of UVA to UVB protection offered by sunscreen creams and sprays. Based on original work by Prof. Brian Diffey at Newcastle University, the Boots Company in Nottingham, UK, developed a standard method which has been adopted by most companies marketing these products in the UK. The logo and methodology of the test are licensed for a token fee to any manufacturer or brand of sunscreens that wishes to use it, provided the products to which the logo is applied perform to the standard claimed. It should not be confused with SPF, which is measured with reference to burning and UVB.

One-star products provide the least ratio of UVA protection; five-star products are best. The method has recently been revised in the light of the Colipa UVA PF test, and with the new EU recommendations regarding UVA PF. The method still uses a spectrophotometer to measure absorption of UVA vs UVB; the difference stems from a requirement to pre-irradiate samples (where this was not previously required) to give a better indication of UVA protection, and of photo stability when the product is used. With the current methodology, the lowest rating is three stars, the highest being five stars.

In August 2007, the FDA put out for consultation the proposal that a version of this protocol be used to inform users of American product of the protection that it gives against UVA.

Sun Protection Factor (SPF)

The SPF of a sunscreen is a laboratory measure of the effectiveness of sunscreen — the higher the SPF, the more protection a sunscreen offers against UV-B (the ultraviolet radiation that causes sunburn).

The SPF is the amount of UV radiation required to cause sunburn on skin with the sunscreen on, relative to the amount required without the sunscreen. So, wearing a sunscreen with SPF 50, your skin will not burn until it has been exposed to 50 times the amount of solar energy that would normally cause it to burn. The amount of solar energy you are exposed to depends not only on the amount of time you spend in the sun, but also the time of day. This is because, during early morning and late afternoon, the sun’s radiation must pass through more of the Earth’s atmosphere before it gets to you. In practice, the protection from a particular sunscreen depends on factors such as:

* The skin type of the user.
* The amount applied and frequency of re-application.
* Activities in which one engages (for example, swimming leads to a loss of sunscreen from the skin).
* Amount of sunscreen the skin has absorbed.

The SPF is an imperfect measure of skin damage because invisible damage and skin aging are also caused by ultraviolet type A (UVA, wavelength 320 to 400 nm), which does not cause reddening or pain. Conventional sunscreen blocks very little UVA radiation relative to the nominal SPF; broad spectrum sunscreens are designed to protect against both UVB and UVA. According to a 2004 study, UVA also causes DNA damage to cells deep within the skin, increasing the risk of malignant melanomas. Even some products labeled “broad-spectrum UVA/UVB protection” do not provide good protection against UVA rays. The best UVA protection is provided by products that contain zinc oxide, avobenzone, and ecamsule. Titanium dioxide probably gives good protection, but does not completely cover the entire UV-A spectrum, as recent research suggests that zinc oxide is superior to titanium dioxide at wavelengths between 340 and 380 nm.

Owing to consumer confusion over the real degree and duration of protection offered, labeling restrictions are in force in several countries. In the EU sunscreen labels can only go up to SPF 50+ (actually indicating a SPF of 60 or higher) while Australia’s upper limit is 30+. The United States does not have mandatory, comprehensive sunscreen standards, although a draft rule has been under development since 1978. In the 2007 draft rule, Food and Drug Administration (FDA) proposed to institute the labelling of SPF 50+ for sunscreens offering more protection. This and other measures were proposed to limit unrealistic claims about the level of protection offered (such as “all day protection”).

UV-B sunlight spectrum (on a summer day in the Netherlands), along with the CIE Erythemal action spectrum. The effective spectrum is the product of the former two.

The SPF can be measured by applying sunscreen to the skin of a volunteer and measuring how long it takes before sunburn occurs when exposed to an artificial sunlight source. In the US, such an in vivo test is required by the FDA. It can also be measured in vitro with the help of a specially designed spectrometer. In this case, the actual transmittance of the sunscreen is measured, along with the degradation of the product due to being exposed to sunlight. In this case, the transmittance of the sunscreen must be measured over all wavelengths in the UV-B range (290–320 nm), along with a table of how effective various wavelengths are in causing sunburn (the erythemal action spectrum) and the actual intensity spectrum of sunlight (see the figure). Such in vitro measurements agree very well with in vivo measurements. Numerous methods have been devised for evaluation of UVA and UVB protection The most reliable spectrophotochemical methods eliminate the subjective nature of grading erythema.

Mathematically, the SPF is calculated from measured data as

where E(λ) is the solar irradiance spectrum, A(λ) the erythemal action spectrum, and MPF(λ) the monochromatic protection factor, all functions of the wavelength λ. The MPF is roughly the inverse of the transmittance at a given wavelength.

The above means that the SPF is not simply the inverse of the transmittance in the UV-B region. If that were true, then applying two layers of SPF 5 sunscreen would be equivalent to SPF 25 (5 times 5). The actual combined SPF is always lower than the square of the single-layer SPF.

Measurements of UVA protection – Persistent Pigment Darkening (PPD)

The Persistent Pigment Darkening (PPD) method is a method of measuring UVA protection, similar to the SPF method of measuring UVB light protection. Originally developed in Japan, it is the preferred method used by manufacturers such as L’Oreal.

Instead of measuring erythema or reddening of the skin, the PPD method uses UVA radiation to cause a persistent darkening or tanning of the skin. Theoretically, a sunscreen with a PPD rating of 10 should allow you to endure 10 times as much UVA as you would without protection. The PPD method is an in vivo test like SPF. In addition, Colipa has introduced a method which, it is claimed, can measure this in vitro and provide parity with the PPD method.

The UVA seal used in the EU

As part of revised guidelines for sunscreens in the EU, there is a requirement to provide the consumer with a minimum level of UVA protection in relation to the SPF. This should be a UVA PF of at least 1/3 of the SPF to carry the UVA seal. The implementation of this seal is in its phase-in period, so a sunscreen without it may already offer this protection.

Baby Sun Skin Care for the Summer

The hot days of summer are getting more intense with every year. Especially if you’re in the Northeast where we have a a sun-driven heatwave. Regardless of what zone you live in, smart skin protection is the best medicine to keep your child skin safe in the sun.

You probably remember your first sunburn and maybe even your latest one because it’s so easy for adults to splash sun screen on their kids, and forget to put it on themselves.  As you know, infant skin burns much more easily than adult skin. That’s why it’s important to take extra care with infants and toddlers when they are out in the sun.

UV Rays
It’s no secret that the depletion of the ozone layer has changed our way of thinking about sun protection. There is no doubt that the sun rays today are stronger and more intense those of 60 years ago.

Extended exposure to ultraviolet rays from the sun causes skin damage and premature aging. However, it is important to remember that sunlight is important to good health. Small amounts of ultraviolet rays stimulate the body to produce vitamin D, an essential vitamin for good health. Deficiency of vitamin D is a serious health concern and leads to conditions such as rickets in children. In short, moderate sun is healthy, but sunburns are not.
Too much exposure to sunlight can result in immediate pain and long-term harm. Without getting too scientific here, sunburn is caused by extended exposure to the sun’s ultraviolet rays. Short-term results can be pain, allergic reactions and heat stroke.  In the long term, researchers say that victims of sunburn can suffer from lupus, cataracts, premature skin aging and an increased risk for skin cancer.

Skin Type
A person’s sensitivity to the sun is related to his or her skin type. An individual’s skin type determines how easily that person can become sunburned. Those with fair skin, freckles, blue eyes and/or blonde or red hair sunburn much easier than those with darker skin, eyes and hair.

Children younger than 6 years of age and adults older than 60 years are at an increased risk for sunburn. Skin type affects how easily you become sunburned. People with fair or freckled skin, blond or red hair, and blue eyes usually sunburn easily. Your age also affects how your skin reacts to the sun.

Young Skin is Sensitive
The skin of children under age 6 and adults over age 60 is more sensitive to sunlight. Premature aging from sunlight can affect people of all skin shades. A sunburn can be caused by the sun or by artificial tanning sources, including tanning beds and sun tanning lights. You can even get sunburned not only in the summer, but also in the winter.

Here are some basic sun care tips:

• Sunlight is most intense between 11 a.m. and 3 p.m., so avoid exposure during these times
• Avoid exposing babies younger than six months of age to direct sunlight
• Dress your child in light, loose clothing that covers the whole body
• Use a sun hat or bonnet, and keep the sunshade up on the stroller up This is good advice for young babies
• Toddlers often resent the restrictions of clothing, and feel it’s best to run around naked. For these free little spirits, use a gentle, natural sunscreen with organic ingredients, available at your health food store
• Slather on sunscreen generously and reapply, even on cloudy hazy days
• Never put sunscreen too close to children’s eyes or on their hands, as they might rub their eyes and cause irritation
• Keep your child and yourself well hydrated. Keep water bottles handy or nearby
• Bring a beach umbrella to the beach or park(if there are no shady trees nearby)

Have fun in the sun this summer, but do take care of the tender skin.

Top Five Sun Care Picks From EWG

We’ve established the importance of sun care, for your baby, and the entire family. At this time there aren’t any safety standards set by the FDA for sunscreens. So it is important for parents to know what they are truly rubbing into their baby’s bodies. A good example of the standards set for our sunscreens is the use of PABA (”a skin damaging chemical”, EWG) that was more widely used in the past. It still is, however, since there was an outcry from consumers with allergic reactions, companies use it less.

The bottom line is that we parents need to be aware that some sunscreens may be potentially more harmful than good. “Studies show that some traditional sunscreens like oxybenzone and octinoxate definitely absorb into healthy skin – in large amounts according to some studies – and act like estrogens in the body, raising risks for breast cancer, and showing effects like hormone-driven uterine damage in other studies”. 1

Take a look at your current sunscreen and you will probably find one of these ingredients, if not both. There is also some controversial concern with the micro sized (nanosize) titanium and zinc. Are these particles so small that they can absorb through the skin and into our blood stream? For now it is considered safe (as long as the particles aren’t too small) on healthy skin. A good way to test is this, if the sunscreen rubs clear onto your baby’s skin, it is nanosized. If it rubs on with some white, the particles are not too small.

Below we’ve listed the top five choices according to the Environmental Working Group. We always suggest, however, to do your own homework and then you can make an educated decision as to what is right for your family.

Environmental Working Groups Safest Sunscreen Picks

1. Keys Soap Solar Rx Therapeutic Sunblock
2. Trukid Sunny Days Facestick Mineral Sunscreen UVA/UVB Broad Spectrum
3. California Baby Sunblock Stick No Fragrance
4. Badger Sunscreen
5. Marie Veronique Skin Therapy Sun Serum