THE LABEL SPF CANNOT BE USED TO ESTIMATE SAFE SUN EXPOSURE TIME

How SPF Testing Fails to Replicate Real Sunlight and its Impact on Your Health

North American consumers should not rely on label claims - whether it is the SPF or claims of UVA and Broad spectrum protection. Most of our brand name sunscreens would not pass European or Australian criteria for UVA-PF (UVA- Protection Factor) and their better standards for Broad Spectrum coverage. Proper and adequate UVA protection may be the most essential property for a sunscreen to actually prevent skin cancer and photoaging. The global market, particularly in North America is dominated by UVB- BIASED sunscreens with inadequate UVA protection, despite label claims saying ‘BROAD SPECTRUM’ UVA/UVB. Even the EWG (Environmental Working Group) recognizes this reality in their 2017 Sunscreen Report. More on this in my next BLOG. 

There are over 25 stakeholder and professional coalitions with Comprehensive Cancer Control (CCC) plans  that publicise a prevention strategy. Language may differ but they all focus on key elements of sun avoidance, never burn or tan from UV exposure, wearing protective clothing with a tight weave, wear UV protective sunglasses, and generously apply a sunscreen with sun protection factor (SPF) 15 or higher and both UVA/UVB protection. Sunscreen use is the weakest link in the protocol. Rising cancer rates show that the current approach has failed and critical analysis argues that ineffective UVB-BIASED sunscreens dominating the N.American market are a driving factor.  Australia where balanced sunscreens using better UVA filters are plenty,  are actually seeing skin cancer rates levelling off or falling in certain provinces. Two landmark studies from Australia show that effective sunscreens applied daily can potentially reduce all forms of skin cancer. In N. America the grim reality is otherwise:

• Skin cancer is now the most common cancer in the United States with the incidence essentially doubling for all skin cancers in 40 years,  and they now account for more than 50% of all human cancers - i.e. skin cancer cases outnumber all other cancers combined. 

• In 2017, over 160,000 Americans are expected to be diagnosed with melanoma, which is the leading cause of cancer death in women ages 25-30 and the second leading cause in women ages 30-35.  In ages 15-29, melanoma is the second most commonly diagnosed cancer. From 1970 to 2009, the incidence of melanoma increased by 8-fold among young women and 4-fold among young men. In the USA, one person dies of melanoma every 54 minutes (almost 10,000/year).  4000 Americans die in a year from Squamous Cell Cancer (SCC) .

Preventing sunburn (early effect) or UVA damage (early and late effects), and damage to the genetic and immune apparatus of the skin is the essence of effective photoprotection. The label SPF is supposed to quantify a sunscreen’s ability to prevent that early sign of sun damage. The SPF as measured by FDA and Health Canada mandated tests give a poor estimate of the sunscreen’s actual performance in sunlight. 

The premise that SPF can be used to plan your exposure time is based on several invalid assumptions. Recent studies confirm that the lab or label SPF is inaccurate, when compared to the real life value obtained in sunlight. The lamp used in calculations for label purposes, only emits 290-400 nm based on the false assumption that the erythema reaction was mediated only by UVR (UVB and UVA). Visible Light (VL at 400-740 nm)) and Infra-red (IR at beyond 740 nm)) could be responsible for up to 20-30 % of the erythema response. Sunlight has more UVA (up to  5X ) than the testing lamp emission. Industry and physicians continue to advise consumers that the SPF can be used to calculate the safe exposure time for protected skin outdoors. We know differently -  fair individuals mostly get sunburned with prolonged outdoor exposure or during tropical vacations, despite using high SPF sunscreens and stringently following all the re-application instructions.   Media reports in 2015-2017 from Consumer Reports, the BBC in the UK, CBS, NBC, and CNN in the USA, have all presented data that up to 50% of brand name sunscreens fail to achieve even 50% of their labelled SPF values. 

Science now confirms this travesty. The label SPF is inaccurate when compared to the real life value obtained in sunlight. A landmark study  presented at the 26th Annual Meeting of The Photomedicine Society (Orlando, Florida, February 2017), showed that  50 commercially available sunscreens with label SPF 50 or more had SPF values of 6-10  when measured in sunlight (Hughes S. and  Cole C.). No wonder, as testing lamp emission spectrum is far removed from that of actual terrestrial radiation, and the intensity used in testing is different from sunlight. The compliance factor also adds another real life problem as most  users apply < than the 2 mg/cm²  as done for the lab test. Scientists also now provide the principles in physics that explain why the SPF test cannot be accurate (Diffey B, Osterwalder U, 2017).  They report that labelled SPF, determined by in vivo assay using a UV solar simulator, overestimates the SPF that would be expected in natural sunlight.  Products labelled SPF50+ may not be able to achieve a protection against sunlight of more than 25-fold., or SPF 25. The popular interpretation of the SPF to mean how much longer skin covered with sunscreen takes to burn in sunlight compared with unprotected skin, can no longer be defended.

Any falsely high SPF reading can be further  manipulated by adding anti-redness agents (similar to aspirin) that artificially increases the MED (Minimal Erythema Dose) used to determine the SPF, for the sunscreen containing these anti-inflammatory chemicals. Sunscreens are replete with SPF boosters- bisabolol, niacinamide, salicylate compounds, and numerous others. This may be very harmful to a consumer. The false (often high SPF 50-100) values distort the reality of what protection to expect. If you are very fair – Type 1- always burns never tans- you may actually burn within 5 minutes with extreme sun exposure. An SPF 30 conveys the impression that it is safe to stay out for up to 150 minutes and SPF 50 for up to 250 minutes. A real life SPF 10 in sunlight means you should multiply your 5 minute burn time by only 10 for a safe 50 minute exposure, then get out the sun or re-apply your sunscreen liberally if you stay out longer. A boosted SPF is falsely elevated by interfering with the biologic endpoint or early warning signal of redness, the first sign of sunburn. It is no longer commensurate to the amount of radiation being prevented from reaching your skin,  but related to delayed redness. You are actually burning but have no way of knowing this as your early warning signal has been blunted. This false sense of security may make you remain outdoors i/o seeking shade. You will experience more sun damage and incur the risks of skin cancer and photoaging. This  is only related to UVB exposure - think of the damage resulting from the more harmful UVA radiation that you are now receiving in high levels, particularly since most N. American sunscreens have inadequate UVA-PF values.

• Use no more than half the label  SPF when calculating your outdoor exposure time, and if you are redhead or extremely fair use a factor of 10.
• It is better to use the other elements of a photoprotection strategy – avoid sun exposure, wear UV protective clothing, wear head gear and UV protective sunglasses etc. - to the extent you can, and use a sunscreen with a safe UVA filter like zinc oxide in adequate concentrations.
• The particle type sunscreens that use zinc oxide, titanium dioxide, encapsulated octinoxate, drometrizole trisiloxane (Mexoryl XL™), terephthalylidene dicamphor sulfonic acid (Ecamsule or Mexoryl SX™),  biscotrizole (MBBT or Tinosorb M™), bemotrizinol (BEMT or Tinosorb S™),  and others are large in size, sit on the skin avoiding any entry into blood and the various attendant risks. Only the first five are available in Canada. Mexoryl XL™ and SX™ are patented to L’Oreal and regrettably are usually combined with undesirable soluble hydrocarbon filters, which should be stringently avoided. All except titanium dioxide and encapsulated octinoxate are UVA filters, and when mixed with other safe UVB filters achieve dispersions of spectral homeostasis (balanced UVA/UVB protection). In this situation where a sunscreen behaves like a neutral density filter, the label SPF may be closer to the Real Life SPF value in sunlight.  Look for products that have > 20% zinc oxide alone, or 15 % with 7.5% titanium dioxide or encapsulated octinoxate. 
• For maximum protection and to avoid all the controversy on hormone disruption and environmental hazards, use only sunscreens  with particle based or large molecular weight filters in the right combination. The high UVA protection achieves that flat balanced protection where the ratio UVA-PF/SPF approaches 1, and the label SPF comes closer to the Real Life value in sunlight. Strictly avoid all small molecular weight soluble hydrocarbon filters – avobenzone, oxybenzone, homosalate, octisalate, octocrylene, regular octinoxate, and 4-methylbenzilidene camphor. All may enter blood and only avobenzone has any UVA attenuation. It still gives a significant UVB bias where up to 30% of UVA between 340-400 nm – the most damaging UV rays are transmitted to your skin.

© Denis K. Dudley MD, October 2017. All rights reserved.

9 Reasons Why Oxybenzone Might be One of the Most Dangerous Chemicals in Your House

As a former specialist in Maternal Fetal Medicine (MFM) and Reproductive Endocrinology, I believe the Endocrine Disrupting Chemicals (EDC’s) are already affecting human health and I stopped exposing my family some 30 years ago. Even if they were not harmful, soluble filters gain entry to blood, tissue and brain. In pregnancy they pass through the placenta and bind to the various hormone receptors in the embryo and fetus. This is a bad idea. The World Health Organization report confirms the serious threat that hormone receptors pose to humans and wildlife. What it does not say is the obvious corollary that in our society, soluble sunscreen filters and other small Molecular Weight (MW) sized chemicals smaller than 500 Daltons, like the preservative parabens, are the single most important source of exposure to EDCs.

  

Sunscreens and their role in our Health

Although hormone disruptors are affecting human reproductive and other endocrine systems, there is a simple way to avoid a major source of EDCs.   There is also a simple way to protect this and the next generation from rising skin cancer rates. 

There is a growing list of adverse effects linked to hormone disruptors that must include the soluble sunscreen filters – oxybenzone, avobenzone, homosalate, octisalate, octocrylene and others. 

Some of these adverse effects include the following reproductive disorders: 

• infertility
• polycystic ovarian syndrome
• endometriosis
• fibroids
• breast and uterine cancer
• prostate cancer
• oligospermia 
• male infertility

Non-reproductive disorders include:

• ADHD
• asthma
• Parkinson’s 
• Alzheimer’s
•  thyroid cancer

Each person should make their own choice between two classes of sunscreens. Either use a sunscreen with small molecular weight (MW) soluble filters less than 500 Daltons. They are absorbed through the skin to reach blood, tissue, and bind to some receptors in the brain. They also give incomplete or UVB-biased protection that may prevent sunburn but affords little (if any) protection against skin cancer and photo-aging, where UVA1 rays play the major role. Lack of efficacy is compounded by the risk of serious and often permanent adverse effects, due to hormone disruption and carcinogenicity. 

Alternatively, you can choose a balanced sunscreen with insoluble particle type filters with  a MW greater than 500 Daltons.  This prevents entry into the skin as the filter remains within the outer dead layer of skin. A short list of UV Filters meet this criteria: zinc oxide, titanium dioxide, encapsulated octinoxate, Mexoryl SX™, Tinosorb S™, Tinosorb M™, Parsol SLX™, iscotrizinol, octyl triazone, and bisdisulizole disodium.  Only the first 3 are readily available in North America. Often formulas with a good filter are ruined by use of a soluble filter. These particles give more UVA1 protection with balanced UVB/UVA or better protection, and have no possible adverse effects. A balanced sunscreen can lower your melanoma and non- melanoma skin cancer risk and is the best anti-aging measure.

It defies any sensible logic that a parent or expectant mother would select soluble filters if they knew that they attain blood levels and reach the fetus. It is perplexing to me that many physicians continue to recommend their use. Even industry and regulators cannot deny that they attain blood levels. They use the absurd defence that only a small amount is absorbed. No comfort for a small child or unborn fetus. They also ignore the critical fact that these organic compounds are fat soluble and will bioaccumulate in tissue. These filters also come with the instruction to re-apply them several times per day- this can only add to their bioaccumulation in our bodies. 

The Oxybenzone Black List

Benzophenone, otherwise known as oxybenzone, gives context to how the danger exists in our everyday lives. Here is an evidentiary blacklist of reasons why this chemical should be banned from personal care products:

#1: It's Ubiquitous

A 2008 CDC study showed that this chemical is found in 97% of Americans tested, both genders between age 6-70 years (Calafat 2008).  It is still used in 65% of sunscreens in N. America and in over 950 cosmetics, which may explain why it is so pervasive. Women and girls had higher levels of oxybenzone in their bodies than males likely due to differences in use of body care products including sunscreens.

 #2  It's In Our Bodies and Our Children's Bodies

Other studies confirm the CDC report on this insidious and alarming  concern that this  chemical absorbs through the skin in significant amounts. A previous biomonitoring study reported that 96% of 6 to 8 year old girls had detectable amounts of oxybenzone in their urine (Wolff 2007). An earlier study detected oxybenzone in the urine of all 30 adult participants (Ye 2005).

#3 We Absorb More than You Would Think

Studies on human volunteers indicate a wide variation in the level of oxybenzone absorbed into the body, with some individuals absorbing at least 9% of the applied dose, as measured in excretions in urine (Hayden 1997; Janjua 2004; Sarveiya 2004; Gonzalez 2006). Volunteers continued to excrete oxybenzone many days after the last application of the chemical, an indication of its tendency to accumulate in fatty tissues in the body (Gonzalez 2006).

#4 It Increases Absorption Rates of Other Potential EDC's

In addition to its ability to absorb into the body, oxybenzone is also a penetration enhancer, meaning it's a chemical that helps other chemicals penetrate the skin (Pont 2004).

#5 It Has Potential Safety Concerns for Pregnant Women

Mothers with high levels of oxybenzone in their bodies were more likely to give birth to underweight or small for gestational age baby girls (Wolff 2008).

#6 It Could Be Affecting Our Fertility

It was also cited in a NIH report last year as being an important factor in male infertility, according to a study by the National Institutes of Health and the New York state Department of Health’s Wadsworth Center. This study merely underscores what the Endocrine Society, The WHO and The United Nations Environmental Program, have been saying for a decade- that the entire group of about 1000 known hormone disruptors have adverse effects on human reproduction, along with other effects on endocrine function and neural signalling. None of these reports follow through with the deductive analysis that given the patterns of human exposure, it is likely that soluble UV filters represent the most important source of EDC exposure in a developed society. 

#7 It's a Potential Carcinogen 

Sunlight also causes oxybenzone to form free radical chemicals that may be linked to cell damage, according to 2 of 3 studies (Allen 1996; Serpone 2002; Hanson 2006). Hence this generation of reactive oxygen species (ROS) could be carcinogenic to skin- this filter could be involved with causing the cancer it is supposed to prevent.

#8 It has Environmental Effects

The Hawaiians Knew- Sign from 2001 from beach in Maui, Hawaii 

Oxybenzone is contaminating  marine environments – washing off swimmers and in  municipal, residential, and wastewater effluent from marine vessels. A 2015 report (Downs et al) confirms other studies over the past decade that oxybenzone is genotoxic, kills larvae of reproducing coral, and converts the planula from a motile to a sessile state by ossification, due to its action as a skeletal hormone disruptor. Coral reef contamination of oxybenzone in the U.S. Virgin Islands ranged from 75 µg/L to 1.4 mg/L, whereas Hawaiian sites were contaminated between 0.8 and 19.2 µg/L.  Oxybenzone poses a hazard to coral reef conservation and threatens the resiliency of coral reefs to climate change.

#9 It's an Allergen

Oxybenzone and its structural cousin avobenzone are now the leading causes of photocontact allergy (Warshaw 2012). Although this is an infrequent problem, it is just one more reason why this chemical should be banned from personal care products. Consumers and physicians should question its continued use.  In most cosmetics, it’s only used to prevent discolouration in the product. It is still used in over 950 cosmetics and sunscreens.

Are All Sunscreen Actives Created Equally?

All of the organic soluble filters with small molecules (MW in the 250-500 Dalton range or < 1 nm)  should be viewed with the same concern . Many physicians still spread the myth that nanoscale zinc oxide usually 70- 300 nm and titanium dioxide 20-140 nm are so small they should concern us. In the world of sunscreens nano is large – usually  40-600 X larger than the soluble filter group, and nanoscale or micronized particles never penetrate beyond the outer layer of skin. There is a principle in endocrinology – isoform function – whereby chemicals with the same structure likely bind to the same hormone receptor and generally have the same effects. Hence avobenzone and octisalate very likely exert the same toxic effects as oxybenzone and homosalate, known to be hormone disruptors.  Why would anyone defend their  continued use? They enter the blood and brain of any person , including the most vulnerable – the unborn fetus and young children. They give you incomplete protection that could be a factor in rising skin cancer rates, and there is ample evidence that they are hormone disruptors and carcinogens in some cases. Finally, there is the evidence they also affect the health of lower species and destroy our reefs.

The WHO published a 250 page evidence based review entitled “ State of the Science of ENDOCRINE DISRUPTING CHEMICALS 2012 “ representing a broad scientific consensus among the leading experts in related fields. This echoes the warnings in scientific reviews  from The Endocrine Society,  The European Commission and the European Environment Agency. These documents implicate EDCs as a concern to public and wildlife health. In addition, the European Society for Paediatric Endocrinology and the Pediatric Endocrine Society have put forward a consensus statement calling for action regarding endocrine disruptors and their effects. “Of special concern are effects on early development of both humans and wildlife, as these effects are often irreversible and may not become evident until later in life.  The Endocrine Society stated : The evidence for adverse reproductive outcomes (infertility, cancers, malformations) from exposure to endocrine disrupting chemicals is strong, and there is mounting evidence for effects on other endocrine systems, including thyroid, neuroendocrine, obesity and metabolism, and insulin and glucose homeostasis.

The WHO list about 800 possible hormone disruptors, most of whom have never been studied for their possible human effects. Avoiding exposure to the extent you can is important in protecting our children and their children. 

As a follow up, my daughter Sara recently posted a reasoned discussion on why all consumers need to be concerned about hormone disruptors on our company blog (click here to read). She presented a persuasive argument on why a prudent person would try to reduce their exposure to these chemicals that now intersect with our daily lives. She is a new mother, and I take comfort from knowing that our precious new person will have little or no exposure to the permanent, serious, and even transgenerational adverse effects of these chemicals. As parents and grandparents, we will be vigilant and do our utmost to prevent her having any exposure.  She also blogged about sunscreen use in her pregnancy (click here to read).

Why Current Sunscreens Are Failing the Public

Sunscreens have been in the news lately. I thought that it would be timely to focus this blog on the issues. The EWG has named Neutrogena as the number # 1  sunscreen brand to avoid in their 2015 annual “Hall of Shame” report. It has gone viral. However many other leading brands continue to use the soluble filters that attain tissue levels and are implicated as hormone disruptors and carcinogens. 

These filters include :

• oxybenzone, avobenzone, homosalate, octisalate, octocrylene, 4-methyl benzilidene camphor and regular octinoxate. 

Better and safer particle based insoluble filters include :

• zinc oxide, encapsulated octinoxate,  titanium dioxide, and Tinosorb S and Tinosorb M (still awaiting FDA and Health Canada approval)

Here is an excerpt from the EWG report naming Neutrogena as the number 1 sunscreen to avoid:

“The Environmental Working Group (EWG) has released their 2015 guide to sunscreen, and among the worst brands for sun protection is the number one culprit for toxicity and false advertising, Neutrogena.“Neutrogena’s advertising hype is further from reality than any other major brand we studied. It claims to be the “#1 dermatologist recommended suncare brand, yet all four products highlighted on Neutrogena’s suncare web page rate 7, in the red – worst – zone in our database,” says EWG.  Not only do many Neutrogena sunscreens contain harmful chemicals like oxybenzone and methylisothiazolinone –– but their advertised SPF levels of over 70 have been debunked by the U.S. Food and Drug Administration. According to the federal department, SPF levels max out at about 50. Europe, Australia and Japan have already banned brands from advertising SPF levels over 50. EWG states 80 per cent of Neutrogena sunscreens contain oxybenzone, “a hormone-disrupting sunscreen filter” and 33 per cent contain retinyl palmitate, “a form of vitamin A linked to skin damage”. 

Taking it a Step Further:

What the document does not say is that the entire class of soluble filters – benzophenone, homosalate and others likely have the same effects and that all the leading brands that use these filters are equally harmful. This would include most Johnson and Johnson, L’Oreal, Coppertone, Proctor and Gamble, Banana Boat products, and 85 % of available sunscreens (EWG Hall of Shame 2015). The same filters give UVB biased protection and do not prevent cancer and photoaging. They are likely a factor in rising skin cancer rates. There are a growing list of adverse effects like reproductive problems, autism spectrum disorders and ADHD linked to hormone disruptors that must include soluble sunscreen filters – oxybenzone, avobenzone, homosalate, octisalate, octocrylene and others.  Each person should make their own choice between two classes of sunscreens.  Either choose sunscreens with small molecular weight soluble filters that obtain tissue levels, give incomplete or UVB-biased protection  to prevent sunburn but little protection against skin cancer and photoaging, and probably have harmful effects due to hormone disruption and carcinogenic effects. The alternative is to choose a balanced sunscreen with insoluble particle type filters that remain on the skin,  give you balanced UVB/UVA or better protection, and have no possible adverse effects.

A Word on Recent Controversy:

CBS news just reported a Consumers Report from May 2015 that 11/34 sunscreens failed to achieve their SPF claims at only 16-70% of their labelled value. This mirrors another report from a consumer group in the UK reported on the BBC website that only 1 in 5 consumers in Britain understand that the SPF only predicts UVB or sunburn protection and are aware of  or understand that the Boots-Diffey star system of 1-5 stars is an index of UVA protection and the balance or ratio of UVA/UVB protection. The BBC also reported in May a consumer group testing of Boots and Hawaiian Tropic sunscreens in the UK, showed the majority did not meet their SPF claims. You do not need studies to prove this – just ask most fair-skinned consumers on holiday – most end up with a sunburn despite using the typical brand names and re-applying them every 2-3 hours as instructed. 

SPF values are manipulated by adding anti-inflammatory agents that do not extinct any UV radiation but decrease the redness on skin and mask the biologic marker and first warning signal for injury to the skin. The solar lamps in labs have a sharp fall at 370 nm and a cut-off of 400nm- unlike sunlight where the curve continues to rise. Studies measuring SPF in actual sunlight show that even high SPF sunscreens at 30-100 usually only attain 10-20% of their labelled SPF claims. It was reported at the Annual Photomedicine Meeting in San Francisco this year that as an example Neutrogena Ultra-Sheer SPF 65 had a SPF value of only 10 in sunlight. The MED responses were assessed by luminary dermatologists not a lab technician!

Ways Forward:

We have always said that using SPF, UVA-PF, and CW values to establish the level of protection is the regulatory hurdle to assure adequate sun protection- an SPF of 30-50, a UVA-PF of a minimum 10 for SPF 30 and a minimum of 17 for SPF to meet or exceed the EU criteria of a UVA-PF/SPF ratio >1/3, and a CW of >370 nm as the secondary measure of balanced protection. This should be expressed on a label as a global standard in a very easy and transparent system to understand for sun protection- minimal, medium, high, and very high.

We advocate that sunscreens be UVA dominant with the ratio as close to 1 as possible, given the new studies over the past 10 years that prove UVA is the main factor in cancer and aging. UVB produces superficial injury as a shorter wavelength and lower intensity- it initiates sunburn and the DNA damage cycle, and modulates the process. UVA1 produces deeper DNA injury in the dermis, produces local and systemic inhibition of the immune system, and completes the damage cycle for photoaging and cancer. The majority of mutations in the keratotic basal layer where most cancers arise are UVA fingerprint mutations (not UVB as previously assumed), from hallmark studies over the past decade. UVA does not vary with latitude, or time of day, is present on cloudy days, is 15 X more intense than UVB, penetrates car and window glass, and is a deeper penetrating longer wavelength. It is easier to decrease your UVB exposure than to hide from UVA. Over 40 years it was counter-intuitive for dermatologists to believe that UVB was the main culprit in cancer and photoaging. Most still do. 

The entire protection strategy that includes the use of UVB-biased sunscreens has failed as is evident from rising cancer rates. In N. America rising skin cancer rates are due in part to ineffective sunscreens with partial UV or UVB-biased coverage. 5 million NMSC cases in the USA now cost the health care system 8.1 billion (up from I million in 1987). In the UK skin cancer has shown an alarming increase of 40% in the past 4 years. In Canada rates rise at a steady 2-3% per annum and melanoma was the 2^nd fastest rising cancer in 2014-15. It is now the leading cause of cancer death in girls aged 15-30 years. Balanced UVA dominant sunscreens could reduce skin cancer rates in 4 decades- NMSC by up to 80% and melanoma by up to 55%.

Final Recommendations: 

Until Tinosorb S and Tinosorb M are approved by the FDA and Health Canada, the only filter or combination of filters in N. America that meet the requirements for safety and balanced protection are as follows:

·       Zinc oxide alone, zinc oxide plus titanium dioxide, or zinc oxide plus encapsulated octinoxate are safe among those available here. Mexoryl SX and LX are also molecules that are > the 500 Dalton rule for no percutaneous entry- both are owned by L’Oreal and are never used without other undesirable filters from the soluble group.

·       Any filter has to used after expert consideration of the absorption curve and transmission metrics, the concentration of each filter, and the proper dispersion of actives within inactive ingredients. The Honest Company (Jessica Alba) fiasco demonstrates this. They had a 20%  ZnO but complaints of poor esthetics were an issue. They reduced the ZnO to 9% - no other active. Anyone with a basic knowledge of Photometrics would know that the true SPF or Real Life SPF in sunlight can only be 12-15 maximum. Each filter based on its UVB/UVA2 absorption efficiency has a finite SPF units per 1% concentration. This only provides minimal UVB or sunburn protection for < 1 hour in the full sun for a very fair-skinned person. If it was dispersed poorly this could fall to around 15 minutes- hence all those sunburns seen on mother-baby blogs. At 9% a second primary and safe UVB filter would be required –either titanium dioxide or encapsulated octinoxate in a concentration of 7.5% to attain a true SPF of around 25-28. Zinc oxide at >15 % with 7.5% of either titanium dioxide or encapsulated octinoxate will reach SPF 30 plus and have adequate UVA protection. 

Chart with Theoretical Maximum SPF Units per 1% of Active

Filter	Max. # of SPF Units per 1% of Active
UVB
Octinoxate	2.8
Homosalate	1.5
Titanium Dioxide	2.6
Octisalate	1.6
Oxybenzone	2.3
Octocrylene	2.1
UVA
Avobenzone	1.9
Zinc Oxide	1.6
Tinosorb M	2.2
Tinosorb S	3.1

Simply Zinc™ (CyberDERM) with 22% gives the best balanced protection and Every Morning Sun Whip ™ is not far behind. We believe both are the most esthetic zinc oxide sunscreens found anywhere. Consumers love the products knowing they are safe even for pregnancy and give maximal protection. My dermatologist wife needed a sunscreen to actually prevent skin cancer and photoaging, and as a high risk obstetrician, I needed to know filters did not pass into maternal blood and reach the fetus. A safe, effective, and esthetic sunscreen was hard to find, so we made our own.

Finally, at the World Congress in Dermatology, we learned that there may be evidence that the soluble filters are also photocarcinogenic and induce skin cancer in susceptible subjects- another reason for soluble filters to be banned under The Precautionary Principle. Imagine how egregious it is that a product could cause the disease it is supposed to prevent.  However, I am not optimistic that anything will change. Finally, several of the soluble filters – octinoxate, avobenzone and octocrylene can be encapsulated that converts them to larger size, so they behave like insoluble particles and become safe. We use encapsulated octinoxate in one sunscreen. The silica capsule is inert and the molecule now sits on the skin like zinc oxide and attains the same safety profile. Encapsulation increases the size from 0.5 nm to 7 microns- larger by about 14,000 times. Industry inexplicably ignores this technology that would make some of the offending filters safe.       

                                                                            

© Denis K. Dudley MD 2015. All Rights reserved.