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By Douglas Ebersole, MD
Header photo by Becky Kagan Schott, Selfie with Jitka Hanakova.
Historically, technical diving has been a male-dominated sport; however, that is changing. In fact, at this year’s Bonaire Tek event in October, there were 24 women in attendance, representing almost 30% of the attendees. Little attention has been paid to issues unique to women in technical diving. This article will address a number of these. Specifically, it will discuss the risk of decompression illness (DCI) in women versus men, changes in risk of DCI at various times during the menstrual cycle as well as the effects of oral contraceptives, pregnancy, cosmetic and reconstructive surgery, menopause, and cardiovascular health.
In an attempt to show full transparency, I am NOT a woman, and I fully understand that immediately puts my credibility into question. However, I have lots of family and friends who are women technical divers, and I reached out to them for help deciding on topics to approach. Thanks to my wife, who is a rebreather diver; our daughter, who is a rebreather instructor; Jill Heinreth, Becky Schott, Mel Clark, Jo Mikutowicz, and Rosemary “Roz” Lunn for their input. I also heavily referenced a textbook by Caroline Fife, M.D. entitled Women Under Pressure.
Decompression Illness and Gender
When looking at women and the risk of decompression illness, three factors bear consideration. First, do women and men differ in their risk for decompression sickness when under the same decompression stress? Second, what (if any) effect does a woman’s menstrual cycle have on her risk for decompression sickness? And, finally, what is the data on decompression sickness risk while on oral contraceptives?
The data we have on DCI risk based on gender is retrospective and inconclusive. In a paper in Undersea Biomedical Research in 1987, Zwingelberg looked retrospectively at Navy divers, 28 women and 487 men, with a combined 878 training dives with equal representations of exposures. In this study there was no difference in risk of DCI by gender.
In 1992, in Undersea Biomedical Research, Robertson retrospectively looked at 111 cases of DCI in Australia. In this report, women had a 4.3 times greater incidence in Type II decompression sickness compared to men.
In 1993, Vann reported on this issue using the Divers Alert Network (DAN) flying after diving data and published in Aviation Space and Environmental Medicine. His data also suggested that women had a higher risk of Type II decompression illness compared to men and had more residual symptoms. However, he mentioned that it was unclear if the incidence was truly higher or if there was reporting bias.
In another study in Aviation Space and Environmental Medicine in 2002, St. Leger Dowse sent questionnaires to divers (53% men and 47% women). This data suggested that before controlling for diving patterns, women had a 1.67 time greater risk of DCI. However, after controlling for diving patterns, men actually had a 2.57 time greater risk of DCI.
Finally, Hagberg reported in Undersea and Hyperbaric Medicine in 2003 on 1,516 male and 226 female diving instructors and dive masters who self-reported their incidence of DCI. This data set contained thousands of dives of various types and showed a risk of DCI for men of 1.52 per 1,000 dives and a risk of DCI for women of 1.27 per 1,000 dives.
In conclusion, the differences in dive profiles in the available observational data make it impossible to draw firm conclusions regarding the effect of gender on DCI among scuba divers.
Decompression Illness and the Menstrual Cycle
A woman’s menstrual cycle is typically 28 days and is controlled by the interactions and levels among three hormones: estrogen, progesterone, and testosterone. Several retrospective studies have tried to correlate the risk of decompression illness at various times during the menstrual cycle. In 1998, Lee et al, reviewed 73 records and found 35% of DCI events occurred within the first five days of the menstrual cycle.
In 2006, St. Leger Dowse reviewed more than 50,000 dives and 11,000 menstrual cycles in 570 women. This showed the highest incidence of diving problems was in the first week of a 28-day cycle while the lowest risk was in week three. She then also reported in 2006 the results of 250 prospective DCI records and found the highest incidence of DCI was in the first week while the lowest incidence was in the third week of a 28-day cycle.
While the data above for menstruating women suggests a higher risk of DCI in the first week of their cycle, the data for women on birth control pills is less clear. These women have a pharmaceutically driven menstrual cycle. While studies have assumed a 28-day cycle in these women, St. Leger Dowse in the Journal of Obstetrics and Gynecology in 2007 reported that only 42% of women on oral birth control pills had a 28-day cycle. The remainder ranged from 21 to 60 days. As a result, the data on DCI in women on birth control pills is clouded, inconclusive, and confusing.
In conclusion, the mechanism of risk across the menstrual cycle is not known, but hormonal fluctuations may be a possible factor. And one final note – while menstruation may decrease exercise tolerance due to anemia and volume depletion, it does NOT increase the likelihood of shark attack.
Pregnancy and Diving
Human data on the effects of hyperbaric oxygen on the fetus are limited. In 1980, Bolton reported in Biomedical Research on 109 women who dived before and during pregnancy compared to 69 women who dived before pregnancy but stopped diving once pregnancy was diagnosed. Babies born to women who dived during pregnancy had lower birth weights, more respiratory difficulty, and birth defects, including hemivertebrae, absence of a hand, a ventricular septal defect, coarctation of the aorta, and pyloric stenosis. It should be noted that there were no birth defects in the babies born to women who stopped diving when they learned they were pregnant.
Once again, St. Leger Dowse chimed in on this issue. She reported in Obstetrics and Gynecology in 2006 on retrospective data from 1990-1992 and prospective data from 1996-2000 on 129 women who continued to dive, either purposely or inadvertently, during their pregnancy. This involved 1,465 dives during 157 pregnancies. Of note, while only 65% of women stopped diving during the first trimester of their pregnancy in 1990-1992, by 1996-2000 this number increased to 90%. For the total population, the incidence of spontaneous abortion was 14% and the serious birth defect rate was 2.7%, which is similar to the rate in nondivers.
Of course, if DCI occurs in a pregnant woman, the fetus also becomes a patient. Because of fetal blood flow, venous bubbles in the mother will be arterialized into the systemic circulation of the fetus through the foramen ovale, which could be devastating. Of note, there is no data on fetal injury related to maternal hyperbaric therapy.
There are other issues with diving during pregnancy not related to decompression stress. Pregnancy increases total body water and swelling of mucous membranes, making equalization difficult. Two-thirds of women have nausea and vomiting, or “morning sickness,” in early pregnancy. Additionally, gastric reflux (heartburn) is very common during pregnancy and is already common with immersion for any diver.
After vaginal delivery, women should refrain from diving for 21 days postpartum to allow time for the cervix to close so as to lessen the risk of ascending infection. After cesarean delivery, most obstetricians recommend refraining from diving for 4-6 weeks.
The issue for diving during breastfeeding is the risk of marine bacteria colonizing on the skin, resulting in mastitis in the mother and bacterial diarrhea in the infant.
Diving and Breast Augmentation
In the early 1980s, Divers Alert Network began receiving calls about the concern of dissolved gas expanding on a commercial flight home putting stress on the seams of breast implants. In 1988, Vann reported in Plastic and Reconstructive Surgery on the results of hyperbaric followed by hypobaric conditions on a variety of saline and silicone implants. Depths were as deep as 120 ft/37 m and dives times of up to 72 hours. Then, after a 21-hour surface interval, the implants were taken to 7000 ft/2.1 km for two hours and then to 30,000 ft/9.1 km for two hours to simulate loss of cabin pressure. The implant volume increased 1.0-4.0% at the surface, 0.0-5.0% at 7000 ft/2.1 km, and 4.0-12.0% at 30,000 ft/9.1 km. Saline implants were less affected than silicone implants, all bubbles resolved over time, and the volume change was not enough to risk rupture.
Post operatively after breast augmentation, women should wait 4-6 weeks before returning to diving and avoid putting tight shoulder straps over the implants to avoid undue pressure. Finally, while saline implants are neutrally buoyant, silicone implants are negatively buoyant.
Diving, Smoking, and Oral Contraception
Fourteen percent of women age 14-44 use oral contraceptives. These birth control pills have been shown to increase the risk for forming blood clots resulting in stroke, heart attack, deep venous thrombosis (blood clots in the legs), and pulmonary emboli (blood clots in the lungs) in women who smoke. While nonsmoking women on birth control pills who are less than 35 years of age have no increase in risk compared to nonsmoking women not on birth control pills, women who smoke have a significant increase in the risk for these conditions.
Compared to nonsmokers who are not on birth control pills, women who smoke less than one pack per day while on birth control pills have a three-fold increased risk of these conditions, while smokers of more than one pack per day have a 23-fold increased risk.
Diving and Menopause
Twenty-two percent of women divers making more than eight dives per year are 55 years of age or older. During menopause, women are at a much higher risk for osteoporosis than men due to a baseline lower bone density, followed by the loss of estrogen which accelerates the rate of bone demineralization. The average age for menopause is 50 years, and bone loss increases dramatically after this. Significant bone loss will be seen at 60-70 years and fractures begin occurring at 70-75 years. Thankfully, there are now treatments to blunt this bone loss. Women with significant osteoporosis of the spine should be cautious about walking while wearing scuba cylinders due to an increased risk of vertebral crush fractures.
Cardiovascular Disease and Menopause
The leading cause of death in women is cardiovascular disease. In addition, approximately 100 U.S. and Canadian divers, both women and men, die while scuba diving each year. Twenty-five percent of those over age 35 have a cardiac cause. While the risk for cardiovascular death is quite low in premenopausal women, after menopause, the risk for women quickly becomes comparable to that of men. As a result, all women, like their male counterparts, should be vigilant in controlling the risk factors for cardiovascular disease, emphasizing blood pressure and cholesterol control, screening for and treating diabetes, and avoiding smoking in addition to exercise and weight control.
- Women are at increased risk for decompression illness during the first week of their menses.
- The risk of decompression illness for a woman on oral contraceptives is unclear.
- A woman diver should stop diving as soon as she knows or suspects that she is pregnant.
- Breast implants can swell when going from hyperbaric (diving) to hypobaric (air travel) environments, but not enough to risk rupture.
- Women, especially those on oral contraceptives, are at a much greater health risk if they smoke.
- Osteoporosis with aging can put women at risk for spinal compression fractures.
- Cardiovascular health is as important a concern for women as it is for men.
Douglas Ebersole, MD, is an interventional cardiologist at Watson Clinic in Lakeland, Florida, and the Director of the Structural Heart Program at Lakeland Regional Health. He is also an avid technical diver, cave diver, and CCR trimix instructor, as well as cardiology consultant to Divers Alert Network (DAN).
Preserving Florida’s Springs: The Bottled Spring Water Problem
There’s no doubt that Florida’s Springs are imperiled. Most are flowing 30% to 50% less now than their historical average and are suffering from eutrophication. However, as veteran hydrologist Todd Kincaid explains, the problem is not spring water bottlers like Nestlé, in fact they could be allies in the fight to preserve the springs.
By Dr. Todd Kincaid
Header photo by Florida DEP of Wakulla Springs in April 2008.
Florida’s Springs are imperiled. Most are flowing 30% to 50% less now than their historical average. Some don’t flow at all except after big storms or abnormally wet periods. Nearly all have become overwhelmed with algae and bacteria (eutrophied) due to excessive nutrient pollution. The causes are straightforward and increasingly hard to ignore: groundwater over pumping, the overuse of fertilizers by agribusiness and homeowners, and insufficiently treated wastewater. Solutions exist, can be widely implemented, and would significantly improve spring water flows and spring water quality, but they require major investments and diversions from status quo: caps on groundwater extractions, tiered fees for groundwater usage applied to all users, tiered taxation on fertilizer usage, advanced wastewater treatment, transition away from septic systems, etc.
Existing policies have failed to even bend the steep downward trajectory of Florida’s springs. “Minimum Flows and Levels” (MFLs) appear to protect spring flows but, in reality, they open the door to continued declines while people argue over the difference between natural and human causes. “Best Management Practices” (BMPs) pretend to reduce nutrient loading, yet are not only unproven and unenforceable, but not even conceptually capable of the needed nutrient reductions. Even as more and more attention and resources are directed at the condition of Florida’s springs, most continue to degrade: less and less flow, more and more nitrate and algae.
In the face of these declines, it’s easy to become disheartened and jaded. It’s even easier to become focused on reactionary measures aimed at what we don’t want and be rooted more in emotion than in facts. This is, I believe, epitomized by the highly publicized reactions to a permit renewal application filed with the Suwannee River Water Management District (SRWMD) by the Nestlé Corporation (Nestlé) for a bottled spring water plant down the road from Ginnie Springs.
The application requests that the SRWMD renew a standing permit that was first issued in the 1980s for the extraction of 5 million gallons per day (MGD) of groundwater from the Floridan aquifer to support spring water bottling. This same permit was voluntarily reduced to 1.1 MGD by the property owners to prevent the possibility that it could be incorporated into one of the many groundwater pipeline schemes that are persistently proposed to transport water from relatively rural north Florida to the substantially more populous cities in central and south Florida. Through the years, several different companies have leased the property and had access to the water, one of which was the Coca-Cola Company, and the most recent being Nestlé.
My perspective on this issue is a product of 30 years of work on karst hydrogeology in Florida, more specifically from my work for Coca-Cola on mapping groundwater flow paths. Specifically, we mapped the pathways to the springs on the western Santa Fe River, including Ginnie Springs, and identified the threats to the quality and quantity of flow to the springs. Even more, my perspective reflects the evolution of my understanding of what it’s going to take to sustainably manage groundwater (synonymous with spring flow) in Florida.
The problems facing Florida’s springs are not technical and not a consequence of any one particular use or user. The real problems are instead failures of the established policies to take the necessary steps to put concrete limits on groundwater consumption and pollution. If we are to achieve sustainable spring flows, limits on groundwater consumption must be established and enforced and, in reality, must be lower than current levels.
From a quantity perspective, who gets the water is irrelevant. All that matters is how much is taken. At present, not only is too much being taken, but there are no established limits. Conservation measures enacted by one user simply opens the door for new or larger allocations to other users. This is accomplished when users of the water claim a “beneficial use”. So, while we can and should be proud of those engaged in conservation, the reality is that spring flows will continue to decline.
If we are to restore and preserve spring water quality, nutrient pollution, specifically the input of nitrate and phosphorous into Florida’s groundwater that stimulate the explosive algae growth in Florida’s springs, rivers, lakes, and estuaries that nobody wants, must be dramatically reduced from current levels. Some experts state that nutrient discharge levels will need to be cut across the board by 70% or more in order to meet water quality targets for Florida’s natural waters. That would mean 70% less nutrient loading from agriculture, 70% less nutrient loading from households, and 70% less nutrient loading from wastewater treatment and disposal.
At present, and for the foreseeable future, there is insufficient political will to achieve any of these needed changes given resistance from corporate and special interests. Year after year, proposed legislation calling for the types of sweeping changes needed fails to receive sufficient public support for passage. While the political efforts that would result in real and positive change continue to fail due to lack of support, the public’s attention focuses on perceived impacts from individual users without regard to the actual impacts those users and uses have on the springs.
Bottled spring water is only one example. Though the entire industry uses only around 1/100th of 1% of the groundwater extracted from the Floridan aquifer and produces absolutely none of the toxic nutrient loading that is killing the springs, it holds a disproportionate grip on the public’s attention to usage, impacts, and solutions. If tomorrow the entire bottled water industry in Florida were to shut down, there would be effectively zero improvement at the springs in terms of either flows or quality. The little amount of water gained would very likely be quickly and quietly allocated to other users.
If, on the other hand, the roughly 400 bottles of water needed to produce a single bottle of milk were put to better use, say returned to the springs, and the associated nutrient loading to groundwater due the fertilizers used to grow the feed, were thereby eliminated, there would be a near immediate improvement in both flow and quality of water at the springs. Milk production uses far more water and produces drastically more nutrient pollution than the production of water. The water saved by eliminating milk production would, therefore, take longer to re-allocate to new users and eliminate a huge portion of the nutrient pollution that is killing the springs as well.
Far more water is used for that purpose, and much more nutrient pollution is caused.
Eliminating the production of milk, for example, would also require more time to re-allocate to new users and would eliminate a substantial portion of the nutrient pollution that is killing the springs.
Nearly every drop of water extracted from the Floridan aquifer and not returned reduces spring flows by an equal amount. Certainly from the entirety of the state north of Orlando and Tampa, and regardless of what it’s used for, from water from household taps, watering lawns and golf courses, car washes, crop irrigation, production of milk, soda, energy drinks, and bottled water. Similarly, all the nutrient loading to groundwater west of central Orlando and Gainesville and south of Tallahassee flows to the springs and contributes to the explosive algae infestations, which no one wants to see become normal.
The problems plaguing Florida’s springs stem from these realities, regardless of whether the springs are enshrined as State Parks or privately owned. Florida’s springs need allies not rhetoric—allies who help to build the public support necessary to achieve the only actions that will restore and preserve spring flows and spring water quality: caps on groundwater consumption and dramatic reductions in nutrient loading.
Regardless of corporate culture, spring water bottlers’ economic self-interest is directly aligned with springs protection. Spring water cannot be treated and cannot be captured if there are no more springs. Spring water bottlers, therefore, rely on access to sustainable, high-quality spring water. It then follows that they, along with other like-minded entities, can be strong allies for springs protection. It’s time for Floridians to stop focusing on rhetoric that fails to yield even as little as a diminished rate of springs degradation. It’s time to start working toward real solutions anchored in the realities of water and nutrient budgets. The bottled water industry is not sucking Florida dry, but denial and political inaction are.
As an organization focused on sustaining the environmental quality and required to support healthy underwater ecosystems, our task must be to confront environmental problems from a perspective grounded in the realities of what will be needed to achieve our goal. We must work for what we know we want rather than against what we think we don’t want. And to be successful, we’re going to need as many allies as we can muster.
At Project Baseline, we should and will seek to engage with the people and organizations who share our goals, even if doing so is not palatable to some of our fellow conservationists. We should work with those entities and use our voices, our votes, and our wallets to foster the policies and the actions that are needed to restore and preserve the type of underwater world we want to dive in, be awed by, and pass along to the next generation of underwater explorers.
Project Baseline is a nonprofit organization that leverages their unique capacity to see how rapidly the underwater world is changing to advance restoration and protection efforts in the local environments we explore and love. Since 2009, Project Baseline has been systematically documenting changes in the underwater world to facilitate scientific studies and establish protection for these critical underwater environments.
Todd is a groundwater scientist, underwater explorer, and advocate for science-based conservation of water resources and aquatic environments. He holds BS, MS, and Ph.D. degrees in geology and hydrogeology, and is the founder of GeoHydros, a consulting firm specializing in the development of computer models that simulate groundwater flow through complex hydrogeologic environments. He has been an avid scuba diver since 1980, having explored, mapped, and documented caves, reefs, and wrecks across much of the world. Todd was instrumental in the founding of Global Underwater Explorers (GUE) in 1999 and served on its Board of Directors and as its Associate Director from its inception to 2018. Within the scientific and diving communities, Todd advanced the use of volunteer technical divers and the data they can collect in endeavors aimed at understanding, restoring, and protecting underwater environments and water resources. He started Project Baseline with GUE in 2009 and has been the organization’s Executive Director from its beginning. More on Todd at: LinkedIn and ResearchGate
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