Whether it is about foodstuffs, body care products, cleaning agents or other everyday items, we are constantly exposed to various additives, emulsifiers, flavor enhancers, preserving agents, colorants, chemicals and many other harmful substances. Depending on their relevant substance class and quantity, these compounds may present a health hazard, can be irritant, poisonous and/or have a negative impact on our reproductive health.
Regional or global trend?
For more than 30 years now it has been debated whether or not human fertility (in particular male fertility) is on the decline and, if yes, why? Studies on these topics have led to partially contradictory results, some of which imply that fertility is expected to decline on a global scale, while others see the changes only at regional level.
Surplus of women due to pollutants?
The gender ratio of newborns belonging to certain ethnic groups gives rise to questions. For example, nowadays, we are witnessing a substantial shift in gender ratio towards females among the Inuit living in the Arctic. According to media reports and relevant literature, the bodies of Inuit have been found to contain extremely elevated concentrations of toxic chemicals. Probably the reduced degradation of harmful substances, which, in turn, is due to the low temperatures and their associated accumulation in the fatty tissue of humans and animals (bio-accumulation) is the reason for the gender imbalance. However, this is still an unverified assumption.
Large scale disasters
In July 1976, some 20 kilometers north of Milan: The industrial accident which led to the release of unknown amounts of the most toxic form of dioxin (TCDD) went down to history as Seveso disaster.
Is it pure coincidence that within eight years after the accident, the gender ratio of newborn babies of especially burdened parents was 48 girls compared to just 26 boys and that only baby girls were born to nine couples who were exposed to the highest dioxin concentrations? It is hard to tell on the basis of such limited case numbers.
Numerous studies have linked environmental pollution to poor sperm morphology and motility, such as the detailed survey from the contaminated area of Teplice in the Czech Republic carried out in the mid-1990s. A growing body of research demonstrates a correlation between extremely poor sperm quality and a high biocide load. Have all these studies come to the wrong conclusions?
Dangers of everyday life
In our times, we are as never before, constantly exposed to a large number of different chemicals – in all areas of daily life. It makes one wonder that, on the one hand, we scrutinize issues such as IVF techniques, but that, on the other hand, we just simply accept to be exposed to harmful substances in everyday life. There now follows a basic overview of the substances and areas of life which we do not or hardly ever challenge with regard to their possible impact on health and reproduction:
- Sleep: Polyurethane foam mattresses
- Body care: Shower gels, shaving foams, deodorants etc. contain, among other ingredients, diethanolamine (DEA), diethyl phthalate and oxybenzone.
- Clothing: Contaminated with residues of azo dyes, chlorine compounds etc.
- Food: Eating convenience foods, we consume vast amounts of additives, colorants, flavor enhancers or preservatives.
- Stimulants: In addition to nicotine and aromatic amines, tobacco smoke contains benzene, PAHs (Polycyclic Aromatic Hydrocarbons), formaldehyde and many other compounds. The coffee cup is made of polycarbonate plastic, the coffee machine’s window showing fill level contains bisphenol A (BPA) , which is an endocrine disruptor that is suspected of having a negative impact on the sexual libido and semen quality and may irreversibly impair the maturation of the brain of unborn infants.
- Hypochlorite, percarbonates and perchlorates are ingredients of cleaning agents.
- Sales slips, parking tickets or other tickets produced of thermal papers are contaminated with BPA.
- The air in the passenger compartment of a new car contains formaldehyde, benzene and more than 50 volatile organic compounds.
- Particulate matter, compounds evaporating from your office chair, toner particles from the printer (artificial resins, various metal oxides) and so on
Humans and animals
It is estimated that some 350 tons of plastic waste end up in the sea– nota bene: per hour. The marine ecologist Richard Thompson (Plymouth University) has investigated sand samples from the beach of Plymouth. His findings revealed that the sand contains about 5 – 10% of tiny plastic particles. You can be assured that a large share of plastic waste ends up on our plate!
Researchers from the University of Lund added polystyrene nanoparticles to an algae culture which was subsequently used to feed zooplankton. After a while, the zooplankton was used as feed for crucian carps (species of the carp family). The corresponding paper published in the scientific journal PlosOne reports on changes in behavior and fat metabolism of these carps.
Research findings from the animal kingdom cannot, of course, simply be extrapolated to humans. But who can actually believe that substances having an impact on the behavior of fish and the fertility of mice, compounds that impair the quality of their embryos and have a negative effect on the oogenesis in rhesus monkeys would not affect human health and reproductive capacity in the long run!
Oxidative stress
Endocrine disruptors (also called xenohormones) act similarly to endogenous hormones (such as BPA), which means they interfere with the endocrine system. Others such as oxygen compounds referred to as ROS (Reactive Oxygen Species) act as highly reactive substances and may severely damage cell components. If the body’s own antioxidants do not render these ROS harmless and repair cell damages, this situation is referred to as oxidative stress. Ova and spermatozoa, in particular, are affected. The repair mechanisms of sperm do not respond properly to the attack since they are transcriptionally inactive. Owing to their cell membrane that contains an especially large number of polyunsaturated fatty acids, spermatozoa is particularly sensitive to ROS damage.
Tangible scope for improvement
At our IVF Centers Prof. Zech, in many cases, we could observe an improvement in semen analysis through the administration of an anti-oxidative preparation over a period of several months, both in terms of sperm morphology (according to the MSOME criteria that we employ) and concentration as well as in terms of sperm motility.
Long-term effects
Environmental toxins and other factors directly interfere with gametes (reproductive cells) and embryos. In addition to cytotoxic and mutagenic properties (potential to directly reduce a cell’s vitality or damage genetic material), certain substances may trigger epigenetic alterations. The genome (genetic makeup) remains unaltered, but genomic imprinting will be modified.
Thus, your behavior does not only have an impact on your own health, but also affects the health of your children, grandchildren and so on. Keep this in mind, before smoking your next cigarette while waiting in front of the microwave for your convenience meal.
Please refer to one of our next blog entries to learn more about epigenetic influences interacting with environmental and lifestyle factors.
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