Problems With Plastics: Short version

Article published in the AHVMA JOURNAL, Vol. 57, Winter 2019. P 19-21 From Mineral Oil and Multiple Sclerosis to Plastics, Nanoparticles, Public, Animal, and Environmental Health Michael W. Fox, BVetMed, PhD, DSc, MRCVS Author contact: Email Website

Abbreviations MS Multiple sclerosis PAH Polycyclic aromatic hydrocarbon

USP Grade mineral oil and petroleum jelly are byproducts of refining crude oil and petroleum. Sold in pharmacies across the U.S., they are used in lotions, sunscreen, cosmetics, and ointments, liberally applied to babies as well as the entire body after showering in the belief that this is good for the human skin. From a chemical point of view, mineral oil and petroleum jelly are “purified” mixtures of long-chain saturated hydrocarbons (also known as alkanes or paraffin) existing as solids and liquids of the general formula (CnH2n+2). These polycyclic aromatic hydrocarbons (PAHs) are of growing public health concern (1).

Lipophilic and hydrophobic petrochemicals in mineral oil may damage the insulating fatty myelin sheath over the nerves, a process called demyelinization (2). Consideration of bioaccumulation as the human body absorbs these hydrocarbons and fat solvents is paramount.

Many PAHs have toxic, neurologic mutagenic, and/or carcinogenic properties (3). PAHs are highly lipid soluble and thus readily absorbed from the gastrointestinal tract of mammals. They are rapidly distributed in a wide variety of tissues with a marked tendency for localization in body fat. Metabolism of PAHs occurs via the cytochrome P450-mediated mixed function oxidase system, with oxidation or hydrolysis as the first step. The oxidative impact on cells may cause a pathological opening of the permeability transition pore and cause mitochondrial dysfunction which may lead to multiple sclerosis (MS) that may not be simply an autoimmune disease (4).

Testing should be done to explore the plausible hypothesis that there will be a significant decline in the incidence and severity of MS and other neurodegenerative diseases when governments limit the consumer use of mineral oil and advise strongly against frequent cutaneous application. Like some other demyelinating neuropathies, multiple sclerosis is a multifactorial, pluricausal disease for which there is no solution beyond applying the precautionary principle of best prevention first. Public health and consumer and environmental protection go hand in hand but are too often divided by vested interests and conflicting values and opinions.

Environmental Health Concerns Petrochemical products from a host of items ranging from plastic water bottles, grocery bags, and styrofoam cups and packing materials to disposable pens and lighters are pervasive and a top environmental and public health issue (5-7). Polystyrene plastic cups break down into small particles that become a magnet for toxic chemicals such as polycyclic aromatic hydrocarbons in polluted sea and fresh water. As plastic debris floats in the seawater, it absorbs dangerous pollutants like polychlorinated biphenyls, dichlorodiphenyltrichloroethane or DDT, and PAHs. These chemicals are highly toxic and have a wide range of chronic effects, including endocrine disruption and cancer-causing mutations. Plastic microparticles, present in many drinking water sources and sea foods, can pass though the gut wall, possibly crossing the blood-brain barrier (8).

Plastics in Pet Foods Large pieces of plastic in manufactured pet foods occur on occasion and have resulted in nationwide pet food recalls. Microparticles of plastic may be in many pet foods because the plastic wrappings and packaging around discarded meat and poultry products, no longer fresh enough for human consumption, are recycled, rendered, and subsequently included in pet foods, in addition to livestock and poultry feed. Plastics have even been fed to cattle as a substitute for fiber, ostensibly to improve digestion. As with human foods and beverages in plastic containers, leaching from the plastic pet food bags and liners calls for immediate pet food industry attention (9).

Plastics may be applied directly onto pet foods as a preservative to increase shelf-life. Hill’s Pet Nutrition has received a patent on various coatings for dry kibble, treats, and other pet foods and supplements, some of which include petrochemicals such as polyethylene and methacrylate (10). Using such chemicals in manufactured pet foods could have unforeseen adverse health consequences as has been documented with earlier food-chemistry-based dietary formulations for dogs and cats (11).

Plastics Contribute to Climate Change The plastics manufacturing industry is becoming the biggest user of fossil fuels, and some 100 million metric tons now pollute the oceans (12). Without curtailing such pollution and with rising demand for plastics, life on Earth will be compromised, since over half of atmospheric oxygen is generated by marine plankton currently at risk from these and other petrochemicals in their environment (13).

These founders of the aquatic food chain along with coral reefs are also at risk from sea water acidification due to high levels of carbon dioxide produced mainly from the burning of fossil fuels. Forest fires associated with habitat and climate change add to the problem of rising carbon dioxide and lower oxygen levels. Phytoplankton are decimated by agrichemical-runoff, in particular herbicides, but also by microplastics (14).

Low oxygen levels in major cities have recently been reported. This may be due in part to the decline in oxygen producing and carbon fixing phytoplankton. Climate change, one aspect of a looming global eco-crisis, includes changes in atmospheric gases that support life and shield from harmful solar rays (15). Marine mammals and other ocean-dependent wildlife are washing up on our shores with signs of extreme malnourishment as well as toxic pollution. Their condition, along with weakened immune systems and reduced fertility, may be primarily due to microplastics contaminating and killing off zooplankton, the foundation of their food chain (16).

Collectively, in my opinion, plastics and other petrochemical products represent one of the most harmful contributions of the chemical industry to health and life because the issues of containment and safe disposal have never been considered. The atmospheric transport and terrestrial deposition of plastic microparticles are now documented (17, 18). Such consideration is most urgent for the planet’s detoxification and our recovery from the Industrial Age of Chemistry with its adverse impacts on environmental and public health, the judicious use of insecticides and antimicrobials notwithstanding. The growing recognition of such anthropogenic factors in the genesis of “diseases of civilization” and ecological and physiological dysbiosis has spawned the One Health concept and movement in medical and veterinary practice, teaching, and research (19). We must quickly create and expand alternative products based on eco-friendly biochemical processes such as contained bio-fermentation and biosynthesis, bioremediation, sustainable biofuels, and other alternative energy sources. Consideration should be given to natural clothing and other materials derived from sources like cotton and hemp that are recyclable and biodegrade into non-toxic components. Efforts local and international to recover plastic materials from all contaminated aquatic ecosystems and unsealed land-fills need to be initiated for the common good. Disposing of plastics by burning/incineration should be avoided since highly toxic dioxins will then be released into the environment.

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