How common chemicals affect the environment and your body
As you go about your everyday life, you are exposed to a large and increasing number of chemicals. Although many people follow common sense and try to avoid unnecessary chemical exposure, some others like to shrug off warnings and put on a show of bravado as a means of reinforcing a tough self-image. Such an attitude is encouraged by the chemical industry itself, which helps to spread the term “chemophobia” in an attempt to make a precautionary approach to these risks look irrational.
Despite there being more than 80,000 chemicals in common use worldwide, most are yet to be tested for their toxicity, and large knowledge gaps remain. Among those known to cause health effects, we frequently encounter benzene from unleaded petrol at service stations, bisphenol A (BPA) on some shopping receipts, phthalates wafting at us from perfumes, and flame retardants in household dust.
Together with the outer environment, your body is being polluted, too. The average person living in a technologically advanced country has measurable levels of several hundred different chemicals in his or her bloodstream. Among US residents, 93 per cent tested positive for BPA, 97 per cent possessed levels of the flame-retardant penta-PBDE, and 100 per cent had at least one pesticide.
Modern toxicology is strongly influenced by the 16th century physician Paracelsus whose words have been distilled into the phrase “The dose makes the poison” to imply that toxic chemicals in very low concentrations are harmless. Over the intervening centuries, however, science has evolved and developed far greater sophistication. More recent findings include:
- The need for a zero safe limit for highly toxic substances, such as mercury and lead, that are persistent (resistant to biodegrading in the environment) and bioaccumulative within the body when they are absorbed faster than they can be removed by the natural detoxification pathways.
- The endocrine-disrupting effects of xeno-oestrogens (chemicals that mimic estrogen in the body) such as atrazine, phthalates and BPA, which are most potent at lower concentrations.
- Cases where there is a synergistic interaction between low doses of two or more chemicals to produce disproportionately greater effects than would be expected individually.
Pesticide exposure limits
Pesticides are widely found in non-organic foods and their levels are regulated in many countries under a system of Maximum Residue Limits (MRLs.) In Australia, this is administered by the Australian Pesticides and Veterinary Medicines Authority (APVMA), a body that receives all of its funding from industry via a “cost recovery” model.
The APVMA website indicates that MRLs are set by establishing levels not likely to be exceeded in the course of normal application of the chemical. The second stated consideration is to ensure that they do not pose an “undue hazard” to human health, seeming to imply that a slight hazard is acceptable. In New Zealand, these limits are set by the Ministry for Primary Industries.
Unfortunately MRLs by themselves do not guarantee that your health will be protected, and the notion that a substance suddenly becomes safe below a specific level is simple-minded. This is reinforced by some remarkable MRL discrepancies across jurisdictions. For the use of the organochlorine dicofol on strawberries, Australia’s MRL is 1mg/kg, New Zealand applies 3mg/kg and in the US the limit is 10mg/kg. In the EU, where it is banned, a figure of 0.02mg/kg has been set.
Behaviour in your body
Following intake into your body, some chemicals such as arsenic and phthalates are quickly excreted. Others accumulate in human tissue, including the brain, kidneys, liver and breasts. Rates of excretion vary considerably, with lead being the slowest.
This build-up of chemicals is known as the “body burden” and is being passed down the generations. Tests by the Environmental Working Group in the US looked at the umbilical cord blood from 10 infants born in US hospitals and detected, on average, 287 different chemicals.
Young children are at particular risk. They crawl on the floor and put their hands and a range of objects into their mouths. Compared with adults, they take in greater levels of environmental toxins proportional to their bodyweight.
As adults mature, the usual scenario is for the body burden of bioaccumulative substances to steadily increase. In Australia and New Zealand, about 1 per cent of the population has been medically diagnosed with multiple chemical sensitivity, often experiencing headache, fatigue, confusion and depression. A far greater chunk of society encounters similar symptoms to some degree but has not yet been diagnosed.
Growing numbers of health-affected people are searching for ways to remove these toxins. One option involves the use of chelating agents such as EDTA (ethylenediaminetetraacetic acid), DMSA (dimercaptosuccinic acid) and DMPS (dimercapto-1-propane-sulphonic acid), which bind with heavy metals and remove them from the body. The safety and effectiveness of these agents are questioned by the medical mainstream, except as treatments for lead poisoning.
Among the criticisms levelled against chelation are the stripping of essential minerals from the body and the fact that excretion occurs via the kidneys, a riskier avenue than through the gastro-intestinal tract. Natural and harmless chelators include garlic, fresh coriander, chlorella and amino acids, which are synthesised from proteins.
Two other natural chemical detoxification avenues are taking a milk thistle supplement and having saunas.
Traditionally, it was believed that toxic exposures could always be evaluated through a dose addition model. Unfortunately, this reductionist approach is overly simplistic and out of step with the highly complex interactions that are likely to occur, especially when multiple chemicals interact.
Scientific attention is increasingly being turned towards synergistic effects, where certain chemical combinations have been observed to have a toxic impact in excess of that expected from the component chemicals, sometimes to a remarkable degree. Very similar is potentiation, where the effects of one toxic chemical are increased by another with no particular toxicity.
For pesticides, the setting of MRLs is influenced by what is known as the “no observed effect level” (NOEL), a daily intake of individual toxic substances at which no statistically significant effects are observed when compared to a control group. Unfortunately, the existence of these synergies undermines the validity of the NOEL model. There is an increasing body of opinion that synergistic chemical interactions may be responsible for the steep increase in the incidence of asthma and autism, and for growing numbers of cancer and diabetes (see Special Report this issue) diagnoses per head of population.
Synergy in the real world
Chemicals are commonly found in our food, air, pharmaceuticals, vaccines, personal care products and workplaces, giving scope for a vast number of synergistic interactions. Among the best-known …
- One meal may contain traces of numerous different pesticides, including the synergists piperonyl butoxide and pyrethrins which together result in a heightened insecticidal activity.
- About 90 per cent of Australians receive fluoridated water. In addition to its neurotoxicity, fluoride combines synergistically with another neurotoxin, aluminium (sources include drinking water, some processed foods, aluminium cans, aluminium foil, aluminium pans, some vaccines, antiperspirants, industry), to form aluminium fluoride. The presence of fluoride enhances the bioavailability of aluminium, causing more to be deposited in the brain, where it is suspected of being a major cause of Alzheimer’s disease.
- Mercury (from fish, coal-fired power stations, amalgam fillings, some vaccines and some high-fructose corn syrup) has powerful synergistic effects in combination with lead (pre-1970 paint chips, household dust in houses with old paint, industry). Similar effects occur when mercury combines with aluminium.
- The latest autism figures from the US show that the condition affects one in 88 children, with a remarkable gender bias towards males (one in 54 boys compared with one in 252 girls). The primary explanation for this could lie with mercury; testosterone and mercury combined are synergists, whereas estrogen inhibits the effects of mercury.
- Thiomersal is a preservative that is about 50 per cent mercury by weight. Controversially, it came to be used in very low concentrations in vaccines, from which it is now steadily being removed. In Australia, three vaccines still use thimerosal (for hepatitis B, Fluad for flu, and Fluarix for flu). No vaccines used in New Zealand contain this substance.
- Haley and Lovell have found that when three vaccine ingredients were combined (thimerosal, aluminium hydroxide and neomycin) it resulted in a synergistic toxic effect that was further concentrated by testosterone.
- The antibiotics ampicillin and tetracycline, along with acetaminophen (paracetamol), also have synergistic interactions with thimerosal.
- Tungsten, nickel and cobalt are metals that have a collective toxic synergy. In terms of everyday exposure, tungsten wedding rings are commonly alloyed with either nickel or cobalt as a binding agent.
- Researchers have been investigating Gulf War Syndrome, a condition associated with the first war in Iraq, involving a range of symptoms including fatigue and nervous system damage. Recent research suggests the cause may have been a mix of the topically applied insecticides DEET and permethrin coupled with the nerve gas protection drug, pyridostigmine bromide.
- Carbon tetrachloride is an ozone-depleting greenhouse gas whose production has steeply declined in recent decades. Today, it is limited to a very narrow range of “essential uses”. When combined with ethanol (alcoholic drinks) or isopropanol (rubbing alcohol), a far greater liver toxicity was observed.
- The two industrial substances melamine and cyanuric acid are toxic to the kidneys when combined. This was identified following a 2007 pet food scandal in which American cats and dogs died after eating pet foods made with Chinese-origin wheat gluten and rice protein contaminated with both chemicals.
- Cigarette smoke, radon (a natural indoor radioactive pollutant that hardly occurs in Australia and New Zealand) and asbestos result in a significantly greater risk of lung cancer when combined than when individual exposures occur.
- It has been observed from tests on carp that titanium dioxide nanoparticles (some sunscreens, cosmetics, paints, vitamin supplements and sweets) increase the take-up of the toxic heavy metal, cadmium (smoking, industrial, some non-organic foods).
- Sometimes, the cervical cancer vaccine Gardasil is given together with the meningococcal disease vaccine Menactra, with figures from the US Vaccine Adverse Event Reporting System indicating a 1130 per cent increase in incidences of Guillain-Barre Syndrome (an autoimmune condition that can lead to muscle weakness and spreading paralysis) compared to occasions when Gardasil was given alone. Where the vaccines were combined, the incidence of injuries from falls following unconsciousness increased by 674 per cent.
- Tests in 2002 by a team led by toxicologist Dr Nissanka Rajapakse involved adding 11 weak xeno-oestrogens to the natural oestrogen 17ß-estradiol, all below their NOELs, and found that the oestrogenic power of 17ß-estradiol was doubled.
Minimising exposure is the key
Despite the limited quantity of research in this field, synergy looks set to remain part of the toxicology landscape. Instead of getting too bogged down in complexity, the best solution for people trying to follow a holistic lifestyle is to keep exposures to a minimum and to be aware that some chemicals are found in surprising places. Inevitably, we are being exposed to a greater range of toxins than we are aware of, as a certain level of invisible chemical exposure goes hand in hand with living in a technologically advanced society.
However, this doesn’t mean we should give up; while reducing exposure levels down to zero is probably unrealistic, having a blood concentration that is several times smaller than average puts us in a safer position. Following the precautionary principle is sensible, and perhaps the single most important step is to eat an organic diet.
Another important avenue is to become activist and challenge companies, calling for a shift towards cleaner production. Regulation is another vital dimension; when even the mainstream media gives us lists of everyday products to avoid, it begs the question why are they still being made?
A more extreme solution is to drop out of modern society, at least to some degree. While living in a cave is fairly impractical, groups choosing a low-technology lifestyle, such as the Mennonites and Amish in the US, have been found to have a remarkably lower body burden than American society as a whole.
Martin Oliver is a writer and researcher based in Lismore, Northern NSW, Australia.