Supporting Information

Eissen M, Backhaus D (2011) Pharmaceuticals in the environment: an educational perspective. Environ Sci Pollut Res. DOI: 10.1007/s11356-011-0512-6

Worksheets concerning the topic “Pharmaceuticals in the environment”

Title

Pharmaceuticals in the environment: an educational perspective

Author names

Marco Eissen, Donata Backhaus

Author affiliations

Gymnasium Ganderkesee, Am Steinacker 12, 27777 Ganderkesee, Germany

Name and address of corresponding author

Marco Eissen, Gymnasium Ganderkesee, Am Steinacker 12, 27777 Ganderkesee, Germany

Phone +49 4222 920197, Fax +49 04222 808868,

Journal name

Environmental Science and Pollution Research

1 Chemicals in the environment

A variety of different synthetic chemicals are found all over the world because they are widely used, do not easily "break down" and are carried to other places by air, water and via bio-accumulation through the food-chain. The different chemicals or sometimes their more harmful breakdown products, are found in soil, water, plants and animals everywhere from the South Pole to the North Pole. All animals, including humans, accumulate some of these chemicals in their fat tissue and often pass them on to their offspring and predators. In some cases where wildlife and humans are accidentally exposed to chemicals it causes reproductive and developmental problems - for instance:

Alligators living in the Florida Lake Apopka were exposed to the […]estrogenic pollutants dicofol, DDT and its metabolites, DDD, DDE and chloro-DDT, when a nearby chemical plant had an extensive spill in 1980. Ten years later, researchers trying to find out why the alligator population was dropping in the Lake, found higher than normal mortality among eggs and new-born alligators. They also found that adolescent females had severe ovarian abnormalities and had blood oestrogen levels two times higher than normal. The male juvenile alligators were feminised, that is, they had smaller than normal penises, had abnormal testes and had higher oestrogen levels and lower testosterone levels in their blood than normal males of the same age. The researchers concluded that chemicals from the spill not only killed developing eggs outright but also altered the embryo’s endocrine system (hormone level and sexual development), which severely limited the alligators ability to reproduce.

Scientists from the “Norsk Polarinstitut” have, in conjunction with Canadian scientists, just completed a comprehensive investigation into polar bears. The scientists documented that a high exposure to PCB has a negative impact on sex hormones, metabolism hormones and stress hormones and that the relatively high occurrence of pseudo-hermaphrodite polar bears in the Svalbard area may be attributed to high levels of PCB affecting the sex hormones. PCB is banned in Western Europe but is still used in Russian energy production. Moreover, large quantities of PCB remain at European landfills. PCB is transported both by […] wind, sea currents and ice.

An investigation conducted by the National Environmental Research Institute of Denmark showed that many sea snails in the Danish waters suffer from imposex. Imposex includes sex change: female snails develop masculine characteristics such as penis and spermatic duct, thus the snails become pseudo[-]hermaphrodite. During the advanced stage, imposex means that the snails become sterile or die. In Denmark, all snails of the red whelk species suffer from imposex and at least eight other species have been affected. Imposex is closely related to the use of TBT (tributyltin). TBT is used as fungicide and algecide. Ship owners use TBT-containing anti-fouling paint to avoid algae. The endocrine disrupting effect of TBT is well documented both by lab tests and investigations [at] several places in close-shore waters. The substance is extremely dangerous: less than 0,5 nanogram/litre may cause imposex (1 nanogram= [a billionth of a] gram). In Danish waters, it is estimated that between 0,6 and 4,9 tons of TBT is released. This results in a concentration of TBT between 0,3 and 2,4 nanogram/litre under the presumption that the substance is divided equally and that it is not decomposed. These concentrations may explain imposex.

T. Lund, WORKING DOCUMENT 21.06.2000, Endocrine disrupting substances - Background paper, EUROPEAN PARLIAMENT, Committee on the Environment, Public Health and Consumer Policy, 1999-2004, http://www.europarl.europa.eu/meetdocs/committees/envi/20000710/413253_en.doc

Task 1 Explain briefly what types of problems are present in the cases described in the text (Lund 1999-2004) and how immissions of chemicals can get into the environment.

Solution to Task 1

It is a matter of reproduction and development problems resulting from so-called endocrine disruptors. Frequently, a feminisation of male organisms can be observed.

As described in the examples, emission can occur by an accident with chemical substances (dicofol) or by the distribution of chemicals which are brought into the environment as active ingredient (TBT as rot-proofing agent) or which have strayed from their area of activity (PCB as hydraulic fluid or softener). Sometimes it is not immediately apparent that substances are problematic. This includes effects which were not known at the time of the initial commercial application, e.g. chlorofluorocarbons that destroy the ozone layer and softeners which turn out to be endocrine disruptors.

Further ways of immission include the unintended release of substances during disposal (gases and particles from incineration or leachate from landfill sites or from wrecking yards of electrical waste (refrigerators, computers, etc.) or ship, plane and car dumps).

2 Environmental compartment water

Within the course of an experiment (Kidd et al. 2007), low concentrations (5-6 ng∙L1, which is about a factor of ten higher than the worst case estimates and monitoring data for environmental concentrations (Kidd et al. 2007)) of the estrogen 17α-ethynylestradiol were added to a North American lake in the years 2001 to 2003 in order to examine the effect on the population of fathead minnows (Figure 1).

A reduced development of gonads and delayed spermatogenesis (development of male gametes) as well as a production of vitellogenin and development of fibrosis (increase of conjunctive tissue) were documented. Vitellogenin was produced by female fish beyond the breeding season.

Figure 1 Fathead minnow

Task 2

a)  Speculate as to why and with which aim the experiment was conducted.

b)  Life expectation of fathead minnows is about two years, but they can live as long as four years. Their sexual maturity is reached in the second year, and they spawn in early summer within a time frame of two months. Several females spawn in the same nest of one male fish, which cares for the spawn until hatching. Fathead minnows are an important food source for many predatory fish such as lake trout, walleye, and northern pike. Regarding the observations that were made in this experiment, explain what could happen as a consequence.

Solution to Task 2

a)  The substance applied in the field experiment is a synthetic estrogen, i.e. it is not one of the typical representatives of chemicals that are expected to be found within an analytic sample such as agrochemicals or biocides. Synthetic estrogens in the environment result from the consumption of birth control pills. The fact that one expects to find them in a water body conveys the knowledge that they can find their way into the aquatic environment with municipal wastewater. A low experimental concentration should correspond to treated and untreated municipal wastewater in order to examine potential effects of human activities on the environment.

b)  Fathead minnows spawn in early summer and spawn only once during that time. As the majority of fish does not live longer than two years, many fish spawn only once in their lifetime. When delayed spermatogenesis causes reproductive failure in two successive years, the fish population can collapse for lack of young animals. Corresponding to a single spawning, the following generations produce less young animals. Although several thousand eggs will be fertilised, many fish fall prey to the mentioned predatory fish. Thus, sufficient spawning is necessary in order to maintain the population. One of the results of the experiment was that due to feminisation of male animals the population collapsed and only few young animals could be captured. Life-historical characteristics such as life span are important factors of a species’ risk when exposed to estrogens or estrogen mimics. In order to avert negative consequences, society has to find a solution. A possible adverse effect on predatory fish due to decreased food availability was not examined in this study.

3 Pharmaceuticals - chemistry’s blessing

Pharmaceuticals (Figure 2) are applied in order to detect diseases (diagnostics), to do therapy with (Figure 3), to treat (e.g. infections (e.g. with antibiotics)) and to prevent disease. One of the most common drugs is, for example, acetylsalicylic acid (Figure 3c).

Throughout history, much progress has been made in research concerning pharmaceuticals, e.g. discovery of the antibiotic Penicillin. However, pathogens evolve and assimilate. Therefore, pharmaceuticals have to be modified while maintaining their effect or similar substances have to be found.

Pharmaceutical companies are searching for innovative or optimized drugs for current problems such as AIDS, Alzheimer’s disease and cancer, e.g. effective cytostatic drugs in order to inhibit the ability of cancer cells to proliferate. However, pharmaceuticals are active substances also bearing the risk of negative effects. These have to be identified and the benefit to risk ratio has to be considered.

Figure 2 Pharmaceuticals

a) b) c)

Figure 3 Chemical structure of a) Metoprolol, used for the treatment of heart attacks and hypertension; b) Oseltamivir, used for treatment of viral flu; c) acetylsalicylic acid, applied for its analgesic, anti-inflammatory, antipyretic and antiplatelet effect.

Definition (31 March 2004) of a medicinal product:

(a) any substance or combination of substances presented as having properties for treating or preventing disease in human beings; or

(b) any substance or combination of substances which may be used in or administered to human beings either with a view to restoring, correcting or modifying physiological functions by exerting a pharmacological, immunological or metabolic action, or to making a medical diagnosis.

Task 3 Establish a mindmap, which presents as many facets as possible regarding the topic “Pharmaceuticals”. One of them is environmental compatibility.

In contrast to environmental pollutants such as biocides, volatile organic compounds, heavy metals, etc., pharmaceuticals represent a special class of chemicals. They are an integral part of a dignified life and possible environmental risks cannot be met by common modes of action, e.g. restrictive covenants or even banishment. Measures for the mitigation of their environmental risk have to be multifaceted. Therefore, the worksheets deal with their occurrence patterns and possible scopes of action. On the part of legislation, a guideline on the environmental risk assessment of medicinal products for human use was passed (Committee for Medicinal Products for Human Use 2006).

Solution to Task 3

(This mindmap is a proposal. Of course, many additional aspects could be considered as well.)

4 Pathway of human pharmaceuticals into surface waters

The investigation (Kidd et al. 2007) of the effects of the synthetic estrogen ethynylestradiol on fathead minnows showed a sensitive reaction of the fish population to the active ingredient of birth control pills. Concentrations of 5-6 ng∙L1 within a chronically contaminated water body were already sufficient to influence the fish hormonal system, causing reproduction problems, and, thus, endangering the maintenance of the population.

Not only estrogens but also other pharmaceuticals can be detected in water bodies. In the following, the subject is how they can get there.

Parent compounds and metabolites of pharmaceuticals pass through kidney and liver and are excreted via urine and/or feces. Furthermore, there are often leftover drugs which are sometimes (illegally) disposed of via the toilet when they have expired (Figure 4a). In old, damaged sewer systems part of the pharmaceuticals passes directly into the groundwater with the sewage. The main part certainly arrives at the waste water treatment plant. However, even in the waste water treatment plant not all pharmaceutical residues can be removed. Thus, they are transported with the effluent into surface waters such as lakes and rivers or they remain in the biosolid, which is either disposed of or applied in agricultural areas.

The general composition of today’s municipal waste water treatment plants (Figure 4b) can be subdivided into three treatment stages:

1. mechanical purification; 2. aerobic degradation (by means of microorganisms); 3. nitrogen and phosphate elimination.

Figure 4 a) Representative survey: one out of seven German citizens at least occasionally disposes of unused or expired tablets via the toilet (2008) b)Composition of a waste water treatment plant. With kind permission from Hach Lange GmbH, Willstätterstraße 11, 40549 Düsseldorf (Germany).

1. Sewer
2. Rain basin
3. Bar screen / grit chamber
4. Primary clarifiers / settling tank
5. Activation basin / 6. Secondary clarifiers
7. Filter
8. Thickener
9. Sludge dewatering
10. Digester

Task 4 Sewage plants treat wastewater mechanically and biologically. In some plants there is an additional charcoal basin, not pictured here.

a)  Allocate the following terms to the stations of the treatment plant: sieving; sedimentation (e.g. by reduction of the flow velocity); oxidation; filtration; adsorption

b)  Allocate where the following matters are removed: coarse, solid particles; sand; unsolved particles; organic components; solved chemicals; microorganisms

Solution to Task 4

Treatment procedure / Removal of
1. sewer
2. rain basin
3. bar screen / grit chamber
4. primary clarifiers / settling tank
5. activation basin
6. secondary clarifiers
7. filter
8. thickener
9. sludge dewatering
10. digester
charcoal (not shown in the diagram) / sieving
sedimentation
oxidation
sedimentation
filtration
adsorption / coarse, solid particle
sand; unsolved particles
organic components
microorganisms
unsolved particles
organic components
solved chemicals

Comment: many pharmaceuticals will not be oxidized / mineralized (to a high extent) in a wastewater treatment plant. The application of charcoal reduces the effluent of chemicals such as drugs and their metabolites.

5 Waste water treatment plants and drugs

Figure 5 shows the total contamination by drugs in the influent and effluent of seven wastewater treatment plants. The degradation rates vary and depend on different parameters.

Figure 5 Total load of measured pharmaceuticals in grams per day and per 1000 inhabitants (INH) of seven Spanish municipal wastewater treatment plants (WWTP) and their respective degradation rates (Gros 2010, personal communication). In WWTP3 and WWTP4 industrial wastewater is also treated.
Task 5 Discuss the influence of residence time on degradation rate.
Residence time of water [h] / 32 / 18 / 8 / 25 / 10 / 6-10 / 33
Degradation rate [%] / 90 / 47 / 0 / 88 / 44 / 27 / 76

As drug concentration in the effluent is by far higher (within the scope of a magnitude) than in the rivers in which it is released, the wastewater treatment plants represent point sources that make a special treatment worthwhile. Drugs can be adsorbed by charcoal and other carrier materials such as an Mg-Al layered double hydroxide in order to remove them from wastewater. Another retention process is (ultra)filtration. Apart from that, oxidants can be employed to degrade drugs by oxidation (Figure 6).