11.08.2006

Cannabis adversaries While the consumption of tobacco and alcoholic beverages continues to be legal way to increase the national tax revenue of many governments worldwide, the use of cannabis products in the US and other countries is mostly illegal, but continues to cause controversies. According to an article in the Harm Reduction Journal an estimated $4 billion is spent in the US on the arrest, prosecution and incarceration of marijuana offenders each year. Marijuana arrests now constitute nearly half (45%) of the 1.5 million drug arrests in the US annually. Proponents for the legalization of cannabis have been claiming its harmlessness for years. They have only recently been joined by pain physicians who see a great protential of cannabis receptor agonists to relieve severe, otherwise intractable pain. Cannabis receptors have been found in many tissues, and anandamide (Figure 1), a well-known physiologic agonist (a chemical that triggers the receptor in the body), has attracted interest of biochemists and physiologists alike. Currently suggested medical uses of cannabis are (1) AIDS (reduces nausea, vomiting, waste syndrome), (2) Cancer (alleviates nausea, vomiting from antineoplastic chemotherapy), (3) Glaucoma (reduces intraocular pressure), (4) Multiple Sclerosis (decreases muscle pain and spasticity), (5) pain (alleviates chronic pain that may be intractable otherwise). Figure 1: The chemical structure of the physiological CB-receptor agonist anandamide Opponents continue to argue that Cannabis (1) produces dependence after chronic abuse, (2) acts as a gateway drug, and (3) is associated with a higher incidence of psychosis than non-cannabis users. Other concerns include (5) decreased intellectual performance, (6) a higher risk for heart attacks, (7) the promotion of tumor growth and (8) the impairment of anti-tumor defenses by marijuana ingredients. The risk for cannabis dependence (around 10%) is lower than that for other social drugs (alcohol, nicotine), but withdrawal symptoms have been reported by 80% of the male and 60% of the female abusers seeking expert help to stop cannabis consumption. Regular users of cannabis are more likely to eventually switch to heroin, cocaine and other psychotropic drugs than are other people, although other reasons like special social environments may contribute to this observation. The risk of experiencing psychotic symptoms is increased in adoslescents who use cannabis products more often than weekly. Recent headlines indicating an adverse effect of marijuana on sperm motility may again move the scales. In spite of these controversies a large body of experimental and clinical data has established a role for cannabis drugs in the treatment of several disorders, and at least three different presecription drugs with marijuana ingredients (Figure 2) are available in many countries of the world, including the US. While several countries like Germany and Switzerland require special prescription forms, a doctor in the US may phone in the presecription. In the Netherlands there is even less control over cannabis use in the general population because the Dutch government has made a distinction between hard (opiates, cocaine, ecstasy) and soft drugs (psilocybin mushrooms, marijuana), allowing the sale of the latter for explicit personal use in public "Coffee Shops". Figure 2: Chemical structures of three synthetic medical cannabinoid drugs Recently experts of the US Food and Drug Administration (FDA) puzzled physicians worldwide by declaring that "no sound scientific studies" support the medical use of marijuana. Experts at the Medscape Forum spoke out what others thought, namely that once again "Politics Trumps Science at the FDA". I foresee that this turn may be shortlived because too many scientists know better and too many organisations successfully support the research on medical uses of cannabis - even in the US. For many seriously ill patients, however, this official move may be detrimental because it may also impede the prudent use of cannabis drugs that has been advocated by pain physicians for many years. -+HM+- 3:29:05 PM

12.03.2006

Snowmelt and Toxicology With pictures of roofs cracking under masses of snow on TV in Europe and Northern America it is time to focus on the impact of snowmelt on aquatic ecosystems. Snowmelt when augmented with rain is not only a heavy load on roofs but also a load for influenced rivers and lakes which are to receive the contained pollutants. After several months of frost airborne deposits that have been conserved in the snow masses, and soil matter that has been disrupted by ice are now leached into the run-off, sometimes within a few days. This allows certain toxic solutes to enter the aquatic environment. Foto by J Reynolds, with permission It has been shown as early as 1978 that arsenic gets mobilized from soil and the arsenic burden rises in Texas (-> Richardson &&, J Environ Qual, 7(2): 189-192) and elsewhere each year, due to the geologic occurrence of the element. Apart from heavy metals (e.g. aluminum, cadmium, chromium, copper, kead, zinc) other toxic pollutants like oil and grease, hydrocarbons, can be detected. Compared to ordinary rain snowmelt is more acidic. It will mobilize many pollutants that would stick to soil under more alkaline conditions, e.g. aluminum and other (toxic) metals. In addition it contains all the dust and fallout that has been accumulated in the snow since last rainfall (sometimes from several months) and keeps it frozen until melting mobilizes and concentrates the matter from the large snow masses down to a thin surface film. When the melted snow starts running off to nearby creeks and lakes it will likely mess up the affected ecosystems. As a result fish die-off and other more subtle changes will occur and propagate until becoming more and more diluted. Sometimes several adverse accidents combine as happened to the Hungarian river Tisza in March 2000, when snwomelt and heavy rain caused a dam break of an upstream mine tail settling pond and release highly toxic cyanide and heavy metal salts into the environment. There are several areas where such pollutants have to be strictly avoided. Such sensitive areas include: Coastal Counties ‡ to protect sensitive coastal waters Water Supply Watersheds ‡ to protect waters that are used as drinking water supply sources High Quality Waters and Outstanding Resource Waters ‡ to protect waters that have unique water quality or unique resources. Nutrient Sensitive Waters ‡ to reduce the inputs of nutrients from urban and developing areas. There is also a US federal program (the National Pollutant Discharge Elimination System (NPDES) Stormwater Program) that requires stormwater permits for point source discharges of stormwater from certain industrial activities and from large municipalities (population 100,000 or larger). Other countries have issued their own regulations how to deal with snowmelt (and storm waters), but the issue recurs every year, inflicting severe damage on ecosystems and dependent economies. What can be done? A recommended remedy whereby the impacts of snowmelt runoff on aquatic systems can be minimized is by storing snow in upland areas to promote infiltration, more nearly approaching pre-development hydrology. It also provides an alternative to disposing of snow directly into streams, reducing the capacity for "shock" loadings. -+HM+- 2:44:01 AM