The Pharmaceutical Journal
Vol 280 No 7488 p154
9 February 2008

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Effect of sonar on whales

Oxalic acid — the beekeeper’s friend

Many ways in which pets can be poisoned accidentally

Effect of sonar on whales

Conservationists have recently highlighted incidences of whales being stranded in hotspots around the world, including an area between the north east coast of Scotland and Norway, as a direct result of excessive noise from both military and commercial activity.

The phenomenon was first postulated several years ago and reported in such publications as National Geographic and Nature.

Acoustic transmitters send sonar waves which, to whales, sound like the launch of a twin-jet engine. The sound waves are swept across hundreds of miles of ocean to detect underwater activity, and remain at harmful levels up to 100 miles from the sonar system.

The sounds can affect the whales’ ability to navigate, avoid predators and care for their young. The sonar signals can also cause bubbles to form in the tissues of the whales, in a similar way to that which causes divers to suffer decompression sickness. Post-mortems reveal damage to the animals’ liver and kidneys, including gas-filled cavities. The whales become distressed and strand themselves upon the shoreline, resulting in a slow death.

Deep-diving species, which include some of the most endangered, are the most affected, such as the Western Grey Whale, whose numbers are placed at fewer than 100 worldwide. Their diving profiles means that they absorb more nitrogen into their tissues, and are therefore more at risk when they surface.

What is still unclear is whether the sound waves are damaging the animals’ tissues directly, or whether they are frightening the whales into making too rapid an ascent, with the same results.

While the whaling industry lobbies — both for and against hunting — make headlines for the industry’s potential to deplete stocks of species already at dangerously low levels, the damage caused by sonar, although not as widely publicised, must also be seriously considered.

Conservationists insist that more research is needed to establish a safe level of sonar activity for the cetaceans, to avoid further depletion in the populations of some of the most threatened mammals on the planet.

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Oxalic acid — the beekeeper’s friend

Over the past 15 or so years, scores of ethical products and packed goods have vanished from wholesalers’ price lists, and products that were once ordered by the dozen, such as boric acid crystals and powdered alum, are now nigh on impossible to source.

One such product, however, is enjoying something of a renaissance in certain circles. Oxalic, or ethanedioic acid, is a white crystalline solid occurring naturally in many plant species, including spinach and rhubarb leaves, and its most common uses are in the tanning of leather, the bleaching of wood and in stain removal, where it acts as a reducing agent.

Recently, however, the development of resistance of the varroa mite, a major parasite of the honeybee, to the pyrethroid group of varroacides, has meant that the more traditional treatment using oxalic acid, which had fallen from favour in the light of the newer pyrethroids, has been incorporated into a programme of integrated pest management used throughout Europe, the US, and New Zealand.

A dilute solution of oxalic acid (6 per cent in a 30 per cent sugar solution) is drizzled in between the frames of the brood chamber of the hive after the honey has been harvested, and this delivers a small dose of oxalic acid onto the bees, which has two effects upon the mites.

First, it damages the claspers on the proboscis of the mites, preventing them from sucking the haemolymph from the bees and, secondly, the acid damages the mites’ respiratory apparatus, which kills them. Treatment with oxalic acid does not result in the death of all of the mites, but has been reported to kill approximately 90 per cent of varroa mites on adult bees, which keeps them at a level which will not harm the colony.

The British Beekeepers Association recommends, however, that due to the hazardous nature of oxalic acid, beekeepers purchase ready-made solutions from beekeeping suppliers, so pharmacists may still be left with that dusty jar of Ac Oxalis on the uppermost shelf of the far stockroom.

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Many ways in which pets can be poisoned accidentally

One morning last summer my wife asked me to look at our pet rabbit, because she feared it had died during the night as it had not emerged from its sleeping area, which was customary behaviour when fresh food and water was offered. On investigation I discovered that it was not dead, but its breathing was shallow and it was not otherwise moving, so I told the family to brace themselves for the worst.

The following morning, when I went out to inspect the hutch, a Lazarus-like resurrection appeared to have taken place, and the previously stricken animal was bounding around as though nothing had happened. This was puzzling, until I noticed some containers near to the hutch containing the remnants of plants which had been chewed, presumably by the rabbit when it had been let out to exercise.

The most severely damaged plants were pansies and ornamental ivy of the genus Hedera, which further research revealed to be a plant reported to be toxic to a variety of animals upon ingestion.

Ivy is not the only commonly encountered substance harmful to household pets; there is a host of other products that can be dangerous to a greater or lesser extent.

Most dog owners are aware of the dangers posed by feeding their animals chocolate treats, as the drugs theobromine and caffeine are harmful even in moderate doses, and the appealing nature of chocolate often leads to overdose, particularly at Christmas and Easter time.

Symptoms include vomiting, excessive urination, fast breathing, weakness, and seizures. Although rare, death can occur due to the adverse reaction of methylxanthines on the heart.

Grapes and raisins are also highly toxic to dogs, and only six or seven raisins, in small animals, can lead to tremors, vomiting, diarrhoea, lethargy, reduced urination, and kidney failure, which sometimes results in death.

Onions and garlic can also cause the above symptoms in dogs, even in the small amounts used to flavour baby foods.

Xylitol, used as a sugar substitute in many foods, is highly toxic to dogs, and a small amount can cause too much insulin to be released, causing a drop in blood sugar which can result in liver failure and death.

There has been an increase in the incidence of toxic reactions in cats in recent years caused by lilies of the genus Lilium. All parts of the lily are extremely toxic, and one of the easiest ways for cats to be affected is by brushing against the flowers, then licking the pollen off their coats.

Symptoms of poisoning include vomiting and depression, but the most severe effect is upon the kidneys, which can cease functioning within 18 hours, causing death.

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