5 September 2011
Eyes itching, feel a sneeze coming on? Remember seeing clouds of pollen floating from nearby pine trees?Many early spring hay fever sufferers join the dots and assume that the forest industry's workhorse, good old Pinus radiata, is to blame for their misery.
Retired Massey University associate professor David Fountain says pine pollen can cause mild hay fever, but it doesn't deserve its bad reputation.
"The pollen grains from all pine species are very large and are produced in big quantities. But they are weak allergens and because of their size, they don't penetrate very deeply down the branches of the airways."
Dr Vincent Crump, director of the Auckland Allergy Clinic, says it's his experience that very few patients have clinically significant skin prick test reactions to pine pollen. However, if a large amount of pine pollen is inhaled, it may cause irritation.
The main tree pollen to cause allergic symptoms in New Zealand comes from silver birch. It starts being shed in mid-September in Northland and about three weeks or a month later in Southland.
"Even though the birch pollen season is short it commonly causes cross-reactions to fruits, peanuts and soy in patients who are allergic to birch pollen. They develop oral allergy syndrome – an itching inside the mouth when they eat fresh fruits, especially apple."
Dr Fountain is the author of a pollen forecast that appears on the Met Service website from October each year. He says birch pollen starts being shed at around the time the radiata pollen season ends.
"Birch pollen is a very potent allergen and is recognised as such in the northern hemisphere. But because its grains are not as large and visible as those from pines, pines are often unfairly blamed for their ill-effects."
Deciduous trees like birches have pollen seasons of about three weeks. And while they may make the lives of some hay fever sufferers miserable, the period is too short to justify tree removal, Dr Fountain says.
"Besides, our major pollen allergen producers are grasses. Their peak is just before Christmas and cause about 20% of the population to have a miserable late spring and early summer."
What then should you do with the drifts of yellow pine pollen that coat your car and driveway? If it doesn't cause you hay fever, can you make use of it in some way?
Internet-based marketers claim pine pollen is ultra-rich in vitamins and minerals, raises testosterone, lowers cholesterol, improves libido, combats nappy rash and contains a steroid that combats breast and prostate cancer.
"Not so fast," says Glen Mackie of the Forest Owners Association.
"None of the health benefits of pine pollen have ever been scientifically proven, so it's illegal in New Zealand, the United States and elsewhere for pollen marketers to make therapeutic claims about their products. And while there are no known harmful effects arising from pollen consumption, that's not to say the pollen on your driveway is safe to eat.
"If you don't like your drive to have that golden look, just hose the pollen down the drain."
For more information, please ring Dr David Fountain, Tel 06 326 8428; Dr
Vincent Crump, Tel 09 376 6185; or Glen Mackie Tel 04 473 4769