Other Evidence on Bird Keeping and Lung Cancer

Abstract

There are regional differences in the Netherlands in male lung cancer mortality (Table 5.1) that cannot be explained by the differences in the age distribution of the population (Hoogendoorn 1983). Unfortunately, regional information about smoking habits is not available. The rural province of North Brabant had, in 1984, the highest age-standardized lung cancer mortality. This province contains three towns among the eight largest municipalities with the highest lung cancer mortality in the Netherlands. Tilburg and Maastricht had the highest standardized lung cancer mortality among the eight largest municipalities for the years 1969–1978 (CBS 1980). Tilburg also had the highest mortality in 1984. Most of the bird clubs and most of the organized bird keepers are traditionally found in North Brabant. The number of organized bird breeders of the Netherlands society of bird lovers grew dramatically from 1400 in 1940 to 45 800 in 1984. The incidence of lung cancer was quite low in the Netherlands until 1950. In 1950, 1179 men and 167 women died from this disease. By 1983, the numbers had increased to 7104 men and 800 women. Standardized for age, the mortality per 100 000 men increased from 27 to 120 between 1950 and 1988 (Table 5.2) and per 100 000 women from 3.3 to 10.6 over the same period. Since 1975, the percentage of male smokers over 35 years of age has declined from 70% to under 50% (Baan 1986; see Table 5.3). A slight decline in smokers has also occurred among women since 1975. In the period 1975–1983, taking into account the aging of the population, the number of newly diagnosed cases in women of cancer of the trachea, bronchus and lung has increased by 73% and mortality by 58%.