The investigation of a high incidence of arthritis in 21 dairy herds disclosed elevated fluorine levels in bone samples. In every herd except one, where herbage and water was contaminated by industrial fall-out, the main source of the fluorine was from mineral supplements. In a few herds, purchased cake or grain balancers contributed to the abnormal levels. Over 100 cows with arthritis had fluorine levels in the bone of between 2000 and 8000 ppm, or were in herds whose diet contained excess fluorine. Characteristic tooth lesions often confirmed the link between arthritis and fluorosis.
Sixteen out of 31 samples of mineral supplement contained dangerous levels of fluorine (3000 to 13000 ppm). Grain balancers contained up to 400 ppm F, and dairy cake had leveles as high as 140 ppm F.
There was a statistical correlation between a high incidence of damage to peri-articular structures, resulting in debility and loss of production, and elevated bone fluorine.
In 1934 there was a report from the United States (Phillips and others) of chronic fluorosis in cattle resulting from the use of rock phosphate. In Great Britain fluorsis arising from atmospheric pollution was reported by Blackmore and others in 1948 and Burns and Allcroft in 1964. Most of the references in the literature reported cases occurring as a result of industrial contamination of herbage, drinking water with a high fluorine content, or experimentally fed sources of fluorine (usually sodium fluoride). There was, in comparison, less literature relating to rock-phosphate induced fluorosis – especially in Great Britain. In fact, Burns and Allcroft stated that in Britain it was not customary to use raw rock phosphate as a source of phosphorus in mineral mixtures and therefore the potential hazard from this source was small. The position since 1964 has altered dramatically with the incorporation into cattle rations of rock phosphates from less traditional sources where the levels of fluorine were dangerously high.
Mineral mixtures with levels of up to 13,000 ppm F were recorded during the study here reported. These provided more than twice the maximum safe daily intake of fluorine when fed at 3 per cent of the concentrate ration. The maximum safe level was accepted as 60 to 100 ppm F in the total ration (Phillips and others 1960) when the fluorine was derived from phosphate.
Mineralized protein grain balancers with levels of fluorine of about 400 ppm F were reported (Burns and Allcroft 1964) which contributed (if fed at 50 per cent of the production ration) between 50 to 100 ppm F to the total ration.
In recent years outbreaks of fluorosis in dairy cows due to contamination of their feed have been investigated by the Central Veterinary Laboratory, Weybridge. A survey of fluorine levels in the tailbones of cattle in Cheshire (Lloyd 1973) showed that a third of the samples contained above 2000 ppm F compared with 1000 ppm F in animals receiving fluorine from natural sources. A second feature of the report was the number of cases of hip lameness in which fluorine was probably implicated. This was not a feature of the classical form of fluorosis reported in experimental studies, or industrial cases.
… The long term ingestion by dairy cattle of elevated fluorine in mineralised concentrate which has occurred since 1964 has produced a new clinical condition: hip arthritis on a herd basis. The number of cattle exposed to excess fluorine in the 21 herds represented over 15 per cent of the cattle population in the practice area; the fluorine was found in the products of some companies operating on a national scale. It is thus possible that fluorosis occurred in other areas, but was either not recognised, or, not reported. Many cattle in the national herd could have been exposed to excess fluorine. The report of Lloyd (1973) on bone samples recorded from abattoirs confirmed abnormal intakes in cattle in Cheshire. Acceptance of the European Economic Community directive on permissible levels of fluorine in the total diet will ensure that dairy cattle are protected from its adverse effects.