Severe Dental Fluorosis in Juvenile Deer Linked to a Recent Volcanic Eruption in Patagonia

Abstract

ABSTRACT:The Puyehue-Cordon Caulle volcanic eruption deposited large amounts of tephra (ashes) on about 36 million ha of Argentina in June of 2011. Tephra was considered chemically innoxious based on water leachates, surface water fluoride levels were determined to be safe, and livestock losses were attributable to inanition and excessive tooth wear. To evaluate effects on wild ungulates, we sampled wild red deer (Cervus elaphus) at 100 km from the volcano in SeptemberNovember 2012. We show that tephra caused severe dental fluorosis, with bone fluoride levels up to 5,175 ppm. Among subadults, tephra caused pathologic development of newly emerging teeth typical of fluorosis, including enamel hypoplasia, breakages, pitting, mottling, and extremely rapid ablation of entire crowns down to underlying pulp cavities. The loss of teeth functionality affected physical condition, and none of the subadults was able to conceive. Susceptibility to fluorosis among these herbivores likely resides in ruminant food processing: 1) mastication and tephra size reduction, 2) thorough and repeated mixing with alkaline saliva, 3) water-soluble extraction in the rumen, and 4) extraction in the acidic abomasum. Although initial analyses of water and tephra were interpreted not to present a concern, ruminants as a major component of this ecosystem are shown to be highly susceptible to fluorosis, with average bone level increasing over 38-fold during the first 15.5 mo of exposure to tephra. This is the first report of fluorosis in wild ungulates from a volcanic eruption. The described impact will reverberate through several aspects of the ecology of the deer, including effects on population dynamics, morbidity, predation susceptibility, and other components of the ecosystem such as scavenger and plant communities. We anticipate further impact on livestock production systems, yet until now, existence of fluorosis had not been recognized.

Impacts to agriculture and critical infrastructure in Argentina after ashfall from the 2011 eruption of the Cordón Caulle volcanic complex: an assessment of published damage and function thresholds

“…However, the main cause of livestock losses across the impacted area was due to starvation and gastrointestinal blockages. Some livestock were also affected by skin and eye irritations and infections (Robles 2012), possible chronic fluorosis (Flueck & Smith-Flueck 2013;Flueck 2014;Flueck 2013), and in Jacobacci there was a decline in wool quality and shearing rates (Aguirre 2012;Easdale et al 2014;Wilson et al 2012b).…”

Temporal kinetics of fluoride accumulation: from fetal to adult deer

“…The low fluoride levels in fetal deer bones reported here, therefore, also indicate a placental barrier, particularly considering that concentrations in mothers were 109-fold higher. As expected, calves showed unaffected mandibular molars M1, which mineralize in utero and are established in 4-month-old calves (Flueck and Smith-Flueck 2013). Kay et al (1976) also found that skeletal fluoride levels in wild ungulates at birth were near zero.…”

“…In contrast, antlers shed in 2012 in one area and from males subjected to fluoride exposure averaged 657 ppm (Flueck and Smith-Flueck 2013). …”

“…Livestock losses in the region are still attributed to emaciation and excessive tooth wear, rather than to known toxic elements (Wilson et al 2012). However, recently, wild red deer (Cervus elaphus) at 100 km from PCCVE and livestock as far as 222 km were found to be strongly affected by fluorosis (Flueck 2013;Flueck and Smith-Flueck 2013). Based on fluoride concentrations from deer sampled in 2009, the average level of fluoride increased 38-fold among severely affected deer sampled about 16 months after the eruption, with maximal levels of 5,175 ppm in dry bone.…”

Brief communication: Extended chronology of the Cordón Caulle volcanic eruption beyond 2011 reveals toxic impacts

“…1a). Furthermore, fluoride concentrations in bone approached 5180 ppm, whereas the average level increased more than 3900 % after exposure to tephra for the first 15.5 months (Flueck and Smith-Flueck, 2013a). Furthermore, fluoride concentrations increased substantially in four age classes, at a rate of about 1000 ppm of F yr −1 on average.…”