Synanthropic primates in Asia: Potential sentinels for environmental toxins

Abstract

Macaques are similar to humans both physiologically and behaviorally. In South and Southeast Asia they are also synanthropic, ecologically associated with humans. Synanthropy with humans raises the possibility that macaques come into contact with anthropogenic toxicants, such as lead and mercury, and might be appropriate sentinels for human exposures to certain toxic materials. We measured lead (Pb) and mercury (Hg) levels and characterized the stable isotopic compositions of δ 15 N and δ 13 C in hair from three groups of free-ranging macaques at the Swoyambhu temple in Kathmandhu, Nepal, an urban population that has abundant contact with humans. Hair lead levels were significantly higher among young macaques and differed among the three groups of macaques that were sampled. Hair Hg levels were low. No statistical association was found between stable isotopic compositions (δ 15 N and δ 13 C) and Pb and Hg levels. Our data did not find evidence that lead levels were associated with diet. We conclude that, in this population of macaques, behavioral and/or physiologic factors may play a significant role in determining exposure to lead. Chemical analysis of hair is a promising, noninvasive technique for determining exposure to toxic elements in free-ranging nonhuman primates. Keywords lead; macaque; ecotoxicology; mercury; synanthropic Over the past decades the public's increasing awareness of the potential adverse health effects of anthropogenic (human-derived) pollutants has prompted efforts to better detect environmental hazards and promote an understanding of the routes and mechanisms by which toxicants exert their adverse health effects. Ecotoxicologists have gained insight into these phenomena using wildlife as models for ecological and physiological effects (e.g., ecosystem health). Various animal populations have been proposed as "sentinels" for human exposure to toxicants present in the environment. (Aguirre et al., 2001). These "canaries in the coal mine" can potentially help to identify toxic threats to both public health and wildlife populations. Not all animal species are relevant models for human toxicant exposures. The utility of an animal population as a sentinel depends on many factors, including its genetic and physiological characteristics and how closely its ecological niche mirrors that of sympatric human populations (Aguirre et al., 2001). In South and Southeast Asia, free-ranging macaques (genus Macaca), particularly rhesus (M. mulatta) and long-tailed macaques (M. fascicularis), are often synanthropic with humans, meaning that they flourish in ecological niches created when humans alter the environment (Southwick and Siddiqi, 1994;Sha et al., 2009;Fuentes, 2007;Jones-Engel et al., 2006, 2007Engel et al., 2006;). Macaques also share important immunological and physiological similarities with humans, particularly in the ways in which they respond to toxic exposures ( Reuhl et al., 1989;Rice, 1992: Levin et al., 1988. All of these factors contribute to making macaques potentially valuabl...

Characterizing the Picornavirus Landscape among Synanthropic Nonhuman Primates in Bangladesh, 2007 to 2008

“…The potential for cross-species transmission exists wherever humans and NHP come into contact. Human-NHP interaction is common in Asia, particularly in Bangladesh, where humans and NHP have lived sympatrically for centuries (6)(7)(8)(9). The contexts of contact between humans and NHP in Bangladesh are a microcosm of what is seen in much of South and Southeast Asia.…”

Lead levels in long-tailed macaque (Macaca fascicularis) hair from Singapore

“…Hair was plucked using gloved hands, placed into sterile 15 mL plastic tubes, and stored in a cool, dark place. Research has indicated significant variation in macaque hair growth (Engel et al 2010). Following recent work on lead levels in macaque hair (Engel et al 2010), we assume that an average hair sample represents approximately 100 days of growth (approx.…”

“…Research has indicated significant variation in macaque hair growth (Engel et al 2010). Following recent work on lead levels in macaque hair (Engel et al 2010), we assume that an average hair sample represents approximately 100 days of growth (approx. 50 mm of hair with an estimated average growth rate of 0.5 mm per day).…”

“…Despite their suitability as sentinels, our search of the literature revealed only two published articles focusing on lead concentrations in wild populations of nonhuman primates. A study by Engel et al (2010) reported low to moderate hair lead levels in rhesus macaques from the Swoyambhu temple in Kathmandu, Nepal. A second study on ring-tailed lemurs at Beza Mahafaly Special Reserve in Madagascar failed to detect lead in hair samples (Rainwater et al 2009).…”

“…Digests were then diluted to 15 mL with ultrapure water. Lead (Pb) concentrations were measured using methods described in Engel et al (2010) and Moses et al (2009). Between 0.005 and 0.02 g (approx.)…”