Heavy metals in the hair of opossum from Palo Verde, Costa Rica.

Levels of lead, cadmium, mercury, chromium, and manganese were measured in the hair of opossum (Didelphis virginiana) from Palo Verde, Guanacaste, Costa Rica. This area has some agriculture, but is slated for extensive water development that will increase ecosystem exposure to a variety of agricultural chemicals. Metal levels were generally not intercorrelated except for chromium and lead, chromium and cadmium, and cadmium and lead. There were significant gender differences only for lead and chromium, with the significantly smaller females having higher levels. It is suggested that hair from mammals, particularly abundant ominivores may be useful, bioindicators of environmental quality over a long time period.

Heavy metal and selenium levels in endangered wood storks Mycteria americana from nesting colonies in Florida and Costa Rica.

Colonially-nesting birds often nest in coastal areas, along rivers, or near other bodies of water that also are potentially polluted from industrial, agricultural or urban development. The levels of heavy metals and selenium were examined in the feathers of young wood storks Mycteria americana nesting in Northeastern Florida and from adult and young storks nesting on the Tempisque River on the west coast of Costa Rica. There were no significant yearly differences among the chicks from Costa Rica. Concentration of mercury, cadmium, and lead were significantly higher in the chicks from Florida compared to those from Costa Rica. Adult wood storks at Costa Rica had significantly higher levels of lead, cadmium, selenium, and manganese than young from the same colony.

Fishing in contaminated waters: knowledge and risk perception of hazards by fishermen in New York City.

Risk perception studies show that people may underestimate significant risks while overestimating others. Further, government agencies may assume the public becomes aware of risks when the agency has issued advisories, when in reality a segment of the population remains unaware of these warnings. This article reports on a survey of people fishing on the catchment basins of Jamaica Bay Wildlife Refuge in New York City. Of the 154 groups interviewed, only 19% believed the waters or fish were contaminated or unsafe, despite state warnings to the contrary. Fishermen made nearly five visits per month, and ate an average of three fish a week, (remaining fish were eaten by their families) and fish were usually fried. Most people believed the fish were safe to eat, or that they could recognize if one was spoiled. Thus, most people were ignoring the health advisories on consuming fish from these waters. We suggest that these fishermen are unaware of health advisories, or ignore them because the fishing situation is familiar, voluntary, pleasurable, and has not resulted in their illness. Since they believe they can determine if the fish are bad from smell and appearance, they have changed their own analysis from the unknown (chronic, delayed risks from toxics) to the known (immediate illness), lowering their perceived risk, but not the actual risk.

Heavy metal and selenium levels in young cattle egrets from nesting colonies in the northeastern United States, Puerto Rico, and Egypt.

Colonially-nesting species of herons and egrets breed mainly in coastal areas, along rivers or near other large bodies of water. Such areas are also preferred for human development, exposing nesting birds to various pollutants. From 1989-1991, the concentrations of heavy metals and selenium were studied in the feathers of fledgling cattle egrets Bubulcus ibis, a terrestrially-feeding insectivore, from New York and Delaware in the northeastern United States, from Puerto Rico, and from Egypt. There were geographic differences in the concentrations of lead, mercury, cadmium, manganese, selenium, and chromium in the feathers of these egrets. Lead levels were 41 times higher in the feathers of cattle egrets from Cairo compared to the other sites. This difference was attributed to the continuing use of leaded gasoline and the dense automobile traffic in Cairo. However, other differences remain unexplained. Similarly, levels of chromium and manganese were also higher in Cairo than at any other sites. Cadmium levels were similar at all places except for higher levels in eastern Puerto Rico. Mercury concentrations were twelve times higher in the feathers of cattle egrets at Aswan compared to Cairo. In Puerto Rico, we also compared levels in adult cattle egrets with young and found higher concentrations of mercury and manganese, but lower concentrations of selenium in the adults. Using feathers from young cattle egrets is a potentially sensitive tool for biomonitoring for metals, especially lead, since they reflect the local area surrounding the breeding colony.

Exposure assessment for heavy metal ingestion from a sport fish in Puerto Rico: estimating risk for local fishermen.

Sport or subsistence fishermen sometimes underestimate the risks from eating local fish and distrust authorities regarding potential hazards from fish. We report on lead, cadmium, selenium, and mercury levels in snook, locally called robalo (Centropomus spp.), consumed by local fishermen in Puerto Rico, who ate up to 23 fish/wk. Median levels (in ppb, dry weight) for muscle, adipose, and liver ranged from 683 to 780 for lead, 37 to 600 for cadmium, 50 to 146 for mercury, and 361 to 3986 for selenium. Lead levels were similar in all tissues, and selenium and cadmium levels were highest in the liver. Mercury was higher in muscle than in liver. Computing exposure via ingestion for the average fisherman indicated that if one were to consume robalo throughout the year one would be exposed in excess of the EPA Reference Dose (RfD) for mercury. Using a widely accepted maximum consumption of 200 g/d for fishermen yielded hazard indices (daily consumption/RfD) below 1 for all four metals, with a value approaching 1 for mercury in adults, and over 1 for 16-kg children. The possibility that in certain localities and cultures sport or subsistence fishermen may consume fish at levels substantially above 200 g/d should be investigated in performing risk assessments, particularly outside the continental United States.

Lead, mercury, and cadmium in feathers of tropical terns in Puerto Rico and Australia.

Levels of lead, cadmium, and mercury were examined in breast feathers of terns nesting on offshore islets near Culebra, Puerto Rico and on Michaelmas Cay and Heron Island on the Great Barrier Reef, Australia. Levels of all metals in these tropical terns were predicted to be lower than those of terns nesting in temperate regions, because the tropical species feed offshore of non-industrial areas where contamination should be less than for temperature-nesting species that feed in inshore estuaries near industrialized areas. This prediction was not supported by the evidence. In Puerto Rico, lead and cadmium levels were highest in bridled tern (Sterna anaethetus), and mercury levels were highest in sooty (S. fuscata) and roseate tern (S. dougallii). In Australia, levels of lead and mercury were higher in black noddy (A. minutus) and lower for sooty tern; and cadmium levels were highest for brown noddy (A. stolidus) and sooty tern, and lowest for black noddy. Metal levels for the tropical terns nesting in Puerto Rico and Australia generally were not lower than levels reported for temperate-nesting or mainland nesting birds (except for mercury in Australia).

Fishing a superfund site: dissonance and risk perception of environmental hazards by fishermen in Puerto Rico.

Risk perception studies show that individuals tend to underestimate significant risks, overestimate negligible ones, and distrust authorities. They also rely on a variety of strategies or heuristics to reach decisions regarding their risk-taking behavior. We report on a survey of fishermen and crabbers engaged in recreational and substance fishing in a Puerto Rican estuary (near Humacao), which has been declared a "Superfund site" because of suspected contamination by mercury, and at ecologically similar control sites. Nearly everyone interviewed at the Humacao site was aware of the mercury contamination, but either denied its importance, believed the contamination was restricted to a distant part of the estuary, or assumed that the estuary would be closed by the authorities if the threat was real. All site-users consumed the fish and crabs they caught. At Humacao, the average catch was 7 fish per fishermen (mostly tilapia, Tilapia mossambica, and tarpon, Megalops atlantica) and 13 crabs per crabber (all blue crabs, Callinectes sapidus). On average, the site-users returned to the lagoons about 3-4 times per month. At control sites, fewer fish were eaten. The worst case consumption of tarpon, a species which concentrated mercury at Eastern Puerto Rico, provided an exposure exceeding the EPA reference dose, whereas consumption of one tarpon per week did not entail excess exposure. Fortunately, few individuals caught tarpon exclusively. Unlike counterparts in the northeastern United States, they trusted authorities and indicated that they would have heeded warnings of mercury contamination posted where they fished.

Investigations and activities at superfund sites.

Only a small proportion of the hazardous waste sites in the United States have been placed on the National Priority List (NPL), and these have become known as Superfund Sites. Many more sites exist on active industrial or military facilities, and a large number of sites remain to be discovered. It is useful to illustrate several hazardous waste sites to provide a clearer impression of the nature of the hazards, the kind of work done, and the proximity of residences to sites.