Silver health effects

Silver compounds having anions that are inherently toxic, eg, silver arsenate and silver cyanide, can cause adverse health effects. The reported rat oral LD values for silver nitrate, silver arsenate [13510-44-6] and silver cyanide are 500—800 (29), 200—400 (29), and 123 mg/kg (30), respectively. Silver compounds or complexes ia which the silver ion is not biologically available, eg, silver sulfide and silver thiosulfate complexes, are considered to be without adverse health effects and essentially nontoxic. 

In 1980, the EPA pubHshed ambient water quaHty criteria for silver. An upper limit of 50 f-lg/L in natural waters was set to provide adequate protection against adverse health effects (38). In 1992, EPA deleted the human health criteria for silver from the ambient water quaHty criteria to be consistent with the drinking water standards (39). 

Levels of significant Exposure to Silver - Oral 2-2 Existing Information on Health Effects of Silver 5-1 Frequency of Sites with Silver Contamination... 

Human Health Effects from Breathing Silver ... 

Animal Health Effects from Eating or Drinking Silver... 

This Statement was prepared to give you information about silver and to emphasize the human health effects that may result from exposure to it. The Environmental Protection Agency (EPA) has identified 1177 sites on its National Priorities List (NPL). Silver has been found at 27 of these sites. However, we do not know how many of the 1177 NPL sites have been evaluated for silver. As EPA evaluates more sites, the number of sites at which silver is found may change. The information is important for you because silver may cause harmful health effects and because these sites are potential or actual sources of human exposure to silver. 

If you are exposed to a hazardous substance such as silver, several factors will determine whether harmful health effects will occur and what the type and severity of those health effects will be. These factors include the dose (how much), the duration (how long), the route or pathway by which you are exposed (breathing, eating, drinking, or skin contact), the other chemicals to which you are exposed, and your individual characteristics such as age, sex, nutritional status, family traits, life style, and state of health. 

Studies of the health effects of silver in animals commonly use silver nitrate. Doctors and scientists assume that effects seen using silver nitrate in animals will be very similar to effects in humans caused by any silver compound. While this is likely to be true, it is still possible that some silver compounds will be more harmful, or toxic, than silver nitrate. 

Silver does have helpful uses. For example, silver nitrate was used for many years as drops in newborns eyes to prevent blindness caused by gonorrhea, and is also used in salves for burn victims. Some water treatment methods (including water filters) also use a form of silver to kill bacteria. More information on the health effects from exposure to silver is presented in Chapter 2. More information on the helpful uses of silver is presented in Chapter 4. 

Tables 1-1 through 1-4 present the information that is available concerning specific levels of exposure and health effects. The amount of silver that has caused death in rats, and that has caused mice to be less active are shown in Table 1-4.

There are reliable and accurate ways of measuring silver in the body. Silver can be measured in the blood, urine, feces, and body tissues of exposed individuals. Because urine and blood samples are easy to get, these fluids are most often used to find out if a person has been exposed to silver in the last week or so. Silver builds up in the body, and the best way to learn if past exposure has occurred is to look for silver in samples of skin. Tests for silver are not commonly done at a doctor s office because they require special equipment. Although doctors can find out if a person has been exposed to silver by having blood or skin samples examined, they can not tell whether any health effects will occur. Information about tests for measuring silver in the body is in Chapters 2 and 6. 

No studies were located regarding the following health effects in humans or animals after inhalation exposure to silver or silver compounds. 

Section 104(i)(5) of CERCLA, directs the Administrator of ATSDR (in consultation with the Administrator of EPA and agencies and programs of the Public Health Service) to assess whether adequate information on the health effects of silver is available. Where adequate information is not available, ATSDR, in conjunction with the National Toxicology Program (NTP), is required to assure the initiation of a program of research designed to determine the health effects (and techniques for developing methods to determine such health effects) of silver. 

The majority of literature reviewed concerning the health effects of silver in humans described case reports of individuals who developed argyria following oral exposure to silver. Occupational studies describing two separate worker populations were also located. The predominant route of exposure in the occupational studies is believed to have been inhalation, but the possibility of some degree of oral or dermal exposure cannot be ruled out. Information on human exposure is limited in that the possibility of concurrent exposure to other toxic substances cannot be excluded, and the duration and level of exposure to silver generally cannot be quantitated from the information presented in these reports. 

FIGURE 2-2. Existing Information on Health Effects of Silver... 

No on-going studies were identified that explore the health effects or toxicokinetics of silver or that attempt to associate silver levels in human tissues with effects. 

Highly sensitive methods exist to measure silver concentrations in blood, urine, hair, and skin samples of individuals showing the few health effects that have been associated with silver exposure. These methods are also able to accurately measure background levels in the population. No additional analytical methods appear to be needed for the known biomarkers of effect. 

Sophisticated and highly refined methods are available to detect trace levels of silver and its compounds in air, solid waste leachate, water (the medium of most concern for human exposure), food, and other environmental media. These methods can accurately measure background levels in environmental samples, as well as levels at which health effects occur. There are no known deficiencies in the analytical methods for determining silver in environmental media, and no additional analytical methods appear to be necessary. 

Drake, P. L., and Hazelwood, K. 1. 2005. Exposure-related health effects of silver and silver compounds A review. Annals of Occupational Hygiene. 

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