PUBLIC HEALTH ASSESSMENT
NAVAL SURFACE WARFARE CENTER
INDIAN HEAD DIVISION (NSWC-IHDIV)
(a/k/a INDIAN HEAD NAVAL SURFACE WARFARE CENTER)
INDIAN HEAD, CHARLES COUNTY, MARYLAND
APPENDIX A: Population and Housing Data; Census Tract Map
Figure 2. Indian Head Naval Surface Warfare Center
TABLE A-1: POPULATION DATA TABLE
| Base* | Town of Indian Head** |
Surrounding Community*** |
|
| Total persons |
971 | 4,346 | 2,918 |
| Total area, square miles |
5.24 | 2.28 | 22.85 |
| Persons per square mile |
185 | 1,908 | 128 |
| % Male |
61.4 | 48.2 | 50.1 |
| % Female | 38.6 | 51.8 | 49.9 |
| % White |
84.3 | 77.5 | 54.7 |
| % Black |
9.9 | 20.0 | 42.9 |
| % American Indian, Eskimo, or Aleut |
1.2 | 1.1 | 1.8 |
| % Asian or Pacific Islander |
2.3 | 1.2 | 0.4 |
| % Other races | 2.3 | 0.2 | 0.2 |
| % Hispanic origin |
6.7 |
0.9 |
0.9 |
| % Under age 10 |
22.3 | 15.4 | 14.9 |
| % Age 65 and older | 0.3 | 12.4 | 9.7 |
Source: Census of Population and Housing, 1990: Summary Tape File 1A (Maryland) [machine-readable data files]. Prepared by the Bureau of the Census. Washington, DC: The Bureau [producer and distributor], 1991.
* Tract 850201
** Tract 850202
*** Tract 8503, Block Groups 1 and 2; and Tract 8504, Block Group 1.
| Base* | Town of Indian Head** |
Surrounding Community*** |
|
| Households |
229 | 1,702 | 918 |
| Persons per household |
3.20 | 2.55 | 3.14 |
| % Households owner-occupied |
20.5 | 75.5 | 80.2 |
| % Households renter-occupied |
79.5 | 24.3 | 19.8 |
| % Households mobile homes |
17.5 | 0.6 | 9.9 |
| % Persons in group quarters |
24.5 | 0.0 | 9.9 |
| Median value, owner-occupied households, $ |
162,500 | 79,700 | 104,800 |
| Median rent paid, renter-occupied households, $ |
535 | 449 | 293 |
* Tract 850201
** Tract 850202
*** Tract 8503, Block Groups 1 and 2; and Tract 8504, Block Group 1
Note: A household is an occupied housing unit, but does not include group quarters such as
military barracks, prisons, and college dormitories.
TABLE A-3: LENGTH OF RESIDENCE IN CURRENT HOUSEHOLD, 1990
|
Town of |
Surrounding | ||
| Total households | |||
| Percentage householders
moving into current housing
unit, by time period
|
67.1 28.6 2.3 0.0 1.9 0.0 |
17.9 33.9 9.8 10.0 13.3 15.0 |
11.3 19.9 15.0 25.7 11.5 16.5 |
Source: 1990 Census of Population and Housing, Summary Tape File 3 (Maryland). U.S. Bureau of the Census, Washington, DC.
* Tract 850201
** Tract 850202
*** Tract 8503, Block Groups 1 and 2; and Tract 8504, Block Group 1
| Base* | Town of Indian Head** |
Surrounding Community*** |
| Persons age 25 and older
% With at least a high school diploma |
|||
| Total households
Median income, $ % Below poverty level |
|||
| Employed persons age 16 and older
(civilian)
% In blue-collar jobs % In white-collar jobs |
|||
| Total housing units
% With water from public system or private company % With water from individual well or other source |
3.1 |
10.1 |
93.8 |
Source: 1990 Census of Population and Housing, Summary Tape File 3 (Maryland). Prepared by Bureau of the Census, Washington, DC.
* Tract 850201
** Tract 850202
*** Tract 8503, Block Groups 1 and 2; and Tract 8504, Block Group 1
APPENDIX B: Summary of Site Evaluations
APPENDIX B: Summary of Site Evaluations, NSWC-IHDIV, Indian Head, Maryland
| Site Location and Number | Evaluation | Comments |
| NSWC: Sites 51, 52 |
There is no evidence of contaminant release(s) at these sites. |
These sites have been removed from the IRP list and designated as "No Further Action" required. |
| NSWC: Sites 5, 8 |
These are sites with surface, sub-surface, shallow groundwater and surface water contamination.
However, based on the information and data currently available for these sites, ATSDR concludes that
there are no public health issues associated with these areas of contamination (other than those
situations identified in the text of the PHA).
|
Removal actions were completed at these sites in 1996. |
| NSWC: Sites 1, 2, 3, 4, 6, 7, 8, 9, 10, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 | These sites are designated for future (unscheduled) Site Screening Activities. | |
| NSWC: Sites 43, 44, 45, 48, 50 | These sites are proposed for future (unscheduled) Remedial Investigation/Feasibility Study activities | |
| NSWC: Sites 11, 12, 39, 42, 43, 46, 47, 49, 53, 54, 55, 56 | These sites are proposed as "high priority" sites for Remedial Investigation /Feasibility Study activities beginning in 1997. | |
| Stump Neck: Sites 30, 31, 32, 33, 34, 35, 36, 37, 38 |
This property has been used primarily for explosives training, mixing, assembly, and disassembly of ordnance, The RCRA Facility Assessment evaluation documents few releases of hazardous substances to the environment. Characterization and clean-up of these sites will proceed under the RCRA Corrective Action Program. |
ATSDR's primary concern with the Stump Neck Annex relates to releases of contaminants to the Mattawoman and Chicamuxen Creeks entering the aquatic food chain. |
ATTACHMENT B
The following section was not available in electronic format for conversion to HTML at the time of preparation of this document. To obtain a hard copy of the document, please contact:
Agency for Toxic Substances and Disease Registry
Division of Health Assessment and Consultation
Attn: Chief, Program Evaluation, Records, and Information Services Branch
E-56
1600 Clifton Road NE, Atlanta, Georgia 30333
| Category | Definition | Criteria |
| A. Urgent public health hazard | This category is used for sites that pose an urgent public health hazard as the result of short-term exposures to hazardous substances. |
|
| B. Public health hazard | This category is used for sites that pose a public health hazard as the result of long-term exposures to hazardous substances. |
|
| C. Potential (indeterminate) public health hazard | This category is used for sites with incomplete information. |
|
| D. No apparent public health hazard | This category is used for sites where human exposure to contaminated media is occurring or has occurred in the past, but the exposure is below a level of health hazard. |
|
| E. No public health hazard | This category is used for sites that do not pose a public health hazard. |
|
| APPENDIX D: | Application, to the NSWC-IHDIV soil data set, of the algorithm relating soil lead concentrations to potential increases in blood lead levels. References are noted in parentheses. |
Application of the Algorithm
The following formula describes the observed relationship between soil lead concentrations
and increases in blood lead (PbB) levels (9):
ln(PbB) = 0.879 + 0.241 ln(Pb soil)
where the PbB data are expressed in units of µg/dL and the concentrations of lead in soil (Pb soil) are expressed as parts per million (ppm) (i.e., µg/g, mg/kg).
If the baseline PbB levels are defined, and the potential increase in PbB levels is calculated using the above formula, the sum of the two values provides an estimate of the predicted total lead concentration in blood if blood lead testing were performed. This value is compared to the CDC public health PbB screening criterion for children of 10 µg/dL to determine if PbB testing of the exposed population is recommended (9):
Testing is not recommended if:
Assumptions:
Baseline blood lead (PbB) levels
Baseline PbB values in exposed communities will vary depending on a number of socio-demographic factors including age, gender, race, income level, and environment (7).
The National Health and Nutrition Examination Survey (NHANES) for 1976 - 1991 provides
baseline PbB data for the U.S. population (11). These data are averaged over age group
categories for children, e.g, 1-2 years, 3-5 years, 6-11 years, etc. Neither baseline PbB data
nor site-specific demographic data were available for the children residing in the NSWC-IHDIV
housing; therefore, for the purposes of these calculations it was assumed that the mean
baseline PbB values at the facility are not significantly different from the national averages for
the overall U.S. population (11). Based on the CDC recommendation for blood lead screening
of children ages 6 years and under (9), we used the NHANES 1-2 year and 3-5 year age group mean values:
| Age | Mean PbB level (µg/dL) |
| 1-2 years 3-5 years |
4.1 3.4 |
Exposure
The calculations assume that the children regularly play in the lead-contaminated soils around
the NSWC-IHDIV housing : this may lead to an overestimate in the potential increase in PbB
levels due to soil exposure. However, the calculations do not integrate the increases in PbB
which may occur due to exposure to other sources of lead in the NSWC-IHDIV residential
setting including inhalation and ingestion of household dusts and ingestion of indoor paint
chips.
Calculations
All NSWC-IHDIV soil lead data values were obtained from the NSWC-IHDIV Housing
Inspection Report (8). The average soil lead concentration was calculated for each unit in each
housing area: samples collected from foundation garden, pedestrian path and play areas were
used. (Data from background and roadside samples were not included in the calculations.) The
housing unit with the highest average soil lead concentration for a particular housing area was
used in the PbB calculations. These calculations are presented below.
Detached Housing
Average foundation soil Pb concentrations ranged from 88.6 (115 Strauss) to 12,669 (7 Pickens) ppm for the NSWC-IHDIV Detached housing units.
For the highest average soil Pb concentration (7 Pickens), the calculated potential increase in PbB is 23.5 µg/dL:
The predicted increase in PbB due to exposure to lead contaminated soils at this average concentration exceeds the screening criterion. Compare the sum of the baseline PbB and increase in PbB to the screening criterion of 10 µg/dL:
La Plata Housing
The highest average lead concentration in soils at the La Plata housing units = 1213.5 ppm
(Unit 6).
For the highest average soil Pb concentration, the calculated potential increase in PbB is 13.3 µg/dL:
Compare the sum of the baseline PbB and increase in PbB to the screening criterion of 10 µg/dL:
For children 5 years of age and under, the predicted PbB levels exceed the screening criterion
of 10 µg/dL.
Waldorf Housing
The highest average lead concentration in soils at the Waldorf housing units = 483 ppm (Unit
2).
For the highest average soil Pb concentration, the calculated potential increase in PbB is 10.7 µg/dL:
Compare the sum of the baseline PbB and increase in PbB to the screening criterion of 10 µg/dL:
For children 5 years of age and under, the predicted PbB levels exceed the screening criterion
of 10 µg/dL.
Riverview Village Apartments
The highest average lead concentration in soils at the Riverview apartments = 91.5 ppm (Unit
16).
For the highest average soil Pb concentration, the calculated potential increase in PbB is 7.1 µg/dL:
Compare the sum of the baseline PbB and increase in PbB to the screening criterion of 10 µg/dL:
For children 5 years of age and under, the predicted PbB levels exceed the screening criterion
of 10 µg/dL.
APPENDIX E: ATSDR Public Health Statement on Mercury
MERCURY
1. PUBLIC HEALTH STATEMENT
This Statement was prepared to give you information about mercury and to emphasize the human health effects that may result from exposure to it. The Environmental Protection Agency (EPA) has identified 1,300 hazardous waste sites as the most serious in the nation. These sites comprise the "National Priorities List" (NPL): Those sites which are targeted for long-term federal cleanup activities. Mercury has been found in at least 600 of the sites on the NPL. However, the number of NPL sites evaluated for mercury is not known. As EPA evaluates more sites, the number of sites at which mercury is found may increase. This information is important because exposure to mercury may cause harmful health effects and because these sites are potential or actual sources of human exposure to mercury.
When a substance is released from a large area, such as an industrial plant, or from a container, such as a drum or bottle, it enters the environment. This release does not always lead to exposure. You can be exposed to a substance only when you come in contact with it. You may be exposed by breathing, eating, or drinking substances containing the substance or by skin contact with it.
If you are exposed to a substance such as mercury, many 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, gender, nutritional
status, family traits, life-style, and state of health.
1.1 WHAT IS MERCURY?
Mercury is a metal (element) that occurs naturally in the environment in several forms. In the metallic or elemental form, mercury is a shiny, silver-white, odorless liquid familiar to anyone who has used a mercury thermometer. Some evaporation of metallic mercury occurs at room temperature to form mercury vapor, a colorless, odorless gas. Some people who have breathed mercury vapors report a metallic taste in their mouth. Mercury can also combine with other elements, such as chlorine, sulfur, or oxygen, to form inorganic mercury compounds or "salts". Most inorganic mercury compounds are white powders or crystals, except for mercuric sulfide (also known as cinnabar) which is red and turns black after exposure to light. In the following text, we include both metallic mercury (liquid and vapor) and inorganic mercury compounds under the generic term "inorganic mercury."
Mercury can also form a chemical bond with carbon to create a large number of organomercurial compounds. It is customary to refer to mercury with bonds to carbon as "organic" mercury. However, only two of these organomercurial compounds (methylmercury and phenylmercury) have been identified at hazardous waste sites. In most instances in the text, we refer to these chemicals by name rather than using the generic term "organic mercury." Like the inorganic mercury compounds, both methylmercury and phenylmercury exist as "salts" (for example methylmercuric chloride or phenylmercuric acetate). When pure, most forms of methylmercury and phenylmercury are white crystalline solids.
Several mercury compounds are found naturally in the environment. The most common forms of mercury naturally found in the environment are metallic mercury, mercuric sulfide, mercuric chloride, and methylmercury. The mercury portion of these forms does not break down into other chemicals. However, the form of mercury found in the environment can be changed slowly by microorganisms and natural processes. Metallic mercury vapor may be changed into inorganic forms, such as mercuric chloride, and inorganic forms may be changed in organic forms of mercury (and vice versa). Methylmercury is the usual organic form of mercury created by these natural processes. It is of particular concern because it can build up in certain fish to levels that are many times greater than in the surrounding water (see Section 1.2)*.
Mercury is mined as mercuric sulfide. Metallic mercury is then refined from the mercuric sulfide by heating the ore above 1000 degrees Fahrenheit and capturing the metallic mercury vapor that is released. There are many different uses for metallic mercury. It is used in the production of chlorine gas and caustic soda. It is also used in thermometers, barometers, batteries, and electrical switches. Silver-colored dental fillings typically contain about 50% metallic mercury. Metallic mercury is also used to extract gold from ore or to reclaim gold from gold-containing articles. Some Mexican-American and Asian populations have used metallic mercury in folk remedies for chronic stomach disorders. Metallic mercury has also been used by Latin-American and Caribbean cultures in occult practices. Inorganic salts of mercury, such as ammoniated mercuric chloride or mercuric iodide, have been used in skin lightening creams. Mercuric chloride has also been used as a topical antiseptic or disinfectant agent. Some chemicals containing mercury, such as mercurochrome and thimerosal, are still commonly used in medicine as antiseptics or as preservatives in eye drops, eye ointments, nasal sprays, and vaccines. Neither mercurochrome or thimerosal have been identified at hazardous waste sites. Mercuric sulfide and mercuric oxide are used as pigments in paints. Mercuric sulfide is also used as a pigment for tattoos. Mercurous chloride was widely used at one time in medicinal products, such as laxatives, worming medications, and teething powders. It has since been replaced by safer and more effective agents. Some inorganic mercury compounds are used in fungicides.
Methylmercury is generally produced by microorganisms in the environment, rather than made
by human activity. However, at one time methyl- and ethylmercury compounds were used to
protect seed grains from fungal infections. This use has been banned since the 1970s.
Phenylmercuric compounds were used as antifungal agents in paints until 1991, when this
use was also stopped. Mercury compounds may be found in the air, soil, and water near
hazardous waste sites. Chapter 3 contains more information on the physical and chemical
properties of mercury. Chapter 4 contains more information on the production and use of
mercury.
1.2 WHAT HAPPENS TO MERCURY WHEN IT ENTERS THE ENVIRONMENT?
Mercury is a naturally occurring metal found throughout the environment as the result of normal breakdown of minerals in the earth's crust by weathering processes involving wind and water. The total amount of mercury entering the environment from natural processes throughout the world is about equal to, or maybe less than, the total amount released by human activities. However, with the exception of mercury ore deposits, the amount of mercury that naturally exists in any one place is usually very low. In contrast, the amount of mercury that may be found at a particular waste site because of human activity can be high. The mercury in air, water, and soil at hazardous waste sites may come from both natural sources and human activity.
Most of the mercury found in the environment is inorganic mercury (metallic mercury and inorganic mercury compounds). This inorganic mercury can enter the air from deposits of ore that contain mercury, from the burning of coal or garbage, and from the emissions of factories that use mercury. Inorganic mercury may also enter water or soil from rocks that contain mercury, factories or water treatment facilities that release water contaminated with mercury, and the disposal of wastes. Inorganic or organic compounds of mercury may be released to the soil through the use of mercury- containing fungicides.
Metallic mercury is a liquid at room temperature. It can evaporate into the air and can be carried long distances before returning to water or soil in rain or snow. As mentioned before, some microorganisms in the water or soil can change inorganic forms of mercury to methylmercury. Methylmercury can enter the water and remain there for a long time, particularly if there are particles in the water to which the methylmercury can attach. If mercury enters the water in any form, it is likely to settle to the bottom where it can remain for a long time. Mercury also remains in soil for a long time. Mercury usually stays on the surface of the sediments or soil and does not move through the soil to underground water.
Small fish and other organisms living in the water can take up methylmercury and inorganic
forms of mercury. When larger fish eat small fish or other organisms that contain
methylmercury, most of the methylmercury originally present in the small fish will be stored in
the bodies of the large fish. As a result, large fish living in contaminated waters can collect a
relatively large amount of methylmercury. Plants may have a greater concentration of
inorganic mercury in them if they are grown in soil that contains higher than normal amounts
of mercury. For further information on what happens to mercury in the environment, refer to
Chapters 4 and 5.
1.3 HOW MIGHT I BE EXPOSED TO MERCURY?
Because mercury occurs naturally in the environment, everyone is exposed to very low levels of mercury in air, water, and food. However, some people may be exposed to higher levels of mercury. One of the most likely ways that the general population will be exposed to higher levels of mercury is through eating fish or shellfish contaminated with methylmercury. Some fish contain such high levels of methylmercury that selling them for human consumption has been prohibited. In addition, public health advisories have been issued by state and federal authorities to discourage anyone from catching fish from some areas for human consumption. Other foods typically contain very little methylmercury or other forms of mercury. The other most likely form of exposure is by absorbing mercury vapors released from dental fillings. Most silver-colored dental fillings are about 50% metallic mercury and slowly release small amounts of mercury vapor.
Sources of higher exposure to mercury include breathing air containing mercury vapors released from metallic mercury spills, incinerators, and facilities that burn mercury-containing fuels (for example, coal or other fossil fuels). Exposure near hazardous waste sites is likely to occur by breathing contaminated air, having contact with contaminated soil, or drinking contaminated water. Persons may be exposed to mercury compounds in medicinal products, such as antiseptics or skin lightening creams, that contain small amounts of mercury.
In the past, the level of mercury found in outdoor air has been reported to be between 10 and 20 nanograms of mercury per cubic meter (ng/m3) of air in urban areas. Background or natural levels are generally about 6 ng/m3 or less. Mercury levels found in surface water are generally less than 5 ng per liter of water. Levels normally found in soil range from 20 to 625 ng of mercury per gram of soil. The Food and Drug Administration (FDA) has estimated that, on average, most people are exposed to about 50 ng of mercury per kilogram of body weight per day in the food they eat. This amount translates to about 3.5 micrograms (mg) of mercury per day for an adult of average weight. A large proportion of this mercury, in the form of methylmercury, is likely to come from fish. Furthermore, people who eat a lot of fish are likely to have higher exposure to methylmercury. Mothers with mercury in their blood can expose their unborn children to methylmercury. Infants who nurse can be exposed to methylmercury and inorganic mercury in their mother's milk.
Workers in some occupations may also be exposed to inorganic mercury (metallic and inorganic mercury compounds) in the workplace. Most exposures on the job occur as a result of breathing air that contains mercury vapors. Exposure occurs in the medical, dental, and other health services, and in the chemical, metal processing, electrical equipment, automotive, building, and other industries. Families of workers may be exposed to mercury in the home if the workers' clothes have been contaminated with mercury. Dentists and their assistants may also be exposed to metallic mercury from skin contact with materials used to fill cavities in the teeth and breathing metallic mercury vapor released from these materials.
Exposure to mercury can be determined by measuring amounts in blood, urine, and hair.
Levels found in blood, urine, or hair may show whether health effects are expected (see
Section 2.5). Refer to Chapter 5 for more information on how you might be exposed to
mercury.
1.4 HOW CAN MERCURY ENTER AND LEAVE MY BODY?
Mercury can easily enter your body when you breathe in air containing metallic mercury vapor. Most of the mercury vapor you breathe in enters your bloodstream and goes rapidly to other parts of the body. Inhaled metallic mercury can reach the fetuses of pregnant women easily. Some metallic mercury can be changed by your body into mercuric chloride. Some mercury that enters your bloodstream as metallic mercury may stay in your body for weeks or months. It stays mostly in the kidney and brain, as either metallic mercury or mercuric chloride. Metallic mercury that you breathe in will leave your body in the urine, feces, and breath. Metallic mercury that you might swallow in the liquid form does not enter the bloodstream very easily, and most of it leaves the body in the feces.
Inorganic salts of mercury (mercurous chloride or mercuric chloride, for example) that are inhaled are not believed to enter your body as easily as inhaled metallic mercury vapor. However, these inorganic forms of mercury, if swallowed, enter the body more easily than metallic mercury. Inorganic mercury can also enter the bloodstream directly through the skin. However, only a small amount would pass through your skin compared with breathing or swallowing inorganic mercury. After entering the body, inorganic compounds of mercury can also reach many tissues. Mercurous mercury in your body breaks down to metallic mercury and mercuric mercury. Some mercuric mercury may stay in your body, mostly in the kidneys. Mercuric salts of mercury cannot reach the brain as easily as metallic mercury. Inorganic mercury leaves your body in the urine or feces over a period of several weeks or months.
Some organic compounds of mercury (such as methylmercury) can evaporate slowly at room
temperature and can enter your body easily as vapors through the lungs. Methylmercury in
contaminated fish or other foods that you might eat enters your bloodstream easily and goes
rapidly to other parts of your body. It can also enter the bloodstream directly through the skin,
but only in small amounts. Organic mercury compounds (such as methylmercury) that are in
the bloodstream are similar to metallic mercury because they can reach most tissues including
the brain and fetus. Methylmercury can change to inorganic mercury in the brain and remain
there for a long time. Methylmercury that you swallow or breathe leaves your body in the
feces, mostly as inorganic mercury. It leaves the body over a period of several months For
more information on how mercury can enter and leave your body, please refer to Chapter 2.
1.5 HOW CAN MERCURY AFFECT MY HEALTH?
Exposure to high enough levels of metallic, inorganic, or organic mercury can permanently damage the brain, kidneys, and developing fetus. The nervous system is very sensitive to mercury's effects. The changes that mercury causes in the brain are not specific for one type of brain function. Therefore, a variety of effects may occur. These effects include personality changes (irritability, shyness, nervousness), tremors, changes in vision or hearing, and difficulties with memory. Because of differences in the way that different forms of mercury are able to travel through the body, not all forms of mercury are equally able to affect the nervous system. For example, breathing in large amounts of metallic mercury vapors and breathing in or swallowing large amounts of methylmercury are more likely to cause nervous system effects than swallowing large amounts of inorganic mercury salts. This difference is because mercury transport into the brain is very low after exposure to inorganic salts of mercury, such as mercuric chloride. Therefore, exposure to this form of mercury is less likely to cause nervous system toxicity. The extent of recovery depends on what kind of nervous system damage mercury caused.
The kidney is also very sensitive to mercury. All forms of mercury are able to cause kidney damage if large enough amounts enter the body. Recovery from the kidney effects of mercury is likely, once the body clears itself of the contamination, if the damage caused by the mercury is not too great.
In addition to the effects described above, short-term exposure to high levels of metallic mercury vapor in the air can damage the lungs, cause nausea, vomiting, or diarrhea, cause increases in blood pressure or heart rate, and cause skin rashes or eye irritation. Long-term exposure of workers in several industries to metallic mercury has been shown to cause similar effects. Levels of metallic mercury in air were greater than the levels normally encountered by the general population. Current levels of mercury in workplace air are lower than in the past. Because of this reduction, fewer workers are expected to have symptoms from mercury exposure. Results of studies in humans showed that there were no effects on the ability to have children after breathing metallic mercury for a long time. Studies in workers exposed to metallic mercury vapors have not shown an increase in cancer. Skin contact with the metal mercury causes allergic reactions (skin rashes) in some people.
Other than effects on the kidneys, little is known about the effects of inorganic mercury salts on the body. Some people have shown nausea and diarrhea after swallowing large amounts of inorganic mercury salts, and some have shown nervous system effects. There is no information on long-term, low-level exposures in humans.
People who have eaten fish containing large amounts of methylmercury or seed grains treated with methylmercury or other organic mercury compounds have had permanent damage to the brain, kidneys, and the growing fetus. The amounts of organic mercury that cause these effects are higher than the amounts to which the general population is exposed daily. Exposure to methylmercury may cause brain damage in the developing fetus. Exposure to methylmercury is also likely to be more dangerous for young children than for adults. This is because relatively more methylmercury passes into the brains of young children than adults, and because methylmercury interferes with brain development.
Studies in animals show similar effects to those seen in people. Studies in animals have also provided more information on types of exposure for which human data are limited. For example, studies in animals provide information about the effects of long-term exposure to mercury through food, water, or inhaled dust. These studies show that long-term oral exposure to inorganic mercury salts can cause kidney damage, effects on blood pressure and heart rate, and effects on the stomach. Studies in animals also provide important information about an autoimmune reaction that may occur in sensitive populations after swallowing inorganic mercury salts. Some studies in animals also show that nervous system damage occurs after long-term exposure to high levels of inorganic mercury. Short- term high level exposure to inorganic mercury affects the fetus in animals. The general population is generally not exposed to levels high enough to produce these effects.
In addition to the effects observed in people who have eaten food contaminated with methylmercury, studies in animals exposed to methylmercury or phenylmercury show that long-term exposure to high levels can cause kidney damage, damage to the stomach and large intestine, changes in blood pressure and heart rate, adverse effects on the developing fetus, sperm, and male reproductive organs, and increases in the number of spontaneous abortions and stillbirths. Adverse effects on the nervous system of animals occurred at lower doses than most other effects. This difference indicates that the nervous system is more sensitive to methylmercury toxicity than other organs in the body.
Studies also show that animals given inorganic mercury salts by mouth for most of their
lifetime had increases in some kinds of tumors. Animals that received methylmercury or
phenylmercury in their drinking water or feed for most of their lives had increases in cancer of
the kidney. There is no information to show that mercury causes cancer in humans. The
Department of Health and Human Services (DHHS), EPA, and the International Agency for
Research on Cancer (IARC) have not classified mercury as to its human carcinogenicity.
Chapter 2 contains information on health effects of mercury in humans and animals.
1.6 IS THERE A MEDICAL TEST TO DETERMINE WHETHER I HAVE BEEN EXPOSED TO MERCURY?
There are reliable, accurate, and easily available ways to measure mercury levels in the body. However, the most easily available tests do not determine the form of mercury to which you might have been exposed. Blood or urine samples can be taken in a doctor's office and tested using special equipment in a laboratory. Mercury in urine is used to test for exposure to metallic mercury vapor and to inorganic forms of mercury. Blood levels are measured less frequently. Measurement of mercury in whole blood or scalp hair is also used to monitor exposure to methylmercury. Urine is not useful for testing whether exposure has occurred to methylmercury. Levels found in blood, urine, and hair may be used to predict possible health effects that may be caused by the different forms of mercury.
Levels of mercury found in the urine provide information about recent exposures better than
about long-term exposures. Blood and urine levels are useful during and after short- and
long-term exposures. However, several months after exposure ends, mercury levels in the
blood and urine are much lower. Hair can be used to show exposures that occurred many
months ago, or even more than a year ago if the hair is long enough and careful testing
methods are used. These methods for hair analysis are not easily available. Short-term
exposure to mercury can also be evaluated by measuring mercury in the breath, but only
within a few days after exposure. For more information on testing for mercury levels in the
body, see Chapters 2 and 6.
1.7 WHAT RECOMMENDATIONS HAS THE FEDERAL GOVERNMENT MADE TO PROTECT HUMAN HEALTH?
The government has developed regulations and guidelines for mercury. EPA has established many regulations to control air pollution. These are designed to protect the public from the possible harmful health effects of mercury.
EPA and the FDA have set a limit of 2 parts mercury per billion (ppb) parts of water in drinking water. EPA also recommends that the level of inorganic mercury in rivers, lakes, and streams should be no more than 144 parts mercury per trillion (ppt) parts of water to protect human health (1 ppt is a thousand times less than 1 ppb). EPA suggests that a daily exposure to 2 ppb of mercury in drinking water for an adult of average weight is not likely to cause any significant adverse health effects. The FDA has set a maximum permissible level of 1 part of methylmercury in a million parts (ppm) of seafood products (1 ppm is a thousand times more than 1 ppb). The FDA also may seize treated seed grain containing more than 1 ppm of mercury.
The Occupational Safety and Health Administration (OSHA) regulates levels in the workplace. It has set a limit of 0.01 mg/m3 for organic mercury and 0.05 mg/m3 for metallic mercury vapor in the workplace air to protect workers during an %-hour shift and a 40-hour work week. The National Institute for Occupational Safety and Health (NIOSH) recommends that the amount of metallic mercury vapor in workplace air be limited to 0.05 mg/m3 averaged over a 10-hour work shift.
1.8 WHERE CAN I GET MORE INFORMATION?
If you have any more questions or concerns, please contact your community or state health or environmental quality department or:
This agency can also provide you with information on the location of occupational and environmental health clinics. These clinics specialize in the recognition, evaluation, and treatment of illness resulting from exposure to hazardous substances.
*Note: This Public Health Statement on mercury is derived from the ATSDR Toxicological Profile for Mercury (Reference 17). Section and chapter references in the public health statement are contained in the toxicological profile.
