The database compiled by the Riso National Laboratory is the most comprehensive record of yearly fallout (column 1 of the following table) and cumulative fallout (column 2) for radiocesium available in the public domain. The Riso Laboratory has also compiled an equally comprehensive record of ⁹⁰Sr which is not cited in this website. The U.S. also collected detailed data about the dietary intake of fallout nuclides, cited in Section 9, but most unclassified U.S. environmental monitoring reports consist of summaries of composites, usually monthly or quarterly averages, which successfully mask real time localized pulses of radiation, especially in areas close to the weapons testing site in Nevada. The research and publications of the Riso National Laboratory set the standard for media specific analysis of environmental radiation which remained unchallenged until the Chernobyl accident, at which time Finland compiled the most comprehensive reports of the impact of the accident.

Denmark was considered to have received a minimal amount of Chernobyl derived radiocesium and other radionuclides. The mean deposition of 1,210 Bq/m² recorded in Denmark in 1986 was, nonetheless, higher than the highest annual cesium deposition during any preceding year but still insignificant compared to the peak depositions of 60,000 to 100,000 Bq/m² recorded in sections of Norway, Sweden, Finland and England. These countries are among the few locations which have maintained adequate record keeping of the impact of the Chernobyl accident; the tradition of freedom of information (FOI) pertaining to radioactivity in the environment needs to be expanded to include a comprehensive survey of the areas adjacent to fuel reprocessing, weapons production, and nuclear power production facilities. There is an urgent need for comprehensive radiological surveys, including radiometric surveys of contamination deposition expressed as radioactivity per square meter, media specific pathway analyses for the population groups most impacted by anthropogenic source points of radioactive contamination, and real-time nuclide specific monitoring of air concentrations of radioactive effluents. The research and record keeping of the Riso National Laboratory pertaining to the accumulated fallout from weapons tests, as well as its comprehensive media specific yearly reports represent the first step in updating antiquated radiological surveillance paradigms.
 

Fallout rates and accumulated fallout (Bq ¹³⁷Cs m-2) in Denmark 1950-1991 (1)

	Denmark		Jutland		Islands
Year	di	Ai(30.02)	di	Ai(30.02)	di	Ai(30.02)
1950	1.243	1.215	1.302	1.273	1.184	1.157
1951	5.979	7.030	6.749	7.838	5.210	6.221
1952	11.722	18.323	13.261	20.618	10.182	16.029
1953	29.600	46.830	33.507	52.889	25.693	40.770
1954	112.539	155.731	127.398	176.173	97.680	135.290
1955	148.059	296.857	167.595	335.922	128.523	257.792
1956	183.579	469.471	207.792	531.304	159.366	407.637
1957	183.579	638.145	207.792	722.227	159.366	554.062
1958	254.678	872.445	288.245	987.409	221.053	757.424
1959	361.238	1205.526	408.954	1364.492	313.582	1046.561
1960	67.488	1243.959	76.427	1408.032	58.608	1079.940
1961	87.675	1301.241	99.219	1472.849	76.072	1129.632
1962	439.738	1701.242	472.179	1900.635	407.296	1501.849
1963	988.344	2628.199	1092.418	2924.739	884.270	1331.659
1964	616.390	3170.535	691.752	3533.949	541.029	2807.121
1965	234.077	3326.905	248.877	3696.486	219.277	2957.324
1966	126.984	3375.057	128.227	3737.418	125.741	3012.697
1967	61.982	3358.593	69.619	3720.145	54.346	2997.040
1968	83.058	3363.098	92.826	3725.944	73.230	3000.195
1969	61.272	3346.212	73.467	3712.693	49.077	2979.675
1970	97.502	3365.115	117.986	3743.247	77.019	2986.928
1971	89.155	3375.430	102.179	3757.659	76.131	2993.148
1972	25.752	3323.554	27.054	3698.331	24.450	2948.724
1973	11.366	3258.804	12.728	3626.358	9.946	2891.141
1974	42.032	3225.498	46.117	3588.654	38.066	2862.350
1975	24.509	3175.828	26.758	3532.894	22.259	2818.771
1976	6.098	3109.302	6.867	3458.970	5.328	2759.642
1977	22.733	3060.549	23.976	3403.451	21.430	2717.597
1978	27.410	3017.479	31.850	3356.893	22.970	2678.016
1979	9.827	2958.211	10.301	3290.341	9.235	2625.917
1980	5.606	2896.171	6.766	3221.854	4.591	2570.470
1981	17.059	2846.738	18.316	3166.216	15.948	2527.385
1982	2.706	2784.409	2.851	3096.736	2.561	2472.203
1983	2.151	2722.959	2.126	3028.134	2.175	2417.902
1984	1.751	2662.521	1.935	2960.911	1.567	2364.247
1985	1.290	2603.012	1.191	2894.495	1.388	2311.642
1986	1210.000	3725.984	1340.000	4137.847	1080.000	3314.232
1987	29.000	3669.280	32.000	4074.674	26.000	3263.994
1988	11.900	3597.161	13.400	3994.768	10.300	3199.562
1989	3.500	3518.480	4.510	3907.998	2.530	3129.007
1990	2.63	3440.744	3.85	3822.564	1.41	3058.968
1991	1.63	3363.805	1.92	3737.194	1.36	2990.480

(1) Aarkrog, A., Botter-Jensen, L., Jiang, Chen Quing, Dahlgaard, H., Hansen, H., Holm, E., Lauridsen, B., Nielsen, S.P., Strandberg, M. and Sogaard-Hansen, J. (1992). Environmental radioactivity in Denmark in 1990 and 1991. Roskilde, Denmark: Riso National Laboratory.
 

4. Cesium Baseline (to 1986)

Cesium-137 is the nuclide of choice in this website for the documentation of both stratospheric fallout contamination and Chernobyl derived fallout (See Section 10). Strontium-90 is the nuclide most associated with weapons fallout, and it occurred in larger quantities in stratospheric fallout than radiocesium. However, radiocesium is the largest constituent of spent fuel, the most prevalent long-lived component of the tropospheric plume which originated at Chernobyl, and an omnipresent fission product resulting from most nuclear industries and activities.

• Most of the following baseline data are pre-Chernobyl peak concentrations unless otherwise noted.
• Data is compiled from dry weight samples unless noted as wet weight, except milk.
• Baseline data is listed in order of the date of the research, beginning with data collected in the early days of nuclear testing.

Booker, D.V. (1959). Cesium-137 in dried milk. Nature,183. pg. 921-924.
 

1957

England

Milk

137Cs

870 pCi/kg

• Data collected near the Windscale accident.

• The impact from stratospheric fallout increased the daily intake of radiocesium well above the previous August 1960 average of 22 pCi/day. 40% of the dietary intake of radiocesium in Japan comes from polished rice.

Wilson, A. R. and Spiers, F.W. (1967). Fallout cesium-137 and potassium in new-born infants. Nature, 215, 470-474.
 

1966	Leeds, England	Mother	137Cs	0.202 nc/kg (202 pCi/kg)
1966	Leeds, England	Infant	137Cs	0.196 nc/kg (196 pCi/kg)

• "the biological half life for ¹³⁷Cs in an adult averages about 100 days for the principal component, comprising about 90 percent of the intake by ingestion. In infants the biological half life is 5 to 10 times lower." (p. 470).

• Reflects stratospheric fallout from weapons testing.

Brisbin, I.L., Geiger, R.A. and Smith, M.H. (1973). Accumulation and redistribution of radiocaesium by migratory waterfowl inhabiting a reactor cooling reservoir. Environmental Behavior of Radionuclides Released in the Nuclear Industry, Vienna: International Atomic Energy Agency.
 

1971-72

Savannah River, S.C.

(Waterfowl) Common Gallinules

137Cs

1,500 pCi/kg live weight

• This is a highly contaminated ecosystem. See Section 11 for additional information on the Savannah River source point.

Hawthorne, H.A., Zellmer, S.D., Eberhard, L.L. and Thomas, J.M. (1976). 137 Cesium cycling in a Utah dairy farm. Health Physics, 30, 447- 464.
 

1963-67

Utah Dairy Farm

Alfalfa

137Cs

3,058 pCi/kg (112.4 Bq/kg)

• Peak value of ¹³⁷Cs in fallout collectors (funnels): 145.4 Bq/m²; reflects contamination from local nuclear weapons tests.

• ¹³⁷Cs concentrations in watershed soils ranged from 56-149 nCi/m² (2,080 - 5,520 Bq/m²) with peak values in reservoir sediments up to 1,280 nCi/m² and a mean value of 676 nCi/m² for cultivated watersheds. Both the cultivated soil and the reservoir sediments serve as a sink or a trap for cesium being washed out of the watershed soils.

• Record keeping of air concentrations for ¹³⁷Cs begin in 1963 and end in 1979; peak concentrations are noted as 149 femtocuries/m³ in April of 1963 at Miami, Florida, and gradually drop to 10 femtocuries/m³ or less in the spring of 1966; no data is available between May, 1966, and June, 1968, after which time low concentrations of ¹³⁷Cs are consistently observed until November of 1979. Most concentrations in this latter time frame are less than 5 femtocuries/m³ and in many cases are below 1 femtocurie/m³.
• EML publications contain surprisingly little data about cumulative ground deposition of the most significant weapons testing derived radionuclides and almost no data whatsoever pertaining to media specific concentrations of these nuclides in the biotic environment. A comparison of the EML publications and the EPA's Environmental Radiation Data Reports with the publications of the Riso National Laboratory graphically illustrate that, while the United States is in the vanguard of creating radioactive contamination from anthropogenic source points, it is still in the late Stone Age when it comes to monitoring these effluents.

National Research Council of Canada. (1983). Radioactivity in the Canadian aquatic environment. NRCC Report no. 19250.

Holm, E., Persson, B.R.R., Hallstadius, L., Aarkrog, A. and Dahlgaard, H. (1983). Radiocesium and transuranium elements in the Greenland and Barents Seas. Oceanol. Acta., 6, 4, 457-462.
 

June-Oct. 1980	Barents Sea	Sediment	137Cs	18.1 Bq/kg
June-Oct. 1980	Barents Sea	Sediment	239Pu	1.10 Bq/kg

Davis, R.B., Hess, T.C., Norton, S.A., Hanson, D.W., Hoagland, K.D. and Anderson, D.S. (1984). ¹³⁷Cs and ²¹⁰Pb dating of sediments from soft-water lakes in New England (U.S.A.) and Scandinavia, a failure of ¹³⁷Cs dating. Chemical Geology, 44, 151-185.
 

1978	Norway / pond	Sediment	137Cs	39,900 pCi/kg
1979	Maine / pond	Sediment	137Cs	21,400 pCi/kg
1979	Norway / pond	Sediment	137Cs	32,100 pCi/kg

• Natural processes also mixed ¹³⁷Cs with prefallout sediments.

Casso, S.A. and Livingston, H.D. (1984). Radiocesium and other nuclides in the Norwegian-Greenland seas (Woods Hole Oceanographic Institute Technical Report WHOI-84- 40). Woods Hole, MA: Woods Hole Oceanographic Institute.
 

1981

Norwegian Sea

Seawater

137Cs

570 d.p.m./100 kg

• Median values were less than 100 d.p.m./100 kg with the greatest concentration ratios of radiocesium near or at the ocean surface.

Finnish Centre for Radiation and Nuclear Safety. (1986). Studies on environmental radioactivity in Finland in 1986: Annual Report. Report No. STUK-A55. Finnish Centre for Radiation and Nuclear Safety, Helsinki, Finland.
 

Dec.-April 1986	Finland	Air concentration	131I	4.3 µBq/m3
Dec.-April 1986	Finland	Air concentration	134Cs	0.25 µBq/m3
Dec.-April 1986	Finland	Air concentration	137Cs	1.25 µBq/m3
Dec.-April 1986	Finland	Milk	137Cs	0.23 Bq/l
Dec.-April 1986	Finland	Beef	137Cs	0.9 Bq/kg
1980-1985	Finland	Pike	137Cs	42 Bq/kg mean concentration

• This report contains detailed information on pre-Chernobyl dietary intake of radiocesium in many media as well as extensive data on the body burdens of radiocesium in reindeer herders and fisherfolk.
• The air concentrations listed above are very significant for two reasons: they give expression to the very sophisticated radiological surveillance technology in place in Finland prior to the Chernobyl accident whereby very small amounts of air concentrations of radioactive contamination can be measured by air sampling equipment which is far superior in its sensitivity to any equipment in the United States available a decade later. The antiquated equipment still in use in the United States has a limit of detection (LOD) two orders of magnitude higher than the Finnish air filters which routinely measure air contamination in millionths of a becquerel per cubic meter of air.
• During the passage of the Chernobyl accident plume, air concentrations of dozens of volatile and/or vaporized radionuclides reached the millions, tens of millions and hundreds of millions of µBq/m³, not only in Finland, but in far-field locations such as Canada (See RAD 10, Canada).
• These seemingly insignificant pre-Chernobyl air concentrations provide an important baseline for evaluating the significance of the Chernobyl plume which would soon pass over Finland.

Scottish Development Department. (1987). Statistical Bulletin, Number 1(E), 1987. Edinburgh: Government Statistical Service.

• Annual mean concentrations of cesium-137 in milk 1981-1985: all readings at or below 0.2 Bq/l.
• Annual mean concentrations of cesium-137 in salmon 1981 2.6 (Bq/kg wet weight); 1982 4.1; 1983 1.3; 1984 1.5; 1985 3.1.
• This publication contains extremely detailed data about pre-Chernobyl activity levels in many media; much of the data was collected in the vicinity of Scottish nuclear power stations, naval installations, and other source points of radioactivity and constitutes a comprehensive baseline of environmental radioactivity levels prior to the Chernobyl accident. This report does not differentiate activity from weapons test fallout from local source point activity; at this point in time, background artificial radiation levels have many origins.

Cunningham, J.D., O'Grady, J. and Rush, T. (1988). Radioactivity monitoring of the Irish marine environment, 1985-86. Nuclear Energy Board, Dublin.
 

1985-86	Irish Sea	Seaweed	137Cs	0.5 Bq/kg pre-Chernobyl mean
1985	Irish Sea	Whiting (fish)	137Cs	pv 91 Bq/kg pre-Chernobyl

• Reflects Sellafield contamination. Mean values of all fish and shellfish 1985: 8.4 - 35.2 Bq/kg.

• These pond "B" peak values are 26 times higher than the relatively uncontaminated north arm of the nearby Par Pond. See Section 11 for additional information on the Savannah River plume source point.