Radionuclides in Italian Drinking Water and Regulations: Data Collection to Improve Risk Assessment

Abstract

Drinking water, in addition to the best-known chemical and biological agents, contains radionuclides of both natural and artificial origin, which can contribute significantly to the overall effective dose received by the population. The Italian Decree Law 28/2016, implementing the 2013/51/EURATOM Directive, establishes the activities for risk management and the parameter values for different radionuclide activity concentrations. In addition to the institutions involved, the National Inspectorate for Nuclear Safety and Radiation Protection (ISIN) annually publishes monitoring reports of environmental radioactivity in Italy, including radioactivity in drinking water. The purpose of the study was to integrate ISIN reports with 2018–2020 data by collecting measurements performed by institutional laboratories to obtain more complete information and adding, for the Campania region, some data not yet published. This new updated report was not significantly different from ISIN’s one, meaning that those publications are nevertheless extremely representative of the radioactivity in Italian drinking water. However, the study allowed us to obtain more detailed data, including measurements not considered in ISIN reports, for instance, radon-222 activity concentrations. This may be of great usefulness for all radiation protection stakeholders in order to ensure environmental protection, pollution prevention, and population safety.

1. Introduction

Radionuclides can be found in air, water, soil, and living organisms as a consequence of natural and artificial contamination [1]. However, sources of natural origin mostly contribute to environmental radioactivity. In particular, radioisotopes in soil and rocks are those from uranium-238 (U-238) and thorium-232 (Th-232) chains, and potassium-40 (K-40). These nuclides, together with any artificial radionuclides due to accidental contamination [2], are also released into groundwater through erosion and dissolution processes [3,4]. Given the great heterogeneity of radionuclides in drinking water, radiological risk management is done by performing measurements of gross alpha and gross beta activity concentrations [5,6,7,8]. Moreover, particular attention is also given to the activity concentrations of radon (Rn-222) and tritium (H-3) [9].

The impact on human health is due to stochastic events peculiar to carcinogenic substances; therefore, there is no dose-response relationship, but the onset of the effect can occur for any dose, with severity not dependent on the dose and being random in the exposed population. However, as the dose increases, the probability of the effect occurring increases, and the latency period can also be very long. For this reason, the International Commission on Radiological Protection (ICRP) recommends adopting a linear no-treshold-LNT model [10]. Paying particular attention to the radiometric characterization of drinking water, even the measurement and monitoring of radionuclides required by law have a biological impact, particularly concerning the internal exposure of the representative individual.

Rn-222, originating from the U-238 series, is dissolved in water given its physio-chemical characteristics [11]. The biological hazard associated with radon exposure is related to inhalation and ingestion since the alpha particles generated by the decay of radon and its daughters can damage the cells of the bronchioles and intestinal tract [12,13,14,15,16]. Despite these two different internal exposure scenarios, it has been concluded that the most important mechanism of exposure to Rn-222 in drinking water is inhalation [17] because of the propriety of the gas to exhale from the water itself. H-3 is a radioisotope of hydrogen with a mainly cosmogenic origin formed in the high atmosphere that reaches the ground with rain [18,19]. A small fraction is H-3 of artificial origin, produced by human activities such as research and nuclear power plants. Even if its radiotoxicity is low compared to other radionuclides, there is an interest in the biological consequences of low-dose H-3 exposures since it can occur in three different forms: tritium water, tritium gas, and bounded organic molecules, each with a different contribution to tissue irradiation because of different distribution modes inside the organism [20,21]. However, given the few data available in literature regarding the risk correlated with tritium exposure, it is hard to assess the related biological effects [22,23].

In this complex framework, it appears essential to regulate and monitor radioactivity in drinking water in order to ensure radiological safety. Despite the origin of radioactivity, the intake of radionuclides by drinking water is considered a planned exposure situation rather than a source of environmental background radiation [24,25]. Globally, the World Health Organization (WHO) [26] and the International Commission on Radiological Protection (ICRP) [10] advise an Individual Dose Criterion (IDC) of 0.1 mSv/year as an effective dose limit, a value considered sufficiently low to pose minimal risk and not lead to any detrimental health consequences compared to the total exposure to environmental radioactivity. In order not to exceed the IDC of 0.1 mSv/year, the WHO recommends screening levels of 0.5 Bq/L and 1 Bq/L for gross alpha and beta activities, respectively [27]. If the gross beta activity is higher than 1 Bq/L, the K-40′s contribution is evaluated, and the residual beta activity is calculated by subtraction. The result of this additional assessment might indicate that no action is needed, or it may suggest that further evaluation is necessary before the implementation of measures to decrease the dose. For low-energy beta emitters, such as H-3, no monitoring guidelines are given. Even about Rn-222, WHO does not provide instructions on radiological risk management related to water ingestion, while it only highlights the need for monitoring the radon concentration in the air and the hazards associated with its inhalation. Consequently, screening levels for radon concentration in drinking water must be based on those currently valid for indoor air activities.

By EURATOM Council Directive n°51 of 2013 [28], the European Union adopted a parameter value, i.e., screening level, of 100 Bq/L for Rn-222 and, accordingly, for H-3 too, with an Indicative Dose (ID) of 0.1 mSv/year, which takes into account the annual effective dose from ingestion resulting from all natural and artificial nuclides but H-3, K-40, and Rn-222 [29]. Furthermore, compared to WHO, the European Commission recommends a more severe parameter value for gross alpha activity and the same for gross beta activity. These are, in fact, set to 0.1 and 1.0 Bq/L respectively. In Italy, the legislative framework that regulates the radioactivity in drinking water is given by Decree Law n°28 of 2016 [30], which implemented the 51/2013/EURATOM Directive [28], lowering the screening level for gross beta activity to 0.5 Bq/L. If the measured gross alpha and beta activity concentrations are lower than their parameter values, no further actions are required since ID < 0.1 mSv. In case one of these two parameter values is exceeded, it is required to determine the activity concentration of specific nuclides to calculate the ID, which is evaluated assuming an annual water intake of 730 L with Equation (1):

$$ID \left(mSv\right)=\sum _{i=1}^n\frac{A_i^{\left(m\right)}}{A_i^{\left(d\right)}} 0$$

(1)

with n being the number of radionuclides, while $A_i^{\left(m\right)}$ and $A_i^{\left(d\right)}$ are the measured and derived (tabulated) activity concentrations for the i-th nuclide, respectively. If ID < 0.1 mSv, no further actions are required. In cases where ID > 0.1 mSv, corrective actions are required in order to decrease the activity concentration and make them in compliance with the law. The whole control program, including risk management, is carried out by the Ministry of Health in collaboration with the Istituto Superiore di Sanità (ISS), which, through the measurement and control activities of the territorial Regional Agencies for Environmental Protection (ARPAs) and Autonomous Provinces Agencies for Environmental Protection (APPAs), can check compliance with the provisions of the law and apply any activities for public health protection.

Furthermore, in addition to the provisions of current legislation, the National Inspectorate for Nuclear Safety and Radiation Protection (ISIN), for each annual campaign of monitoring, publishes a report summarizing all the collected information and measured values about environmental radioactivity, including drinking water. Data are presented cohesively, but measurements are performed independently by 19 ARPAs, 2 APPAs, and 10 Experimental Zooprophylactic Institutes (IIZZSSs). However, published reports do not always include data regarding all 20 Italian regions, especially for radionuclides in drinking water, where the measurements are typically inhomogeneous and partially lacking. In addition, ISIN does not provide any information on Rn-222 activity concentrations in drinking water but only gross alpha, gross beta, and H-3 activity concentrations. The purpose of this work is to implement and integrate the latest reports published by ISIN by adding, whenever available, lacking data from missing regions provided by institutional laboratories (IL) to obtain a more complete outline of radioactivity in Italian drinking water.

2. Materials and Methods

2.1. Institutional Data Collection

Data published by ISIN about environmental radioactivity monitoring in Italy were considered. The reports are freely available online on the official website (www.isinucleare.it (accessed on 19 August 2023). To date, these reports contain measurements performed in 2018 [31], 2019 [32], and 2020 [33]. In each of these reports, the average of measured values of gross alpha, gross beta, and H-3 activity concentrations in drinking water performed by individual regions is presented. In these documents, the total number of measurements, including those with a value lower than the Minimum Detectable Activity (MDA), is reported. Activity concentration values from missing regions were added by searching for official data published independently by individual ARPAs and APPAs. By accessing the publication section for each official ARPA/APPA’s website, data over radionuclides in drinking water were sorted, whenever available, according to:

• Type of parameter (gross alpha, gross beta, H-3, Rn-222, and other radioisotope activity concentrations);
• Measurement year;
• Type of data (average activity concentration values, total number of measurements, number of measurements with values lower than the MDA);
• Presentation of data (tabular format, spreadsheet, histogram/graphical, interactive map).

For this work, gross alpha, gross beta, H-3, and Rn-222 activity concentrations measured during the three-year period 2018–2020 were considered. Given a specific parameter, if the average activity concentration values were available, all types of data were collected; otherwise, they were excluded. Moreover, some of the ARPAs and APPAs also give a description of the methodology used to perform the measurements, along with the provided data.

For the Campania region, measurements carried out in a UNI EN ISO 9001:2015 laboratory [34] by La Verde et al. [35,36,37] during the years 2018 and 2019 were considered. For the year 2020, given the lack of data, measurements performed by the same authors with the same methodology were included despite not being published. Details on materials and methods for gross alpha, gross beta, H-3, and Rn-222 activity concentration measurements in Campania are given in Section 2.2.

After all the data had been collected, weighted average activity concentration values were calculated, considering the total number of measurements for each Italian macro-area. According to ISIN reports, the three macro-areas are defined as follows:

(a)

North: Emilia-Romagna, Friuli-Venezia Giulia, Liguria, Lombardy, Piedmont, Trentino-Alto Adige, Aosta Valley, and Veneto.

(b)

Center: Lazio, the Marches, Tuscany, Umbria, and Sardinia.

(c)

South: Abruzzo, Basilicata, Calabria, Campania, Molise, Apulia, and Sicily.

2.2. Sampling and Radionuclide Activity Concentration Measurement in Campania

The same methodology described in the work by La Verde et al. [35] has been used to perform measurements in 2020 in Campania.

2.2.1. Sample Preparation

During 2020, a total of 13 samples were collected from sites (dwells) distributed in three water subsystems in the Campania region [35]. Additionally, 7 more samples were collected only for Rn-222 measurements from the same sampling points. Sample preparation was performed according to standard techniques and procedures [38,39,40], as summarized in

Table 1. Procedures and techniques used to perform measurements of gross alpha, gross beta, H-3, and Rn-222 activity concentrations in Campania. The calculated detection limits for each parameter are lower or equal to those required by Decree Law 28/2016 [30].

Parameter	Standard Procedure	Measurement Technique	Sample Preparation
Gross alpha	EPA 900 [38]	Alpha spectrometry	The sample is stabilized by acidification (HNO3, 1 N), transferred to a plate, and evaporated until almost complete drying.
Gross beta	EPA 900 [38]	Proportional chamber
Tritium	ISO 9698 [39]	Liquidscintillation	The sample is distilled to eliminate any chemical or radiometric interferents. An aliquot (10 mL) is transferred into a polyethylene vial with a scintillating cocktail (10 mL) and measured by liquid scintillation.
Radon	ISO 13164-1 [40]	Electret	The sample is measured without any treatment but only stored during transport at 4 °C.

.

2.2.2. Activity Concentration Measurements

For details on the instruments and methods used to perform the measurements, refer to La Verde et al. [35]. Some specifications are as follows: 1. For gross alpha activity concentration A_α measurements, the Ortec^® Alpha Duo spectrometer (Peschiera Borromeo, Milan, Italy) and the detector ULTRA-AS, with an efficiency of 0.0332, were used. For gross beta activity concentration Aβ measurements, the proportional counter Berthold Technologies Umo LB 123, with an efficiency of 0.105, was used. Both activities were calculated with Equation (2):

$$A_{a,\beta } \left(\frac{Bq}{L}\right)=\frac{CP{S}_{net}}{Efficienc{y}_{a,\beta }}\cdot \frac{1}{V}$$

(2)

where V = 0.05 l is the sample volume and CPS_net is the net counts per second obtained after background count subtraction.

2. For H-3 activity concentration A_H-3 measurements, the PerkinElmer^® Wallac 1220 Quantulus liquid scintillator was used. After having determined the background counts, A_BKG Equation (3) was used to evaluate the net H-3 activity after measuring the activity in the sample A_T.

$$A_{H-3} \left(\frac{Bq}{L}\right)=A_T-A_{BKG}$$

(3)

3. For Rn-222 in water activity concentration and $A_{Rn-222}^{water}$ measurements, the Electret Ion Chamber (EIC) E-Perm^® system was used. Equations (4)–(6) were used for the evaluation:

$$A_{Rn-222}^{water}=A_{Rn-222}^{air}\cdot B_1\cdot B_2\cdot B_3$$

(4)

$$A_{Rn-222}^{air}=\left[\frac{V_i-V_f}{CF\cdot T}-G_{\gamma }\cdot C_1\right]\cdot 37$$

(5)

$$CF=C_2+C_3\cdot \frac{V_i+V_f}{2}$$

(6)

where $A_{Rn-222}^{air}$ is the radon concentration in the air inside the jar; B₁ considers the delay period between the collection of the sample and the start of the measurement. B₂ is a constant based on the analysis period. B₃ is the ratio between the jar and water sample volumes. V_i and V_f are the electret voltages before and after the exposure, respectively. T is the exposure time. G_γ is the background signal due to gamma radiation, and C₁ = 0.097, C₂ = 1.670, and C₃ = 5.742 × 10⁻⁴ are constants provided by the instrumentation manufacturer; CF is the calibration factor.

3. Results and Discussions

Among all the 21 ARPAs and APPAs, only 12 of them have published the results of at least one measurement campaign since 2016 (i.e., the year of the Italian Decree Law n°28 [30]). However, among these 12, only 6 met the following criteria for at least one parameter:

• To provide the precise result of average activity concentration for at least one year between 2018 and 2020;
• To provide the total number of measurements;
• Not to be included in any considered ISIN report.

Subsections with summarized data for each parameter will follow. More specifically, the average activity concentration values (A), the total number of measurements performed (N), and the number of measurements with values lower than the MDA (N < MDA) (annex III

Table 2. Measurements of Gross alpha activity concentrations in Italian drinking water in 2018–2020. “N” indicates the total number of measurements, “N < MDA” indicates the total number of measurements with activity lower than the MDA of 0.04 Bq/L as indicated in annex III, Table 2 of [30], and “A” indicates the average activity concentration values. The sign “-“ indicates that data were already published by ISIN; “na” stands for “not available”; colored in gray are data published by ARPAs indicated in the “Ref.” column that are not included in ISIN reports for a specific year. Data by La Verde et al. [35] for the Campania region are also colored gray. All other values are taken from ISIN reports.

Gross Alpha		2018			2019			2020			Ref.
Macro-areas	Region	N	N < MDA	A (Bq/L)	N	N < MDA	A (Bq/L)	N	N < MDA	A (Bq/L)
North	Lombardy	112	17	0.054	86	12	0.078	67	5	0.087	[31,32,33]
	Piedmont	28	17	0.049	306	110	<0.035	322	167	0.042
	Emilia-Romagna	4	4	<0.018	63	39	<0.032	na	na	na
	Liguria	na	na	na	144	65	0.056	401	304	0.044
	Friuli-Venezia Giulia	na	na	na	74	8	0.043	77	4	0.046
Center	Lazio	2	1	0.054	2	0	0.040	2	1	0.061
	The Marches	29	17	<0.035	38	17	0.042	18	6	<0.029
	Tuscany	47	23	<0.034	65	25	<0.036	na	na	na
	Umbria	na	na	na	96	2	0.047	67	0	0.043
	Sardinia	na	na	na	na	na	na	41	40	0.072
South	Basilicata	4	3	<0.022	6	3	0.046	2	2	0.152
	Calabria	189	77	0.062	208	107	0.055	179	68	0.076
	Campania	29	14	<0.123	1	0	0.079	na	na	na
	Apulia	na	na	na	na	na	na	10	4	<0.033
North	Veneto	228	175	0.040	471	293	0.042	407	284	0.041	[41]
Center	Tuscany	-	-	-	-	-	-	221	na	<0.038	[42]
	Sardinia	14	9	0.052	56	22	0.044	-	-	-	[43]
South	Campania	55	20	<0.038	28	14	<0.035	13 *	4 *	0.055 *	[35]

* Unpublished data.

of [30]) will be reported for each parameter, relative to the years 2018, 2019, and 2020. The average activity concentration values for each region and each parameter were computed as the arithmetic mean of measurements performed and published by single ARPA/APPAs, as previously explained; in cases of measures lower than the MDA, the MDA value was considered for the calculation.

3.1. Gross Alpha Activity Concentration

For gross alpha activity concentrations, data from four regions was added with respect to ISIN reports. Measurements performed in Veneto [41], Tuscany [42], Sardinia [43], and Campania [35] between 2018 and 2020, together with values provided by ISIN for gross alpha activity concentration, are shown in Table 2.

3.2. Gross Beta Activity Concentration

For gross beta activity concentrations, data from three regions was added with respect to ISIN reports. Measurements performed in Tuscany [42], Sardinia [43], and Campania [35] between 2018 and 2020, together with values provided by ISIN for gross beta activity concentration, are shown in

Table 3. Measurements of Gross beta activity concentrations in Italian drinking water in 2018–2020. “N” indicates the total number of measurements, “N < MDA” indicates the total number of measurements with activity lower than the MDA of 0.2 Bq/L as indicated in annex III, Table 2 of [30], and “A” indicates the average activity concentration values. The sign “-“ indicates that data were already published by ISIN; “na” stands for “not available”; colored in gray are data published by ARPAs indicated in the “Ref.” column that are not included in ISIN reports for a specific year. Data by La Verde et al. [35] for the Campania region are also colored gray. All other values are taken from ISIN reports.

Gross Beta		2018			2019			2020			Ref.
Macro-areas	Region	N	N < MDA	A (Bq/L)	N	N < MDA	A (Bq/L)	N	N < MDA	A (Bq/L)
North	Lombardy	112	64	<0.100	86	59	<0.137	67	50	<0.133	[31,32,33]
	Piedmont	40	30	<0.141	326	162	<0.114	322	152	<0.110
	Emilia-Romagna	4	0	<0.084	63	0	<0.067	na	na	na
	Liguria	na	na	na	155	102	0.292	401	389	0.257
	Friuli-Venezia Giulia	na	na	na	74	32	<0.193	77	5	0.231
Center	Lazio	2	1	<0.153	2	1	<0.170	2	0	0.741
	The Marches	29	2	<0.189	38	22	<0.121	18	13	<0.083
	Tuscany	47	22	<0.125	65	43	<0.145	na	na	na
	Umbria	na	na	na	96	15	<0.116	67	4	<0.153
	Sardinia	na	na	na	na	na	na	41	12	<0.147
South	Basilicata	4	0	0.204	7	0	0.295	2	1	0.310
	Calabria	189	152	0.218	208	184	0.209	179	142	0.221
	Campania	29	1	0.423	na	na	na	na	na	na
	Apulia	na	na	na	1	0	<0.156	10	1	<0.168
Center	Tuscany	-	-	-	-	-	-	221	na	<0.161	[42]
	Sardinia	14	9	0.251	56	40	<0.136	-	-	-	[43]
South	Campania	-	-	-	28	17	0.221	13 *	12 *	0.212 *	[35]

* Unpublished data.

.

3.3. Tritium Activity Concentration

For H-3 activity concentrations, no data was found from all the ARPAs and APPAs websites; therefore, only measurements performed by La Verde et al. [35] were included for years 2019 and 2020.

Table 4. Measurements of H-3 activity concentrations in Italian drinking water in 2018–2020. “N” indicates the total number of measurements, and “A” indicates the average activity concentration values. The sign “-“ indicates that data were already published by ISIN; “na” stands for “not available”; colored in gray are data published by La Verde et al. [35] for the Campania region. All other values are taken from ISIN reports.

H-3		2018		2019		2020		Ref.
Macro-areas	Region	N	A (Bq/L)	N	A (Bq/L)	N	A (Bq/L)
North	Lombardy	47	5.42	14	4.66	14	6.20	[31,32,33]
	Piedmont	24	1.97	25	1.86	20	2.86
	Emilia-Romagna	5	1.33	4	1.65	na	na
	Veneto	4	2.50	na	na	na	na
Center	Lazio	2	8.60	2	8.05	2	4.85
South	Basilicata	4	2.76	8	2.16	2	2.03
	Calabria	187	10.1	199	10.0	156	10.0
	Campania	29	3.00	na	na	na	na
	Apulia	na	na	1	5.90	7	<6.40
South	Campania	-	-	28	2.72	13 *	10.0 *	[35]

* Unpublished data.

presents all the reported values of H-3 activity concentration in the three years. Given that most measured values are lower than the MDA of 10 Bq/L indicated in annex III, Table 2 of [30], we considered MDA values reported by ISIN.

3.4. Radon Activity Concentration

For Rn-222 activity concentrations, data from seven regions were included. Measurements performed in Lombardy [44,45], Veneto [41], Lazio [46], The Marches [47], Tuscany [42], Sardinia [43], and Campania [35] between 2018 and 2020 are shown in

Table 5. Measurements of Rn-222 activity concentrations in Italian drinking water in 2018–2020. “N” indicates the total number of measurements, and “A” indicates the average activity concentration values. “na” stands for “not available." All data are from ARPAs and La Verde et al. [35], given that Rn-222 activity concentration is not included in ISIN reports.

Rn-222		2018		2019		2020		Ref.
Macro-areas	Region	N	A (Bq/L)	N	A (Bq/L)	N	A (Bq/L)
North	Lombardy	na	na	72	11.9	66	11.4	[44,45]
	Veneto	264	8.70	475	8.10	393	8.30	[41]
Center	Lazio	6	37.3	15	27.7	3	21.3	[46]
	The Marches	17	2.56	na	na	na	na	[47]
	Tuscany	na	na	181	7.28	156	12.5	[42]
	Sardinia	4	2.60	22	8.00	na	na	[43]
South	Campania	55	16.2	28	11.7	20 *	12.8 *	[35]

* Unpublished data.

. Note that none of these measurements are reported in any ISIN report. Given that most measured values are lower than the MDA of 10 Bq/L indicated in annex III, Table 2 of [30], we considered MDA values reported by ISIN.

3.5. Comparisons between ISIN and Institutional Laboratories Data

To perform a comparison between measurements provided by ISIN and institutional laboratories (ARPAs and, for the Campania region, La Verde et al. [35]), the weighted average for each parameter in all three Italian macro-areas was calculated using the total number of measurements as weights. Results are shown in

Table 6. Values of weighted average H-3, gross alpha, gross beta, and Rn-222 activity concentrations in Italian drinking water in 2018–2020 for individual macro-areas. The sign “-“for Rn-222 values in ISIN columns indicates that data is lacking in reports. Institutional laboratories (IL) are ARPAs and La Verde et al. (details on single regions for each Macro-area are listed in Table 2, Table 3, Table 4 and Table 5).

		2018		2019		2020
Parameter	Macro-area	ISIN	ISIN + IL	ISIN	ISIN + IL	ISIN	ISIN + IL
Tritium (Bq/L)	North	3.97	3.97	2.80	2.80	4.24	4.24
	Center	8.60	8.60	8.10	8.10	4.85	4.85
	South	9.07	8.75	9.70	8.90	9.88	9.77
Gross alpha (Bq/L)	North	0.052	0.044	0.044	0.044	0.047	0.045
	Center	<0.035	<0.037	0.043	0.043	0.051	0.043
	South	0.070	0.064	0.053	0.053	0.075	0.073
Gross beta (Bq/L)	North	<0.11	<0.11	<0.16	<0.16	<0.19	<0.19
	Center	<0.15	<0.16	<0.13	<0.13	<0.15	<0.16
	South	0.24	0.24	0.21	0.21	0.22	0.22
Radon (Bq/L)	North	-	8.7	-	8.6	-	8.7
	Center	-	10.3	-	8.8	-	12.7
	South	-	16.2	-	11.7	-	12.8

, which presents data reported in ISIN publications and data obtained by integrating ISIN ones with IL ones (ISIN + IL).

As can be seen from the values in Table 6, integrated values are not significantly different from the ones published by ISIN. This highlights how, despite not including measurements from all the 20 Italian regions, those reports are extremely effective and representative of the radioactivity distribution in drinking water. However, results indicate that small variations are still present, meaning that including more regions, that is, more measurements for each macro-area, allows for more detailed information on parameter values with higher statistics. Furthermore, independent research of official published data allowed us to collect additional information, such as the Rn-222 distribution in Italian drinking water, which was missing in ISIN reports.

Figure 1, Figure 2, Figure 3 and Figure 4 represent data from Table 6 in graphical format. Each figure shows a bar graph of activity concentration for a specific parameter in the three-year period considered (2018–2020) and for each Macro-area.

As can be seen from Figure 1, Figure 2, Figure 3 and Figure 4, the average activity concentrations for each parameter are greater in the south of Italy compared to the center and north, probably due to the peculiar hydrogeological features of the macro-area, which is characterized by volcanic soils and territories with singular lithological traits that strongly influence environmental radioactivity. However, all average activity concentrations are lower than the screening levels/parameter values indicated in the law [30]. Also, the majority of results are even lower than the MDAs given in the law [30]: as shown in Figure 2, the only exception relies on the gross alpha average measurements, which are all above 0.04 Bq/L, excluding data from the center of Italy obtained in 2018.

3.6. Comparisons with Literature Data

Results found in the literature over radioactivity measurements in Italian drinking waters are in good agreement with both ISIN and the upgraded scenarios presented in Table 6. In the Calabria region, gross alpha and gross beta measurements vary in the ranges <0.04–0.16 and <0.20–0.34 Bq/L, respectively [48], in line with values obtained from South Italy. In addition, in the Calabria region, the average reported Rn-222 activity concentration is 24.4 Bq/L (1.6–94.0 Bq/L) [49]. These values are higher compared to the ones reported in this study, but very few data are available about Rn-222. Moreover, they’re always lower than the legislative limit. Still in South Italy, some measurements of Rn-222 are reported to be on average equal to 4.6 Bq/L (1.0–12.7 Bq/L) for Sicily [50] and 17 Bq/L (3.0–45.0 Bq/L) for Campania [51]. In the Umbria region of central Italy, Rn-222 measurements ranged between 5.9 and 65.8 Bq/L [52], still higher than the ones in this study. The same authors also provided data on H-3 activity concentration, with values lower than the calculated MDA of 8.6 Bq/L [52]. Measurements performed in The Marchs are in good agreement with all parameters reported in Table 6: Gross alpha and beta values are reported to be in the ranges <0.018–0.128 Bq/L and <0.042–0.259 Bq/L, respectively [53], while average Rn-222 and H-3 activity concentrations are 6.12 Bq/L (0.69–20.3 Bq/L) and <6.75 Bq/L, respectively [54].

Measurements performed in 13 cities in Lombardy are reported to be, on average, 0.062 Bq/L (<0.008–0.349 Bq/L), 0.144 Bq/L (<0.025–0.273 Bq/L), and <6.8 Bq/L for gross alpha, gross beta, and Radon activity concentrations, respectively [55]. The accordance for gross alpha, gross beta, and H-3 concentrations between the literature and the data reported in this study is fairly good [29]. However, it is advisable to perform a higher number of measurements, especially of Rn-222 activity concentrations in drinking water, given the low number of available statistics.

4. Conclusions

This work integrates official data on radioactivity monitoring in Italian drinking water. For the specific case, measurements elaborated and published by ISIN in annual reports were implemented with values taken from institutional sources and laboratories. Comparisons between ISIN and updated values showed that published reports are representative of the Italian framework on radionuclides in drinking water, although the same reports are incomplete since many regions are not included. In the future, it could be interesting to create a network of information flows in order to merge them into a single document that could be continuously updated to obtain a more detailed distribution of radioactivity in Italian drinking water. Institutional laboratories, for example, could have access to a database and upload data. Given this scenario, an intrinsic limitation of such a network could be the lack of data published by laboratories. The unavailability of measurements, together with a poor description of methodology and other missing information, could make collecting and updating data on radioactivity in drinking water challenging. Nevertheless, the creation of this kind of database would also promote more in-depth investigations for Italian regions with few/no measurements, providing not only for regulatory compliance but also for a more extensive radio protection program.