9 Regulatory Standards Setby Various Bodies Regulat ory standards, or health-bas ed guidan ce values , in this chapte r denote d ‘‘guidan ce values, ’’ for exposur e to chemi cals in var
Trang 19 Regulatory Standards Set
by Various Bodies
Regulat ory standards, or health-bas ed guidan ce values , in this chapte r denote d ‘‘guidan ce values, ’’ for exposur e to chemi cals in various medi a such as air, drink ing water, soil , and food are set by vario us international , federal , and nationa l bodies This chapte r will give an overview of the develo pment of guidanc e values in general term s and presen t some examp les
9.1 GUIDANCE VALUES: DEVELOPMENT
This section gives an overvi ew of the develo pment of guidance values in general term s
Acco rding to the OECD=IPC S de finitions listed in Annex 1 (OECD 200 3):
Guidanc e Value is ‘‘Valu e, such as concent ration in air or water, which is deriv ed after allocati on of the reference dose among the different possible media (routes) of exposur e ’’ Combi ned exposur es from all media at thei r respec tive guidan ce values over a lifetime woul d be expect ed to be without ap preciable health risk The aim of a guidan ce value is to provi de quantitat ive infor mation from risk asses smen t for risk manag ers to enable them to make decisions concern ing the prote ction of human health
Guidanc e values are de veloped from a stand ard such as, e.g., an Acce ptable=Tolerable Daily Intake (ADI=TDI), and Reference Dose=Concentration (RfD=RfC) For threshold effects, the standard
is d erived by divi ding the No- Obser Adve rse-Effect Level (NOA EL) or Lowes t-Obser ved-Adve rse-Effect Level (LOAE L), or alternatively a Ben chmark Dos e (BMD ) for the critical effect (s) b y an overall asses sment factor, descri bed in detail in Cha pter 5 Fo r non-thresho ld effects, the stand ard is d erived by a qu antitative assessmen t, described in detai l in Chapter 6
To the extent possible, guidan ce v alues shoul d re flect consideration of tota l exposur e to the substance whether presen t in air, drinking water, soil , food, or other media Guidance values should
be derived for a clearly defined exposure scenario, e.g., for ambient air, drinking water, and soil based on the human exposur e facto rs presen ted in Section 7.3 It shoul d be recogni zed that there are
no internationa lly agreed stand ard values for human exposur e facto rs, and the examples presen ted in Secti on 7.3 serve to illust rate the diff erences in exposur e facto rs provi ded by various exposur e facto r docum ents Such differences can have a great impa ct on the guidance values, and it is therefore important that the most relevant and reliable exposure factors are used for the particular situation The development of guidance values for chemicals present in more than one environmental medium will require the allocation of proportions of the tolerable intake to various media based on information on relative proportion of total exposure from each of the media If possible, estimation
of exposure should be based on concentrations in the environmental media including ambient air, drinking water, soil, and food as well as consumer products Unless there are age groups being more sensitive or having widely differing exposure profiles, the intake from each of the media should be estimated for adults, e.g., for ambient air, drinking water, and soil based on the human exposure factors presented in Section 7.3 If the data on concentrations of a substance in environmental media are inconsistent or inadequate, exposure could be estimated based on models, which incorporate
as much data as possible on, e.g., production, use patterns, and physico-chemical properties
Trang 2An examp le of an exposur e model to predict dist ribution in envir onmen tal media and esti mation of the proportion of total exposur e by vario us route s from consum er product s is the EUSE S (S ection 7.2.4.3) It is imp ortant to recogni ze that the propor tions of total inta ke from vario us media may vary, based on circu mstances
It shoul d be noted that a source in one medi um may lead to addit ional inta ke from other routes, e.g., for drink ing wat er, dermal and inhal ation exposur e may occur during a shower, and for soil, exposur e would often b e both via ingestio n and dermal c ontact; when possi ble, such inta ke shoul d also b e consi dered in the derivatio n of guidan ce values
Total allo cations of less than 100% of the tole rable inta ke are recommend ed to account for, e.g., those medi a for whi ch exposur e has not been charact erize d, and crossrout e exposur e The propor -tion of the total intake, which is not allocated, shoul d vary accordi ng to the adequacy of the exposur e characte rization from all media
The preci sion of the guidan ce value is dependen t upon the validit y and relia bility of the available data In addit ion to the impact on the guidanc e value from the choice of an exposur e facto r as ment ioned above, there are often sources of uncertaint y in the derivatio n of the tolerable intake (Secti on 5.12) and in thei r allocati on as a basis for the guidance v alues The resulting guidance values thus represen t a best estimat e based on the available data at the time of develo pment The numer ical value of a guidan ce value shoul d re fl ect the precision in its deriv ation, and shoul d usual ly be given to only one signi fican t figure
Gui dance values can be set for the general popula tion, occupat ional ly exposed popula tion, as well as for suscep tible subgro ups The approac h for sett ing guidanc e values in the ambient e nviron-ment , i.e., ambi ent air, d rinking water, soil, food, and other media relates prima rily to long- term exposur e of the general popula tion Some degree of human varia bility is taken into account in the asses sment factors appli ed in the derivatio n of the tolerable intak e (Chapte r 5) Where a u niquely sensitive group forms a signi fican t proportion of the populatio n, the tole rable intake could be deriv ed based on that group In cases where the exposur e pro files of this subgro up and the general popula tion are simil ar, the guidan ce values shoul d be based on the tolerable inta ke for the sensi tive subgro up If the exposur e pro fi les diff er, guidan ce values shoul d be calcul ated separa tely for the subgro up and general populatio n based on their respec tive tolerable intakes and exposur e pro files, and the more conservati ve va lues adopted The approac h for setting gu idance values relating to intermi t-tent , short-ter m (e.g., accidental), and occ upational exposures is basically similar to that for long-term exposure although there might be other considerations to take into account
9.2 GUIDANCE VALUES: EXAMPLES
Various international, federal, and national bodies set guidance values for exposure to chemicals in various media such as air, drinking water, soil, and food This section will present some examples of guidance values set by the WHO representing an international body, the US-EPA and the EU representing federal bodies, and Denmark representing a national body
9.2.1 WHO
Examples of guidance values developed by the WHO include‘‘air quality guidelines’’ and ‘‘drink-ing water guidelines,’’ and (in collaboration with the FAO) ‘‘maximum residue limits’’ (MRLs) for pesticides and veterinary drugs and‘‘maximum levels’’ for food additives
9.2.1.1 Air Quality Guidelines
Recognizing the need of humans for clean air, the WHO Regional Office for Europe in 1987 published the first edition of the ‘‘Air Quality Guidelines for Europe’’ containing health risk assessments of 28 chemical air contaminants (WHO 1987) In 1993, air pollutants of special environmental and health significance to countries of the European Region were identified by a
Trang 3WHO planni ng group, and 35 air pollutant s were selected to be incl uded in a second edition of the Air Qualit y Guidelines , whi ch was publi shed in 2000 (WHO 2000) It is noted that relev ant EHC docum ents (Section 3.6.1.1) wer e of great value with respect to the selec tion of pollu tions to be included in the second edition of the Air Qual ity Guid elines (WH O 2000) The publi cation is available via the WHO Regional Of fice for Europ e ’s Web site (WHO 2007 b)
The second edit ion of the Air Qual ity Gui delines for Euro pe (WHO 2000) comprises four introduct ory chapters plus sectio ns on health risk evalua tion and guidelines of the variou s pollu tants The intr oducto ry Cha pter 1 of the Air Quality Guide lines sets the scene regarding air quality issues, states the natur e of the air quali ty guidel ines, and de scribes the procedu res used in the updating and revision proces s In the following text , the most essent ial informat ion in the contex t of this book is presen ted
The second edition is limited to summari es o f the data on whi ch the guidelines are based; the full backgro und evalua tion shoul d becom e progre ssiv ely avail able on the WHO Regional Of fice for Europe ’ s Web site (WH O 2007b) As in the fi rst e dition, detai led referencing of the relev ant literat ure has been provi ded with indicati ons of the periods cov ered by the reviews of individua l pollutant s
The primary aim of the guidelines is to provi de a basis for protectin g public healt h from advers e effects of air poll ution and for elimin ating, or reducing to a min imum, those contamina nts of air that are known or like ly to be hazardo us to human healt h and well-b eing The guidelines are intended to provi de backgro und infor mation and guidan ce to g overnments in makin g risk manag ement decis ions, particula rly as a basis for sett ing stand ards or limit values for air contam inants
The guidelines are not restrict ed to a numerical value below whi ch exposur e for a given perio d
of time does not const itute a signi fi cant health risk ; they also incl ude any kind of recom mendation or guidan ce in the relev ant field Numerical values either indi cate the airbo rne concent ration of a chemica l combi ned wi th exposur e times at whi ch no advers e effect is expecte d in terms of noncarc inogen ic endpoi nts, or they provide an estimat e of lif etime cancer risk arising from those substanc es that a re proven human carcinogen s or carci nogens wi th at least limited eviden ce of human carci nogeni city It is point ed out that the risk estimates for carcinogens do not indi cate a safe level, but they are presen ted so that the carci nogeni c potencies of diff erent carcinog ens can be compa red and an asses sment of overall risk made The guidel ines, including numer ical values , are further addres sed in the intr oducto ry Cha pter 3 of the Air Qual ity Guideline s (WH O 2000) When numerical guideline v alues are given, these values are not standa rds in themselv es Before trans forming them into legal ly binding standards, the g uideline values must be consi dered
in the contex t of prevailin g exposur e levels, technical feasi bility, source contr ol meas ures, abate-ment stra tegies, and socia l, econom ic, and cult ural con ditions; this is furth er add ressed in the introduct ory Chapter 4 of the Air Qualit y Gui delines (WHO 2000 )
It is stat ed that inhal ation of an air poll utant in concent rations and for exposur e times below a guideline value will not ha ve adverse e ffects on health; howe ver, complianc e with recom menda tions regard ing guidel ine v alues does not guarant ee the absolute exclusion of effects at levels below such values As an examp le it is mentioned that highly sensiti ve groups such as those imp aired by concurr ent disea se or other p hysiologi cal limitati ons may be affected at or near concent rations referred to in the guideline values Health effect s at or below guideline values may also resul t from combine d exposur e to various chemicals or from exposur e to the same chemi cal by mul tiple route s
It has been agreed with the EU Comm ission that the fi nal d rafts of the revised WHO guideline docum ents woul d provi de a starting po int for discu ssions by the Commiss ion ’s working groups aiming at sett ing legally binding limit values for air q uality in the EU, see Section 9.2.4.1 The introduct ory Chapter 2 of the Air Quality Guidelines (WHO 2000) gives a very detailed and compr ehensive descri ption of the crit eria used in estab lishing the guidel ine values including criteria for selec tion of NOA EL=LOA EL, advers e effect , benchm ark approac h, and uncertaint y facto rs These criteria are compa rable to the principle s outlined in Chapter s 4 and 5 in this book There are also criteria for selection of averaging times and for consideration of sensory effects (malodorous
Trang 4proper ties at conc entration s far below those at which toxi c effect s occur) In addition, there are criteria for carci nogeni c endpoi nt incl uding qualitat ive assessmen t of carci nogeni city, qua ntitative asses sment of carcinogeni c potenc y, quantitat ive asses smen t of carcinogen icity b ased on human data, risk estimat es from animal cancer bioas says, and inte rpretati on o f risk estimates; these crite ria are compa rable to the princ iples outl ined in Cha pter 6 in this book It is speci fically point ed out that durin g the prepar ation of this second edition of the g uidelines , attentio n was paid to de fining speci fic sensi tive subgro ups in the popula tion
WHO global air quality gu idelines are available for the following air poll utants: parti culate mat ter, ozone, nitroge n dioxide, and sulf ur dioxi de The latest revis ion, which was p ublished
in 200 5, subst antially lowered the recom mende d limit s of pa rticulate matter, ozone, and sulfur dioxi de The publicatio n is a vailable via the WHO Reg ional Of fice for Europ e ’s Web site (WH O 2007b)
9.2.1 2 Drin king-Water Guide lines
The WHO published the first and second editions of the ‘‘ Guidelin es for Drinki ng-wate r Qualit y ,’’
in three volum es, in 1984 –1985 and in 1993 –1997, respec tive ly The fi rst edit ion contains health risk asses sments of 36 inorg anic const ituents and physical pa rameters , 27 organic compo unds, 30 pesticide s, 4 disinfect ants, 5 disinfect ant by-products , and 6 other chlorinat ion by-pro ducts The second edition contai ns healt h risk assessmen ts of 6 inorg anic constitu ents (updat ed), 3 organi c compo unds (1 new, 2 update d), 10 pesticide s (7 new, 3 update d), and 1 disinfect ant by-pro duct (new ) A third edition of Volume 1 was published in 200 4 The Gui delines are k ept u p to date by a
‘‘ rolling revision ’’ and a fourt h edition is schedu led for 2008 The publicati ons are avail able to the publi c via the WHO Water Sanitatio n and Heal th Web site (WHO 2 007a)
Vol ume 1 ‘‘Recomm endations ’’ addres ses requi reme nts to ensure drinking-wat er safety, includ-ing min imum procedu res and speci fic guidel ine values, and how those requi reme nts a re intended to
be used The volum e also describes the approac hes used in deriving the guidelines , including guidel ine values It includes fact sheet s on signi ficant microbial and chemical hazards Cha pter 12 provi des the fact sheet s for the indi vidual ch emical contamina nts evalua ted Fo r those contam inants for which a guideline value has been estab lished, the fact sheet s inclu de a brief toxi cological overvi ew of the chemi cal, the basis for guidel ine derivation, treat ment achievabil ity, and analyt ical limit of detection
Volume 2,‘‘Health Criteria and other Supporting Information,’’ explains how guideline values for the contaminants are to be used, defines the criteria used to select the various chemical, physical, microbiological, and radiological contaminants included, describes the approaches used in deriving guideline values, and presents, in the form of brief monographs, critical reviews and evaluations of the effects on human health of the substances or contaminants examined The introductory chapter
of Volume 2, second edition (WHO 1996), sets the scene regarding drinking-water quality issues, gives some general considerations, states the nature of the drinking-water quality guidelines, and describes the criteria for the selection of health-related drinking-water contaminants In the follow-ing text, the most essential information in the context of this book is presented
The primary aim of the Guidelines for Drinking-water Quality is the protection of public health The guidelines are addressed primarily to water and health regulators, policymakers and their advisors and intended to be used as a basis for the development of national standards that may ensure the safety of drinking-water supplies through the elimination, or reduction to a minimum concentration, of constituents of water that are known to be hazardous to health It is pointed out that the guideline values recommended are not mandatory limits as, in order to define such limits, it is necessary to consider the guideline values in the context of local or national environmental, social, economic, and cultural conditions
It is noted that the problems associated with chemical constituents of drinking water arise primarily from their ability to cause adverse health effects after prolonged periods of exposure, and
Trang 5it is point ed out that of particula r concern are contamina nts that hav e cumulati ve toxic proper ties such as heavy met als and carcinogeni c subst ances It is also pointed out that the use of chemical disinfect ants in wat er treatmen t u sually resul ts in the formati on of chemical by-produ cts, some of which are potential ly hazardo us
Guideli ne values have been set for potent ially hazardo us wat er const ituents an d provi de a basis for assessing drink ing-water quali ty A guidel ine value repres ents the concent ration of a const ituent that doe s not resul t in any signi ficant risk to the health of the consumer over a lif etime of consum ption However , it is empha sized that the guidel ine values should not be regard ed as implyi ng that the quali ty of drink ing water may be degrade d to the recom mende d level It is point ed out that short-ter m deviations above the guidel ine values do not necess arily mean that the water is unsui table for consumpti on The amoun t by which, and the perio d for whi ch, any guideline value can be exceeded without affecting public healt h depend s upon the speci fic substa nce invol ved
In some instances, provision al guidel ine values have been set for constitu ents for whi ch there is some eviden ce of a potent ial hazard but wher e the avail able informat ion on health effects is limit ed Provis ional guidel ine values have also been set for subst ances for whi ch the calcul ated guideline value would be below the practical quanti ficati on level, or below the level that can be achiev ed throu gh pract ical treatmen t methods, as well as for certa in subst ances when it is likely that guideline values wi ll be exc eeded as a result of disin fection procedu res
It is stated that thousands of c hemicals have been ident i fied in drinking-w ater suppl ies around the world, many in extre mely low concent rations The chemi cals selec ted for the develo pment of guideline values includ e those consi dered potentially hazardo us to human health, those detect ed relativel y freque ntly in drinking water, and those detect ed in relatively high concent rations Cha pter 12 of Volume 2, second edit ion (WH O 1996), gives a detailed and compr ehensi ve descripti on of the principle s used in estab lishing the guidel ine values
The asses smen t of the toxicit y of drink ing-wat er contamina nts has been made on the basis of published reports from the ope n literat ure, informat ion subm itted by go vernments and other inter-ested p arties, and unpublishe d propri etary data In the develo pment of the guidel ine values , existing internati onal approac hes to developing guidel ines were careful ly consi dered Previo us risk a ssess-ments develo ped by the WHO=IPC S in EHC monog raphs (see Section 3.6.1.1), IARC (see Secti on 3.6.1.2), JMPR (see Section 3.6.1.3), and JECFA (see Secti on 3.6.1.3) were reviewed The se asses sments were relied upon except where new infor mation justi fied a reassessm ent The quality
of new data was critically evaluated prior to their use in risk assessmen t
The section on de rivation of guidel ine values using a tolerable daily inta ke (T DI) incl udes criteria for derivatio n of a TDI from a NOA EL o r LOA EL by applicati on of uncertaint y factors; these crit eria are comparable to the principle s ou tlined in Chapter s 4 and 5 in this boo k The guideline value is then derived from the TDI as follows:
GV ¼ [TDI bw P]=C where
bw¼ body weight (60 kg for adults, 10 kg for children, 5 kg for infants)
P ¼ proportion of the TDI allocated to drinking water
C ¼ daily drinking-water consumption (2 L for adults, 1 L for children, 0.75 L for infants)
In many cases, the intake of a chemical from drinking water is small in comparison with that from other sources such as food and air Guideline values derived using the TDI approach take into account exposure from all sources by allocating a percentage of the TDI to drinking water When possible, data concerning the proportion of total intake normally ingested in drinking water (based
on mean levels in food, air, and drinking water) or intakes estimated on the basis of consideration of physical and chemical properties were used in the derivation of the guideline values Where such information was not available, an arbitrary (default) value of 10% for drinking water was used
Trang 6This defaul t v alue was considered, in most cases, to be suf ficient to account for additional routes of inta ke, i.e., inhalati on and derm al absorp tion of contam inants in water
The re is also a section on deriv ation of guidel ine va lues for potent ial carci nogens; the criteria in this section are compa rable to the princ iples outlined in Chapter 6 in this book
Vol ume 3 ‘‘Su rveillanc e and contr ol of comm unity suppl ies ’’ contai ns recom mendation s and infor mation concern ing what needs to be done in small comm unities, particula rly in deve loping countr ies, to safeguard their water suppl ies
9.2.1 3 Foo d
The Codex Alimentar ius Commiss ion was creat ed in 1963 by FAO and WHO to develo p food stand ards, guidel ines, and relat ed text s such as codes of practice under the Joint FAO=WHO Food Standar ds Program The mai n purpos es of this Program are to protect the healt h o f the consum ers and to ensure fair trade practices in the food trade, and to promote the coordi nation of all food standards wor k un dertaken by inte rnational governm ental and nongover nmental o rganiza-tion s (CA 2007)
The Codex Al imentarius is a colle ction of stand ards, codes of practice, guidel ines, and other recom menda tions Some of these texts are very general, and some are very speci fi c Some deal with detai led requi rements related to a food or group of foods; others deal with the operation and manag ement of product ion proces ses or the operat ion of governm ent regul atory systems for food safet y and consum er p rotection
The main FAO=WHO expert bodies incl ude the Joint FAO=WHO Expert Comm ittee on Food Additi ves (JECFA) , the Joint FAO=W HO Meetings on Pesticide Residue s (JMPR) , and the Joint FAO= W HO Exp ert Meetings on Micr obiologic al Risk Assessme nt (JEMRA ) Cod ex Alim entar ius provi des lists of MRLs for pesti cides a nd veterinary drugs, and maxi mum level s for food additives The Joint FAO=WHO Expert Comm ittee on Food Addi tives (JECFA) was estab lished in 1955
to consi der chemical, toxi cological, and other aspects of contamina nts and residue s of veterinary drugs in foods for human consum ption The Cod ex Committ ee on Food Addi tives and Contamin-ants and the Code x Comm ittee on Residue s of Veterin ary Drug s in Fo ods identify food additives , contam inants, and veter inary drug residues that shoul d recei ve priority evalua tion and refer them to JECFA for assessmen t before incor porating them into Code x stand ards
The Joint FAO=WHO Meet ings on Pesti cide Res idues (JMPR) began wor k in 196 3 foll owing a decis ion that the Codex Alim entarius Comm ission should recommend MRLs for pesticide s and envir onmen tal contamina nts in speci fic food p roducts to ensure the safety of foods containing resi dues It was also decide d that JMPR shoul d recom mend met hods of samp ling and analysis The re is close coopera tion betw een JMPR and the Codex Com mittee on Pesticide Residue s (CCPR) CCPR identi fies those substances requi ring priority evalua tion After JMPR evalua tion, CCPR discu sses the recommend ed MRL s and, if they are accept able, forwards them to the Comm ission for adopti on as Cod ex MR Ls
The Joint FAO=WHO Expert Meet ings on Microbiol ogical Risk Ass essment (JE MRA) began wor k in 2000 to develo p and provide advice to the Cod ex Alim entarius Comm ission on mic robio-logi cal aspect s of food safety In addit ion to provi ding risk asses sments, JE MRA develo ps guidan ce
on related areas such as data coll ection and the applica tion of risk asses smen t JEMRA wor ks most close ly with the Cod ex Comm ittee on Food Hygiene, but has also provi ded advice to other Codex comm ittees, such as the Comm ittee on Fish and Fisher y Produc ts
The U.S Env ironment al Protec tion Agen cy (US-E PA) is the federal agency respon sible for regul ating the level of contamina nts in ambient a ir (Section 9.2.2.1), drinking water (Secti on 9.2.2.2), and soil (Section 9.2.2.3) while the U.S Food and Drug Adm inistration (US-F DA) is the federal agency respon sible for regul ating the level of contam inants in food (Section 9.2.2.4)
Trang 79.2.2.1 Air
The Clean Air Act (CAA), amended in 1970 and in 1990 (US-EPA 1990), is the federal law under which the US-EPA sets limits for air pollutants anywhere in the United States This ensures uniform basic health and environmental protection across the country The law allows individual states to have stronger pollution controls, but states are not allowed to have weaker pollution controls than those set for the whole country The states do much of the work to carry out the Act (US-EPA 2007a)
States have to develop state implementation plans (SIPs) that explain how each state will do its job under the Clean Air Act A state implementation plan is a collection of the regulations a state will use to clean up polluted areas The states must involve the public, through hearings and opportunities to comment, in the development of each state implementation plan
US-EPA must approve each SIP, and if a SIP is not acceptable, US-EPA can take over enforcing the Clean Air Act in that state
The U.S government, through US-EPA, assists the states by providing scientific research, expert studies, engineering designs, and money to support clean air programs
US-EPA refers to chemicals that cause serious health and environmental hazards as hazardous air pollutants (HAPs) or air toxics The 1970 Clean Air Act gave US-EPA authority to list air toxics for regulation and then to regulate the chemicals The agency listed and regulated seven chemicals through 1990 The 1990 Act includes a list of 189 hazardous air pollutants selected by Congress on the basis of potential health and=or environmental hazard; US-EPA must regulate these listed air toxics The 1990 Act allows US-EPA to add new chemicals to the list as necessary
US-EPA develops regulations, MACT (Maximum Achievable Control Technology) standards, requiring sources to meet specific emission limits that are based on emission levels already being achieved by many similar sources in the country Then US-EPA applies a risk-based approach to assess how these technology-based emission limits are reducing health and environmental risks Based on this assessment, US-EPA may implement additional standards to address any significant remaining, or residual, health or environmental risks
US-EPA is developing an air toxics risk assessment (ATRA) reference library for conducting air toxics analyses at the facility and community-scale This library provides information on the fundamental principles of risk-based assessment for air toxics and how to apply those principles
in different settings as well as strategies for reducing risk at the local level
A Technical Resource Manual is available, which gives comprehensive guidance on the risk assessment process (US-EPA 2004)
9.2.2.2 Drinking Water
The Safe Drinking Water Act (SDWA) is the main federal law that ensures the quality of the drinking water (US-EPA 2007b)
The SDWA was originally passed by Congress in 1974 to protect public health by regulating the nation’s public drinking-water supply The law was amended in 1986 and 1996 and requires many actions to protect drinking water and its sources: rivers, lakes, reservoirs, springs, and groundwater wells SDWA does not regulate private wells, which serve fewer than 25 individuals SDWA authorizes the US-EPA to set national health-based standards for drinking water to protect against both naturally occurring and man-made contaminants that may be found in drinking water US-EPA, States, and water systems then work together to make sure that these standards are met US-EPA sets national standards for tap water, which help ensure consistent quality in the water supply US-EPA prioritizes contaminants for potential regulation based on risk and how often they occur in water supplies Certain water systems are monitored for the presence of contaminants for which no national standards currently exist and collect information on their occurrence US-EPA sets a health goal based on risk, including risks to the most sensitive people, e.g., infants, children, pregnant women, the elderly, and the immuno-compromised US-EPA then sets a legal limit for the
Trang 8contaminant in drinking water or a required Treatment Technique (TT) This limit or TT is set to be
as close to the health goal as feasible US-EPA also performs a cost–benefit analysis and obtains input from interested parties when setting standards
US-EPA uses the following steps to set enforceable, health-based drinking-water standards:
. Determine whether a contaminant should be regulated based on peer-reviewed science,
including data on: how often the contaminant occurs in the environment; how humans are exposed to it; and the health effects of exposure (particularly to vulnerable subpopula-tions)
. Set a Maximum Contaminant Level Goal (MCLG) (the level of a contaminant in drinking
water below which there is no known or expected health risk MCLGs allow for a margin
of safety) These goals take into account the risks of exposure for certain sensitive populations, such as infants, the elderly, and persons with compromised immune systems These goals are not enforceable levels because they do not take available technology into consideration, and therefore are sometimes set at levels which public water systems cannot meet
. Propose an enforceable standard in the form of a Maximum Contaminant Level (MCL)
(the maximum amount of a contaminant allowed in water delivered to a user of any public water system) or a treatment technique (TT) (required procedure or level of technological performance set when there is no reliable method to measure a contaminant at very low levels) MCLs are set as close to MCLGs as feasible, considering available technology and cost Examples of rules requiring TTs are the Surface Water Treatment Rule (requires disinfection andfiltration) and the Lead and Copper Rule (requires optimized corrosion control) Water samples that contain lead or copper exceeding the action level trigger additional treatment or other requirements that a water system must follow Required testing (monitoring) schedules are part of the enforceable standard After determining a proposed MCL or TT that is as close to the MCLG as possible based on affordable technology, US-EPA must complete an economic analysis to determine whether the benefits of that standard justify the costs If not, US-EPA may adjust the MCL for a particular class or group of systems to a level that maximizes health risk reduction benefits
at a cost that is justified by the benefits US-EPA may not adjust the MCL if the benefits justify the costs to large systems and small systems that are unlikely to receive variances
. Set an enforceable MCL or TT After considering comments on the proposed standard and
other relevant information, US-EPA makesfinal an enforceable MCL or TT, including required testing and reporting schedules States are authorized to grant variances from standards for systems serving up to 3,300 people if the systems cannot afford to comply with a rule (through treatment, an alternative source of water, or other restructuring) and the systems install US-EPA approved variance technology States can grant variances to systems serving 3,301–10,000 people with US-EPA approval SDWA does not allow small systems to have variances for microbial contaminants Under certain circumstances exemptions from standards may be granted to allow extra time to seek other compliance options orfinancial assistance After the exemption period expires, the public water system must be in compliance The terms of variances and exemptions must ensure no unreason-able risk to public health
9.2.2.2.1 The Contaminant Candidate List
The 1996 Amendments to SDWA require that every 5 years US-EPA establish a list of contamin-ants which are known or anticipated to occur in public water systems and may require future regulations under SDWA The list is developed with significant input from the scientific community and other interested parties After establishing this contaminant candidate list, US-EPA identifies contaminants, which are priorities for additional research and data gathering US-EPA uses this
Trang 9information to determine whether or not a regulation is appropriate and this process is repeated for each list, every 5 years
In order to support this decision making, US-EPA has also established a National Contaminant Occurrence Database (NCOD), which stores data on the occurrence of both regulated and unregu-lated contaminants US-EPA is also required to list and develop regulations for monitoring certain unregulated contaminants This monitoring data will provide the basis for identifying contaminants that may be placed on future Contaminant Candidate Lists and support the US-EPA Administrator’s decisions to regulate contaminants in the future
9.2.2.3 Soil
The U.S National Environmental Policy Act of 1969 required careful analysis of the consequences
of any federally funded project The Resource Conservation and Recovery Act (RCRA) of 1976 established guidelines for handling, transport, and hauling of hazardous materials, such as required
in cleanup of soil contaminants The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980 established, for thefirst time, strict rules on legal liability for soil contamination CERCLA stimulated identification and cleanup of thousands of contaminated land sites, and consequently raised awareness of property buyers and sellers to make soil contamination a focal issue of land use and management practices (US-EPA 2007c)
9.2.2.3.1 The Comprehensive Environmental Response, Compensation, and Liability Act The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), com-monly known as Superfund, was enacted by the U.S Congress on 11 December 1980 CERCLA created a tax on the chemical and petroleum industries and provided broad Federal authority to respond directly to releases or threatened releases of hazardous substances that may endanger public health or the environment Over 5 years, $1.6 billion was collected and the tax went to a trust fund for cleaning up abandoned or uncontrolled hazardous waste sites (US-EPA 2007c)
CERCLA established prohibitions and requirements concerning closed and abandoned hazard-ous waste sites; provided for liability of persons responsible for releases of hazardhazard-ous waste at these sites; and established a trust fund to provide for cleanup when no responsible party could be identified
CERCLA authorizes two kinds of response actions: Short-term Removals, where actions may be taken to address releases or threatened releases requiring prompt response; and Long-term Remedial Response Actions, that permanently and significantly reduce the dangers associated with releases or threats of releases of hazardous substances that are serious, but not immediately life threatening These actions can be conducted only at sites listed on US-EPA’s National Priorities List (NPL) CERCLA also enabled the revision of the U.S National Contingency Plan (NCP) The NCP provides the guidelines and procedures needed to respond to releases and threatened releases of hazardous substances, pollutants, or contaminants The NCP also established the NPL
CERCLA was amended by the Superfund Amendments and Reauthorization Act (SARA) on
17 October 1986
9.2.2.3.2 The Superfund Program
The goal of the Superfund program is to clean up uncontrolled hazardous waste sites that pose unacceptable risks to human health and environment in a manner that restores these sites to uses appropriate for nearby communities As already mentioned, the program was authorized under the CERCLA of 1980 (US-EPA 2007c)
The Soil Screening Guidance, Technical Background Document (US-EPA 1996a) provides the technical background for the development of methodologies described in the Soil Screening Guidance: User’s Guide (US-EPA 1996b), along with additional information useful for soil screening Together, these documents define the framework and methodology to develop soil screening levels (SSLs) for chemicals commonly found at Superfund sites
Trang 10SSLs are risk -based concent rations deriv ed from standardiz ed equati ons combinin g exposur e infor mation assum ptions with US-EP A toxi city data Fo r the ingestio n, derm al, and inhal ation pathwa ys, toxicit y c riteria are used to de fi ne an accept able level of contamina tion in soil, based
on a o ne-in-a-m illion (10 6) indi vidual excess cancer risk for carcinogens and a Hazard Quot ient (HQ) of 1 for noncarc inogen s The hazard quotient is de fine d as the ratio of an exposur e esti mate over the Ref erence Dos e o r Con centratio n (Secti on 5.1), i.e., HQ ¼ Exp osure=(RfD or RfC) 9.2.2 4 Foo d
The US-FDA is the federal agenc y respon sible for regul ating the level of contam inants in food (US- FDA 2007) The US-FDA establishe s ‘‘ action level s ’’ for poiso nous or deleterio us substances
to control levels of contam inants in human food and anim al feed
Act ion level s and tolerances are estab lished based on the unavoi dabilit y of the p oisonous or delet erious subst ances and do not represent perm issible levels of contam ination where it is avoid-able The blendi ng of a food or feed containing a substance in excess of an action level or tolerance with anothe r food or feed in order to lower the concent ration of a con taminant is not perm itted, and the final product resultin g from blending is unlawful , regard less of the level of the contam inant Act ion level s and tole rances represent limits a t or above which the US-FDA will take legal acti on to remo ve product s from the mark et Whe re no established a ction level or tole rance exists, the US-FD A may take legal action against the product at the minimal detectable level of the contam inant
The action level s are establis hed and revise d according to crit eria speci fied in Title 21, Code of Federal Regulat ions, Parts 109 and 509 and are revoked when a regulatio n establish ing a tolerance for the same subst ance and use becom es effective
Wit h respec t to veter inary medicines , the US-FDA establis hes tolerances to include a safety facto r to assure that the drug will have no harm ful effects on consum ers of the food product The US-FD A first deter mines the level at which the drug doe s not produce any meas urable effect in labor atory animals From this, the US-FDA determin es an accept able daily intake (ADI), and the drug tolerance and withdr awal times are then deter mined so that the con centratio ns of drug residues
in edible tissues are below the ADI Depe nding on the drug, ‘‘safet y facto rs ’’ of betwee n 100-fo ld to 2000-f old a re incl uded in the calcul ations used to set the tolerances
9.2.3 1 Air
Since the early 1970s, the Eur opean Union (EU) has been working to improve air quali ty by contr olling emissi ons of harmful substances into the atmospher e, improvi ng fuel quality, and
by integrati ng en vironment al prote ction requi rements into the trans port and energy secto rs Thr ough EU legi slation, major air poll utants have been regul ated For examp le, throu gh an EU Directi ve (EC 1999), the EU has estab lished limit values for concent rations of sulfur dioxi de, nitrogen dioxide and nitrogen oxides, particulate matter and lead, as well as alert thresholds for concentrations of sulfur dioxide and nitrogen oxide, in ambient air Member States must take the measures necessary to ensure that concentrations of the pollutants in ambient air do not exceed the limit values
The EU’s Sixth Environment Action Programme (EAP), ‘‘Environment 2010: Our future, Our choice,’’ includes Environment and Health as one of the four main target areas requiring greater effort Air pollution is one of the issues highlighted in this area The Sixth EAP aims to achieve levels of air quality that do not result in unacceptable impacts on, and risks to, human health and the environment
The EU is acting at many levels to reduce exposure to air pollution: through EC legislation, through work at international level to reduce cross-border pollution, through cooperation with