Pesticides, lead and solvents: pregnancy outcome and fertility

Markku Sallmén

Finnish Institute of Occupational Health

Pesticides

The most extensively used group of toxic chemicals

ca. 600 different active ingradients about 50,000 various formulations simultaneous exposure to different

chemicals typical pesticide formulations may contain

solvents

Pesticide exposure in farming

Most of the exposure occurs via the skin Some pesticides degrade on the leaves into

more toxic compounds with even stronger penetration capacity

Inhalation during applications Mixing, formulation, spraying, handling of

treated plants, cleaning of equipment and clothes, storage

Pesticides

Comparison between studies difficult Different pesticides are used for different

purposes and in different areas Exposure levels vary considerably; the

highest exposures occur in developing countries in poorly controlled circumstances

What is the affected gender?

Pesticides shown adverse effects on spermatogenesis

DBCP 2,4-D (2,4-dichlorophenoxy acetic acid) ethylene dibromide chlordecone carbaryl

Pesticides and semen quality

Study Outcome Larsen et al 1998 (longitudinal study) – multiple outcomes Larsen et al 1999 (organic/traditional) – multiple outcomes Padungtod et al 1999 (factory workers) + aneuploidy Tielemans et al 1999 (inf clinic clients) (+) combined quality Juhler et al 1999 (dietary pesticides)– dead spermat. Oliva et al 2001 (infertility clinic clients) + multiple outcomes Abell et al 2000 (greenhouse workers) + concent./morphol Wong et al 2003 (population based) + oligozoospermia Dalvie et al 2003 (DDT, malaria control) – multiple outcomes Swan et al 2003 (population based) + summary of many Sanchez-Pena et al 2004 (organophos.) + sperm chromatin+ = reduced semen quality, (+) suggestive association– = no association

Pesticides and male fecundability

Study Association de Cock et al 1994 + Larsen et al 1998 - Thonneau et al 1999 - Curtis et al 1999 (+), gender? Petrelli et al 2001 + Sallmén et al 2003 (+)+ = reduced fecundability, (+) suggestive association

Male pesticide exposure and couples undergoing IVF treatment (Tielemans et

al 1999, 2000)

Reduced fertilization capacity– OR for confirmed exposure 0.38 (0.19-0.78)

– OR for potential exposure 0.54 (0.29-0.99) Improved implantation rate

– OR for high/moderate exposure 3.31 (1.25-8.80)– OR for high(strict) exposure 1.57 (0.33-7.44)

Summary effect?

Male pesticide exposure and spontaneous abortion

Savitz et al 1994, reviewed 14 studies:

elevated RR in >1 study: YES RR > 1.5 YES Evidence from high

quality studies: NOThereafter mainly US studies have shown

associations with spontaneous abortion

Male pesticide exposure and congenital malformations

García 1998, a review on occupational exposure and congenital malformations:17 studies 4 studies showed an association

Conclusion: Inadequate evidence for either establishing a relationship between pesticides exposure in humans and birth defects or for rejecting it.

Male pesticide exposure and congenital malformations

Pesticide applicators in the Red River Valley of Minnesota (Garry et al, 1996, 2002)1996 a register-based study

- excess in birth defects

- seasonal pattern

2002 a cross-sectional interview study- rate of birth defects 7.6% (spring) vs. 3.7% other season

- herbicides: risk of birth defects

- fungisides: determination of sex of the child

Salazar-Garcia et al 2004 (DDT); OR 3.4 (1.2-9.5)

Conclusion: Male pesticide exposure

High exposure associated with reduced semen quality

Inconsistent findings on fecundability Small number of TTP studies The findings of the new studies seem to have

added the evidence that male (or parental) exposure to pesticides is associated with adverse pregnancy outcome

Pesticides and female fertility

Study Association

Fuortes et al 1997 + Greenlee et al 2003 + Curtis et al 1999 + (6 of 13 pesticides)

Abell et al 2000 +

+ = reduced fertility

Summary:Female pesticide exposure and fecundability

There is evidence that female high exposure to pesticides is associated with reduced fecundability

This conclusion is based on small number of studies, however

Female pesticide exposure and adverse pregnancy outcome

Nurminen 1995, and Garcia 1998 reviews: Conclusion: the epidemiologic evidence is

inconclusive as regards the risk of adverse pregnancy outcome

Conclusion: Inadequate evidence for either establishing a relationship between pesticides exposure in humans and birth defects or for rejecting it.

Female exposure to specific pesticides and spontaneous abortion

Exposure/Study Association (OR)Hexachlorobenzene (serum, ng/ml):

Jarrell et al 1998 <1 1.6p=0.113

>14.1 p=0.02

DDT; serum p,p'-DDE measured:

Korrick et al 2001 (each ng/g) 1.13 1.02-1.26

Longnecker et al 2003 (per 60 µg/L)

1.4 1.1-1.6

Pesticides and congenital malformations or foetal death

Female: Exposure assessment Pastore et al 1997 (popul based case-control) + female occup exp Bell et al 2001 (popul based case-control) + residence/application Longnecker et al 2002 (popul based case-c) (+) p,p'-DDE Ribas-Fito et al 2003 (birth cohort, neurodev.) + p,p'-DDE Medina-Carrilo et al 2002 (popul based case-c) + female occup exp Bell et al 2001 (fetal death, popul case-cohort) (+) residence/application Male: Garcia et al 1998 (case-referent) + interview, experts Garry et al 2002 (cross-sectional, popul based) + spring vs. other Regidor et al 2004 (population based) + season Either gender: Kristensen et al 1997(cohort ) + agricultural census Schreinemachers 2003 (population b.) + ecologic

+ = increased risk, (+) suggestive association

Pesticides conclusion: females

Several studies with varying outcomes, pesticides, level of exposure, affected gender, and quality of the study

High exposure seems to be associated with increased risk

Exposure should be restricted through efficient protection

Should pregnant be transferred?

Lead: Pregnancy outcome and fertility

Simultaneous exposure to several metals

Studies around Rönnskär copper smelter

excess of spontaneous abortion, and stillbirths in pregnancies of wives of men exposed to lead, copper, zinc, gold, silver, cadmium, mercury, arsenic, and sulfur dioxide

carry-home exposure to the wives remains a possible alternative explanation

Population-based studies

Rachootin and Olsen 1983

case couples examined or treated for a problem of infertility at Odense University Hospital

questionnaire information on job and exposure

female exposure to lead, mercury, and cadmium were associated with infertility

Maternal lead exposure and spontaneous abortion

B-Pb µmol/L OR 95% CI

A retrospective study among biologically monitored workers:

Taskinen 1988 0.5-3.1 0.8 0.5-1.4Measured within a year of pregnancy:

>1.4 1.9 0.4-9.4

A prospective study (B-Pb measured at gestational age 4-12 w):

Borja-Aburto 0.24-0.48 2.3 --et al. 1999 0.49-0.72 5.4 --

> 0.72 12.2 --

Maternal lead exposure and fecundability

Sallmén et al 1995 (study among women biologically monitored for exposure to lead)

Blood lead FDR 95% CI

not exposed 1.00 reference

<0.5 µmol/l 0.93 0.56-1.57

0.5-0.9 µmol/l 0.84 0.45-1.45

1.0-2.4 µmol/l 0.80 0.42-1.54

Eight most heavily exposed subjects:

1.4-2.4 µmol/l 0.53 0.19-1.52

Maternal lead exposure and cognitive development; prospective studies

Study Mean Blood Lead Effect

Boston 7.37 µg/dl +

Cincinnati 4.6 --->14.1 +

Cleveland5.8 ---> 6.5 -

Port Pirie 14.4->21.2->17.6 +

Sydney 9.1->8.1->12.5 -

Yugoslavia 14.4--->24.3 (+/-)

1 µmol/L = 20.7 µg/dL

Lead and semen quality

Apostoli et al 1997 (a review): Exposure to lead at blood lead 1.9 µmol/L (40

µg/dL) is hazardous for male reproductive function reduced sperm count, volume, and density changed sperm motility and morphology a modest effect on endocrine profile is possible

Viskum et al 1999: The effect is, at least partially, reversible

Studies on birth rates and male exposure to lead

Study PbB level Effect

Selevan et al. 1984 1.2 µmol/l + Coste et al. 1991 1.9 µmol/l - Gennart et al. 1992 2.2 µmol/l + Lin et al. 1996

–duration of exp. >5 years, 2.4 µmol/l + Bonde and Kolstad 1997 1.8 µmol/l -

+ reduced fertility, - no effect

Relative risk (RR) of infertility and male exposure to lead; Sallmén et al 2000

Estimated PbB RR 95% C.I. µmol/L

0.5-0.9 1.27 1.08-1.51

1.0-1.4 1.35 1.12-1.63

1.5-1.9 1.37 1.08-1.72

2.0-2.4 1.50 1.08-2.02

> 2.5 1.90 1.30-2.59

Fecundability Ratio by Male Lead Exposure

0

0,5

1

reference <1.0 1.0-1.4 1.5-1.9 >1.9

Blood lead (µmol/L)

Fec

un

dab

ility

Rat

io

Sallmen et al

J off e et al

shiau et al

Male lead exposure and spontaneous abortion

Study PbB µmol/L OR 95% CI Selevan 1984 1.2 - 1.9 1.5 0.8-3.0

2.0 - 2.9 1.1 0.6-1.9> 3.0 0.9 0.3-2.3

Al-Hakkak 1986 1.8 - 4.6 3.0 p<.01Lindbohm 1991 1.0 - 1.4 1.0 0.6-1.7

1.5 - 1.8 1.3 0.5-3.4> 1.9 1.6 0.6-4.0

Alexander 1996 1.2 - 1.8 1.0 0.6-1.7> 1.9 0.7 0.4-1.5

Male lead exposure and congenital malformations or perinatal death

Study PbB µmol/L OR 95% CI M:Sallmén 1992 > 1.0 2.4 0.9-6.5P:Kristensen 1993 exposed 2.4 1.2-4.9P/M:Alexander 1996 1.2 - 1.8 2.9 0.6-13

> 1.9 2.5 0.5-11

M=malformation studyP=perinatal death study

Solvents: pregnancy outcome and fertility

From a presentation of:

Dr. Marja-Liisa LindbohmFinnish Institute of Occupational Health

Organic solvents

important occupational reproductive hazards: widely used in various fields of industry volatile liquids absorbed via inhalation and through the

skin most solvents traverse the placenta diverse group of compounds

Reproductive effects of solvents

in several human studies exposure related to reduced fertility spontaneous abortions birth defects low birth weight

in some studies exposure related also to menstrual disorders and change in hormone levels pregnancy-induced hypertension neurobehavioral performance reduced semen quality childhood cancer

Maternal exposure to solvents in some occupations and spontaneous abortion

Population

Relative risk (OR)

95% CI

Laboratory workers 1.3 0.9 - 1.9

Laboratory workers: low exposure 1.0 0.6 - 1.7

high exposure 2.3 1.1 - 4.3

Painters (questionnaire data) 2.9 1.0 - 8.8

Painters (register data) 1.4 0.4 - 2.5

Workers monitored for solvents 2.2 1.2 - 4.1

Shoe workers: low exposure 1.6 0.6 - 4.1

high exposure 3.8 1.2 - 11.9

Cumulative percentage of pregnancies by maternal exposure to solvents (Sallmén et al 1995)

0

20

40

60

80

100

1 2 3- 5- 7- 13-24Menstrual cycle

pre

gn

ant,

%

UnexposedLowHigh

Industries and individual solvents related to reduced fertility or adverse pregnancy outcome

Dry cleaning: tetrachloroethylene Semiconductor industry: ethylene glycol

ethers Shoe and leather industry: aliphatic

hydrocarbons, toluene, hexane Laboratory work: toluene, xylene,

chloroform

Ethylene glycol ethers

used in paints, dyes, lacquers, waxes etc.Methoxyethanol embryotoxic and teratogenic in mice and

rats teratogenic effects seen at doses that do

not cause overt maternal toxicityEthoxyethanol induced skeletal defects in rats, multiple

defects in rabbits (inhalation exposure) in rats, impaired performance in behavioral

tests

Spontaneous abortion, fertility and maternal exposure to mixtures containing ethylene glycol ethers in semiconductor industry (Correa et al. 1996, Chen et al 2002)

Outcome Exposure RR/FR 95% CI

Spontaneous abortion: low 1.0 0.6 – 1.7

Correa et al medium 1.4 0.8 – 2.6high 2.8 1.4 – 5.6

Time-to-pregnancy:Correa et al medium 0.8 0.6 – 1.1

high 0.7 0.4 – 1.1Chen et al Exposed 0.59 0.37 –

0.94

Conclusions: Effects of solvent exposure on the reproductive health of women

High exposure to solvents increases the risk of spontaneous abortion and decreases fertility

The findings on birth defects less conclusive, but suggesting adverse effects

Particular solvents associated with adverse effects: ethylene glycol ethers, tetrachloroethylene, toluene

Exposure assessment and recommendation

Assessment of solvent exposure with industrial hygienic measurements or biological monitoring

In some countries the guidelines recommend that solvent exposure should not exceed 10% of the threshold limit value during pregnancy

Reproductive effects have been used as the basis for some TLVs

Exposure to solvents and semen quality or hormone levels

Solvents: reduced sperm quality and decreased implantation rate

Ethylene glycol ethers and 2-bromopropane: reduced sperm count

Styrene and acetone: sperm anomalies Toluene and solvents in general:

decrease of hormone levels

Solvent exposure and seminal characteristics in 225 men who had their first infertility consultation (Oliva et al 2001)

Seminal charateristic OR 95% CI

Seminal volume >3.8 ml 2.4 0.8 – 7.6

Sperm concentration <1x106/ml

2.7 0.9 – 8.3

Sperm output <3x106 2.5 0.8 – 7.9

Sperm motility <50% 3.1 1 – 9.5

Sperm morphology <30% 3.0 1.0 – 9.0

Cumulative percentage of pregnancies by paternal exposure to solvents (Sallmén et al. 1998)

0

20

40

60

80

100

1 2 3- 5- 7- 13-24Menstrual cycle

pre

gn

an

t, %

UnexposedLowHigh

Ethylene glycol ethers and male fertility

Study

FR 95% CI

Samuels et al. 1995

Time-to-pregnancy 1.03 0.70 - 1.51

Correa et al. 1996

Time-to-pregnancy

- Low exposure 0.8 0.6 - 1.1

- Medium exposure 0.9 0.6 - 1.2

Paternal exposure to solvents and spontaneous abortion

Exposure Odds ratio 95% CI

Workers monitored for solvents 2.7 1.3 - 5.6

Styrene (high) 0.7 0.4 - 5.1

Toluene (high) 2.3 1.1 - 4.7

Xylene (high) 1.6 0.8 - 3.2

Dry cleaners (tetrachloroethylene) 0.7 p=0.57

Benzene exposure (high) 1.2 0.7 - 2.1

Ethylene glycol ethers (high) 0.7 0.3 - 1.6

Paternal solvent exposure and pregnancy outcome

Inconsistent findings on the effects of exposure on low birth weight

An excess of birth defects in the children of male painters, but not in the children of other exposed workers

Some evidence for childhood leukemia or nervous system cancers, and paternal exposure to solvents

Evidence inconclusive, although suggestive associations noted

Conclusions: Effects of solvent exposure on the reproductive health of men

Solvent exposure related to reduced sperm quality

Ethylene glycol ethers harmful for male reproductive system

Carbon disulfide related to decreased libido and potency in men

No clear association between solvent exposure and decreased fertility

Male pesticide exposure and spontaneous abortion

Study Association (OR) Arbuckle et al 1999, Ontario Farm Family

Study, phenoxy herbicides<20 weeks of gestation 1.1 0.6-1.9<12 weeks of gestation 2.5 1.0-6.4husband not using protective 5.0 0.7-36.2equipment

Petrelli et al 2000 3.8 1.2-12.0

Crisostomo et al 2002 6.2 1.4-27.9 Salazar-Garcia et al 2004 (DDT)1.5 1.1-2.1

Male/female pesticide exposure and spontaneous abortion

Arbuckle et al 2001Ontario farm population

Timing of exposure / affected gender:

preconceptional early (<12 weeks) abortions(male exposure?)

postconceptional late (12-19 weeks) abortions(female exposure?)

Male pesticide exposure and spontaneous abortion Pesticide applicators in the Red River Valley

of Minnesota (Garry et al, 2002) Fungicides: 1.6-2 -fold increase in risk for

miscarriage/fetal loss Herbicides: increased risk in first-trimester

miscarriage The overall toxicity data suggest a male-

mediated event Also, women engaged in pesticide

application were at risk

Female pesticide exposure and spontaneous abortion

StudyAssociation

Bell et al 2001pesticides showed no strong association with fetal death(ORs from 0.9 to 1.4)

Exposed: lived in 1+ 8 adjacent sq miles fromthe application

Parental pesticide exposure and congenital malformations

Kristensen et al 1997; a study among Norwegian farmers

Exposure to pesticides associated with:spina bifidahydrocephalylimb reductioncryptorchidismhypospadias

Fecundability Density Ratio (FDR) of Pregnancies by Father’s Exposure to Lead; Sallmén et al 2000

Estimated PbB µmol/l N FDR 95% C.I.

0.5-0.9 203 0.92 0.73 - 1.16

1.0-1.4 79 0.89 0.66 - 1.20

1.5-1.8 21 0.58 0.33 - 0.96

> 1.9 23 0.83 0.50 - 1.32

> 1.5 (combined) 44 0.70 0.47 - 1.01

Reproductive effects of some solvents in animal tests

ethoxyethanol: teratogenic and spermatotoxic effects

methyl alcohol: teratogenic effects methyl ethyl ketone: decreased fetal

body weight n-hexane: testicular lesions xylene and white spirit (prenatal

exposure): learning and memory defects

Maternal exposure to solvents and pregnancy outcome: a meta-analysis(McMartin et al. 1998)

559 articles identified; around epid. studies 90

Spontaneous abortions five studies included (n=2899) summary OR=1.25 (95% CI 0.99 – 1.58)

Birth defects five studies included (n=7036) summary OR=1.64 (95% CI 1.16 – 2.30)

Reasons used for the exclusion of (several potentially important) studies criticized

Tetrachloroethylene

used as a dry cleaning agent and degreaser passes across the placenta animal studies:

no clear teratogenic effects signs of fetotoxicity observed in some studies a two-generation study found decrease in litter

size and postnatal survival at 300 ppm propably carcinogenic to humans (2A, IARC)

Maternal exposure to tetrachloroethylene in dry cleaning and spontaneous abortion

Study Odds ratio 95 % CI

Kyyrönen et al. 1989 3.4 1.0 - 11.2

Ahlborg et al. 1990 1.1 0.5 - 2.2

Olsen et al. 1990 2.9 1.0 - 8.4

Doyle et al. 1997 1.6 1.0 - 2.7

Toluene

used in paints, inks, coatings, adhesives, and in the leather, rubber and graphic industries

low birth weight, microcephaly and facial abnormalities in children of women abusing toluene by inhalation during pregnancy

reduced birth weight in prenatally exposed rat pups

effects on cognitive function reported in rats after prenatal exposure

Maternal exposure to toluene and spontaneous abortion or reduced fertility

Population Relative risk 95% CI

Spontaneous abortions OR

Pharmaceutical factory w.

1.9 0.6 – 6.4

Laboratory workers 4.7 1.4 – 15.9

Monitored workers 1.4 0.4 – 4.9

*Audio speaker factory w.

2.8 1.3 – 5.9

Reduced fertility (ttp) FDR

Monitored workers 0.71 0.40-1.26

*Printing industry workers

0.47 0.29-0.77

Maternal exposure to solvents and oral clefts

Study Odds ratio 95 % CI

Holmberg et al. 1982 14 exp. cases, 4 exp.

controls

p<0.05

Cordier et al. 1992 7.9 1.8 - 44.9

Laumon et al. 1996 1.6 1.0 - 2.5

Cordier et al. 1997 (glycol ethers)

1.9 1.0 - 3.5

Methodological issues in epidemiologic studies on solvents

response rates satisfactory in most studies confounding usually, but not always controlled for outcome data mainly from the medical records

data on exposure usually based on workers’ own reports - underreporting ?

in some studies exposure assessed by experts exposure to mixture of solvents common

small sample size in studies on birth defects and individual solvents

Reproductive endocrine effects in women with fuel/solvent exposure (Reutman et al 2002)

Outcome: urinary endocrine markers related to nonconceptive menstrual cycles (N=63)

Exposure assessment: levels of aliphatic and aromatic hydrocarbons (HCs) in exhaled breath

Result: preovulatory luteinizing hormone level significantly lower among women who had higher internal doses of aliphatic HCs

Conclusion: compounds in fuel and some solvents may act as reproductive endocrine disruptors

Genetic susceptibility to benzene and shortened gestation (Wang et al 2000)

Aim: examine whether the association between exposure and outcome is modified by two susceptibility genes CYP1A1 and GSTT1 responsible for detoxification of solvents (542 mothers)

Results: benzene exposure associated with a decrease in

mean gestational age when stratified by the maternal CYP1A1

genotype, the decrease was significantly greater for the AA group than for the AA/aa group

Provide evidence of gene-environment interaction

Carbon disulfide exposure and the prevalence of sexual complaints

Sexualcomplaint

Non-exposed

Lowexposure

Highexposure

p-value

Decreasedlibido

13.9% 13.6% 37.2% .005

Impotence 3.8% 9.1% 20.0% .02

Vanhoorne et al. 1994

Solvent exposure and count of motile sperm (Cherry et al 2001)

A case-referent study of 656 infertility patients

Aim: to examine whether cases with low motile sperm count (<12x106ml) were more likely than referents to have had exposure to solvents

Exposure assessment: job exposure matrix of previous studies on solvent exposure

Results: OR 2.1 (95% CI 1.2-3.4) for moderate exposure OR 3.8 (95% CI 1.4-10.6) for high exposure